Histology Review & Colored Atlas part 2 [2]

Table of contents :
Cover
......Page 1
Contents
......Page 7
The Tongue......Page 9
Lingual Papillae......Page 10
Taste Buds
......Page 11
Parotid......Page 12
Secretory Serous Acini......Page 13
Submandibular......Page 14
Parenchyma......Page 15
Sublingual......Page 16
The Oesophagus......Page 17
The Stomach......Page 18
Fundic Gastric Glands......Page 19
Pyloric Gastric Glands......Page 21
Intestinal Villi......Page 23
Intestinal Crypts Of Lieberkuhn
......Page 25
Brunner's Glands......Page 26
Large Intestine......Page 27
Vermiform Appendix......Page 28
Recto-Anal Junction......Page 29
Parenchyma......Page 30
Liver Cells Or Hepatocytes......Page 32
Duct Systems For Biliary Passages......Page 33
Pancreatic Acini......Page 34
Islets Of Langer hans
......Page 35
Differences Between parotid And pancreas......Page 38
C. T. Stroma......Page 39
Suprarenal Cortex......Page 40
Suprarenal Medulla......Page 41
The Pituitary Gland......Page 42
Mammotroph......Page 43
Corticotroph......Page 44
Chromophobe Cells......Page 45
Pars Nervosa......Page 46
Hypothalamus......Page 47
The Thyroid Gland......Page 48
parafollicular C- Cells......Page 49
The Parathyroid Gland......Page 50
APUD Cells......Page 51
Renal Malpighian Corpuscles......Page 52
Podocytes
......Page 53
Mesangial Cells
......Page 54
Juxta Glomerular Complex (Apparatus)......Page 55
Proximal Convoluted Tubule
......Page 56
Distal Convoluted Tubule
......Page 57
Collecting Tubules
......Page 58
Blood Supply Of Nephron......Page 59
Urinary Bladder
......Page 60
Seminiferous Tubules......Page 61
Spermatogenic Cells and Spermatogenesis......Page 62
Sertoli Cells......Page 64
Spermiogenesis......Page 65
Interstitial Cells Of Leydig......Page 66
Male Genital Ducts......Page 67
Prostate......Page 69
Penis......Page 70
Male urethra......Page 71
Ovarian Follicles......Page 73
Fate Of Mature Graafian Follicle......Page 76
Corpus Luteum......Page 77
Uterine Fallopian Tubes or Oviducts......Page 78
Uterus......Page 79
Menstrual uterine Cycle......Page 80
Placenta......Page 81
Vagina......Page 83
Mammary Glands......Page 84
Cornea......Page 86
Sclera......Page 87
Iris......Page 88
Choroid......Page 89
Lens......Page 90
Retina......Page 91
Eye Lids
......Page 95
Middle Ear......Page 96
Organ Of Corti......Page 97
Vestibular Apparatus......Page 99
CerebroSpinal Fluid (C.S.F.)......Page 101
Grey Matter Of The Spinal Cord......Page 102
White Matter Of The Spinal Cord......Page 103
Long Ascending Sensory Tracts......Page 104
Cortico Spinal Tracts......Page 106
Extrapyramidal Tracts......Page 107
Vagus......Page 110
Cochlear or Auditory Pathway......Page 111
Vestibular Nerve......Page 112
Taste Pathway......Page 113
Trigeminal......Page 114
Occulomotor......Page 116
Red Nucleus......Page 117
Medial Longitudinal Bundle (MLB)......Page 118
Reticular Formation......Page 119
Cerebellum......Page 120
Cerebrum......Page 122
Slides Collection
......Page 124

Citation preview

.....

Review And Coloured Atlas Of

HISTOLOGY For M:edical, Dent:ist:ry; Pharmacy Veterinary And Post:graduat:e Part: II By Professor

Zakaria Abd-Elhamid Head Of Histology Department Faculty Of Medicine Cairo University

All Rights Reserved To The Author

Preface The purpose of this book is to provide medical students with a concised but fully illustrated account of normal human histology. It is hoped that this coloured illustrated book will be of great value to supply medical students with photomicrographs from their actual these place may laboratory slides. They photomicro graphs beside their microscopes while viewing sections of normal histological or abnormal labelled

pathological materials. This book is not intended to replace comprehensive text books of histology but rather to complement them and to add more details about the structure and functions of organs. The content and design of this book have been chosen to make it easy to use both as a short text and as a laboratory guide. It is hoped that this illustrated text will be of great value to fulfill the requirement s of medical, dentistry, pharmacy and veterinary students. It also should have a wide appeal for the post graduate medical members and Primary Fellowship examinations. In presenting this book, I should like to express my appreciation for the help and encouragem ent that I have received from my wife.

Prof. Zakaria Abd-ELHamid

Contents Page The Digestive System .... ·............................................................ The Lip .................................................................................:··

1

The Tongue ........................................................................ :... The Salivary Glands...............................................................

2

The Oesophagus...................................................................... The Stomach............................................................................ The Intestine .............................................. ;............................

9

1 4 l0 15

The Liver........................................................ _,....................... The pancreas........................................................................... The Endocrine Glands................................................................

22

The Suprarenal Gland............................................................ The Pituitary Gland .................................... ;............. ·..............

31

The Thyroid Gland................................................................. The Parathyroid Gland........................................................... The ~Urinary System...................................................................

40

The Male Genital System........................................................... The Female Genital System....................................................... The Eye...................................................................................... The Ear.......................................................................................

53

The Central Nervous System .............................. :......................

93

26 31 34 42 44 65 . 78 88

Lip

.

Filiform And Fungiform Papillae

\

\

Circumvallate Papilla

The Digestive System The Components Of The Digestive System Are:1- Oral Cavity : Lip, Tongue, Palate and Cheeks 2- Digestive Tract: Oesophagus, Stomach, Intestine and Anal Canal . 3- Digestive Glands : Salivary glands, Liver and Pancreas. The Oral Cavity is lined with non-keratinized stratified squamous epithelium. Connective tissue and minor salivary glands are present under the epithelium.

The Lips The upper and lower lips are formed of skeletal voluntary muscles called orbicularis oris. - The Outer Surface of each lip is covered with thin hairy skin. It is dry and opaque. It is covered by keratinized stratified squamous epithelium. Hair follicles, sebaceous and sweat glands are present in the C.T corium under the epithelium. - The Inner Surface of each lip is covered with red translucent wet thick mucous membrane. It is covered with non-keratinized stratified squamous epithelium. - Labial muco-serous glands are present under the mucous membrane. The Red Margin of each lip is called Vermillion and is covered with red wet partially keratinized stratified squamous epithelium

The Tongue - It is a muscular organ formed of voluntary skeletal muscles covered by mucous membrane. The muscles are arranged in 3 directions, longitudinal, transverse and vertical.

-1-

- The Ventral Surface of the tongue is covered by loosely attached mucous membrane formed or non-keratinized stratified sq uam ous epithelium.

- The Dorsal Surface of the tongue is covered by firmly adherent mucous membrane

formed

of partially

keratinized

strat ified

squamous epithelium. -The anterior 2/3 of the d01·sal surface of the tongue contains filiform and fungiform lingual papillae

Different Types Of Lingual Papillae 1- Filiform Papillae are conical in shape formed of C.T. covered with keratinized stratified squamous epithelium with no taste buds.

2- Fungiform Papillae: They have narrow bases and broad tops. They are formed

of C.T.

covered

with

non-keratinized

stratified

squamous epithelium with few taste buds.

3- Circumvallate Papillae: They are from 8 to 12 in number, present in a V -shaped groove on the dorsal surface of the tongue. Each papilla is surrounded by a deep groove and is formed of C.T. covered with partially keratinized stratified squamous epithelium rich in taste buds.

Von Ebner Glands. They are serous sa livary glands present in the deep surface of the circumvallate papillae. They secrete saliva which facilitate taste sensation.

4- Foliate Papillae are present mainly in tongue of rabbits. They are poorly developed in tongue of man . Each Papilla is formed of few ridges of C.T. ' covered with keratinized stratified !:Ai~~~~ -'"J"'_Jo...

f'..,;

squamous epithelium rich in taste buas.

-2-

\,

~,~.-~ .-~ ....

They are neuro-epithelial organs present on the tongue, soft palate , epiglottis and pharynx

Each taste bud is formed of the following cells:1- Receptor taste cells or gustatory cells. They .1re columnar cells with Pale nuclei. They arc provided with microvilli which extend to the taste pores. They are SLirrouncled by sensory nerves. There arc 4 types of taste cells each one respond to sweet, salt, bitter and sour.

2- Supporting cells: They are columnar cells with clark nuclei. They have long microvilli which project into the taste pores. They secrete special secretion in the taste pores to facilitate the process of taste sensation. -3-

A Taste Bud

3- Basal Cells: They are low columnar cells present at the base of the taste bud. They act as stem cells for renewal of other cells. The Hard Palate: It is formed Qf bone and is covered with keratinized stratified squamous epithelium. The Soft Palate: It is formed of skeletal muscles covered with non keratinized stratified squamous epithelium on its inferior surface and with pseudo stratified columnar ciliated epithelium on its superior surface. The Nasopharynx: It is lined with pseudo-stratified columnar ciliated epithelium with goblet cells. The Oropharynx: It is lined with non-keratinized stratified squamous. The Laryngopharynx: It is lined with non-keratinized stratified squamous epithelium.

The Salivary Glands - They secrete saliva which moistens the mouth, washes the oral cavity from food remnants, helps in taste sensation and in swallowing of food. It digests starch and protects the mouth against organisms. - Accessory Salivary Glands are present in the lip, tongue, cheek and palate. -Major Salivary Glands are parotid, submandibular and sublingual.

The Parotid Gland - There are 2 parotid glands present in front of both ears, they secrete saliva and parotin hormone. (Zakaria, 1982) -Each gland is formed of C.T. stroma whi~h support the gland and parenchyma which secrete the parotid secretion. 1- The C. T. Stroma of parotid gland is formed of: a-Capsule: It is formed of C.T.. cells and C.T. fibres and is covered with fascia and skin.

-4-

b- Trabeculae: They are the C.T. septa which divide the gland into lobes and lobules. They are formed of C.T. cells and fibers. c- Reticular C.T. Network: It is present in the background of the lobes and lobules . Jt is formed of reticular cells and fibers. 2- The Parenchyma of parotid gland is formed of : a- Secretory Serous Acini . b- Secretory Ducts. c-Excretory Ducts. a-The Secretory Serous Acini Of Parotid Gland

- Each acinus is formed of a group of cuboidal secrotery cells surrounding a narrow lumen. -The acini are enclosed from outside by basement membranes and by myoepithelial cells (Basket Cells). - Their cytoplasm is rich in basophilic granules, mitochondria, rough endoplasmic reticulum ribosomes and apical zymogen granules. - Their nuclei are rounded and central in position . - Many secretory.canaliculi are present between their lining cells. - Serous acini secrete serous watery saliva rich in enzymes. Intercalated Duct

... . , :~

••

-

~

__

0

Parotid Salivary Gland -5-

b- The Secretory Ducts Of Parotid Gland 1- The Intercalated Ducts: - They are small ducts which are continuous with the serous acini . --- They are lined with cubical cells which secrete Parotin Hormones, Insulin Hormone and Growth Factors (Zakaria 1998). Some of these cells act as stem cells

2- The Secretory Intralobular Striated Ducts - They are continuous with the intercalated ducts. - They are lined with simple cuboidal cells. - Each cell has basal striations due to presence of many mitochondria and due to basal infolding of their cell membranes . - They have acidophilic cytoplasm and apiCal nuclei -These ducts secrete bicarbonate rendering the saliva alkaline in reaction.

C- The Excretory Ducts Of Parotid Gland. 1- The Interlobular Ducts: They are present in the connective tissue septa between the lobules of parotid gland. They are lined with high simple columnar cells. 2- The interlobar Ducts: They are present between the lobes of parotid gland. They are lined with pseudostratified columnar epithelium. 3- The Main parotid Duct: It is lined with stratified columnar at its beginning part and then with stratified squamous at its opening in the mouth cavity. .

The Submandibular Salivary Glands - They are compound tubulo~acinar glands present close to the inner aspect of the mandible. - They are mixed muco-serous glands formed of serous, ~ucous and mucoserous acm1 . - Each gland is formed of a connective tissue stroma and a

parenchyma of secretory cells. -6-

A- The C.T. Stroma Of Subma ndibula r Gland is Formed Of: 1- Thick Capsul e formed of C.T. cells and C.T. fibres. 2- Thin C.T. Septa which divide the gland into lobes and lobules. 3- Reticular C.T. Network present in the backgro und of the gland. B-The Parenchyma Of Subma ndibula r Gland Is Formed Of Secretory Acini and Excretory Ducts: - The Secretory Acini Arc Of Three Types: Serous, M uco us and mixed Mucose rous

1- The Serous Acini : They are the most commo n ac ini , they are simi lar in their structur e and function s to those of parotid gland

2- The Mucou s Acini : -They are group of cubo idal cells surroud ning a wide lumen. -They are enclose d from outside by baseme nt membra ne and myoepi thelial ce ll s (Basket Cells) -Their cytoplas m is lightly stained due to dissolve d mucinog en granule s . - Their nuclei are flattene d and basal in position . -The intercel lular secretor y canalicu li are not apparen t. - The mucous acini secrete mucous salivary secretio n Crescent Of Gianuzzi

Duct Serous Acini

Submandibular Salivary Gland -7-

3- The Mixed Mucoserous Acini: - They are mucous acini which are capped by few serous cells - The serous cells form the Crescent Of Gannuzzi. -They secrete serous and mucous salivary secretion.

The Ducts Of Submandibular Glands are Sim il ar to those of parotid glands. The main ducts open into the f loor of the mouth cavity. Serous Demilunes

Mucous Acini Acini

Sublingual Salivary Gland

The Sublingual Salivary Glands - They are mixed tubulo- acinar glands present in the floor of the mouth cavity. - Each g land is formed of a C.T. stroma and a parenchyma of secretory epithelial cells in the form of acini and ducts.

-The C.T. Stroma is formed of thin C.T. capsule, thin C.T. Septa and reticular C.T. in the background of the gland.

-The Parenchyma Of Sublingual Salivary Glands is formed of serous, mucous, mucoserous acini and duct system.

- The Acini Are The Following : a- Mucous Acini which are the majority and are similar to those of submandibular salivary gland.

-8-

b- Serous Acini are few in number and are similar to those of parotid gland. c- Muco-S erous Mixed acini which are formed of serous cells forming clemilunes or crescents of Gannuzzi on the mucous acini.

-These acini secrete about 5% of the total salivary secretion . The Ducts Of Sublingual Salivary Glands are similar to those of ·parotid gland.

The Digestive Tract The Digestive Tract includes: Oesophagus, Stomach, Small and Large Intestine, Rectum and Anal Canal.

The Oesophagus - It is about 25 em long, it connects the pharynx with the stomach . - Its wall is formed of : Mucosa, Submucosa, Musculosa and Adventitia. 1- The Mucosa Is Ij'ormcd Of: Stratified Squamous Epithelium 1 Epithelium, C.T. and Smooth muscles. Lumen __.. •• a- Epithelium: Non Keratinized stratified squamous . b- Corium Of C.T.: It contains nerves , vessels, blood lymphatics and mucous glands called Cardiac Oesophageal Glands. c- Muscu laris Mucosa: It 1s Oesophagus (T.S) formed of inner longitudinal and outer circular smooth muscles. 2- Submucosa: It is formed of C.T. rich in B.V. nerves and lymphatics. In man and clog it contains mucous glands.

__

-9-

3- Musculosa: Skeletal muscles are present in the upper third, skeletal and smooth muscles are present in the middle third, while the lower third of oesophagu_s contains smooth muscles only. All muscles are involuntary and are arranged as inner circ ul ar and outer longit udinal. 4- Fibrosa or Adventitia: It is formed of C.T. with B.V. , lymphatics and nerves . Changes At The Castro-oesopha geal Junction 1The Stratifed Squamous epithe lium Changes into Simple Columnar. 2The oesophageal glands disappear at the junction and are replaced by the branched tubular Gastro-oesophageal Junction glands of the stomach. 3- The thin muscles of oesophagus are replaced by the thick muscles of stomach.

The Stomach - 1t secretes HCI , mucus , pepsin, renin and lipase enzymes. - lt also secretes the intrinsic factor, serotonin and endorphin substances. - ft secretes somatostatin enteroglucagon and gastrin hormones. - rt mixes, digests and absorbs certain food. - The wall of stomach is formed of: Mucosa, Submucosa, Musculosa and Serosa. - The Mucosa is formed of: Gastric glands, lamina propria of C.T. and muscularis mucosa.

-10-

Mucosa Of Stomach - It is lined with simple columnar cells which secrete mucus.

Gastric Pits are small depressions in the mucosa of stomach through which gastric g lands open. Gastric Glands are of 3 types according to the anatomica l regions of the stomach .

1- Cardia Gastric Glands present in the cardiac region of stomach. They are lined with co lumnar and very few parietal ce ll s.

2- Fundic Gastric Glands present in the fundus and body of stomach. 3- Pyloric Gastric Glands present in the pyloric part of stomach.

The Fundic Gastric Glands. - They are present in the fundus and body of stomach. -

They

are

branched

tubular

glands. - They are separated from each othe r by C.T. corium . - They open into gastric

pits

which are depressed openings in the gastric mucosa.

Each Fundic Gland Is Formed Of:

l- Isthmus lined with columnar ce ll s, parietal and stem cells

2- Neck lined with mucou s cells and parietal cells

3- Base lined with chief cells, parietal

cells

entero-endocrine cells.

and

Fundic Gastric Glands

The Following 6 Types Of Cells Are Present In The Gastric Mucosa Of The Fundus And Body Of Stomach:

-I 1-

1- Surface Mucous Columnar Cells:- They are simple columnar cells with basal oval nuclei. - They have surface microvilli. - Their apical cytoplasm contains mucinogen granules. - They secrete neutral mucus to protect the gastric mucosa from the acidity of HCl. 2- Undifferentiated Stem Cells:- They are present mainly in the necks of gastric glands . - They are columnar cells with pale cytoplasm and basal oval nuclei . - They can differentiate into peptic cells, parietal cells, surface columnar cells and to mucous neck cells. 3- Mucous Neck Cells: - They are present in gastric pits and necks of gastric glands. - They are columnar cells with basal oval nuclei. - Their apical cytoplasm is rich in secretory granules. - Their surfaces are covered with microvilli. - They secrete acidic mucus. 4- Parietal Or Oxyntic Cells : - They are present mainly in the gastric glands of fundus and body of . stomach. -They are peripheral in position (Parietal). - They are triangular cells with acidophilic cytoplasm (oxyntic). - They have central rounded nuclei. - They have intracellular canaliculi and microvilli. - They have many mitochondria, small Golgi bodies and very few secretory granules. -They secr.ete HCI and the intrinsic factor. -12-

5- The Peptic = Chief= Zymogenic = Central Cells:- They are the numerous cells= Chief Cells. - They are mainly present in the bases of gastric glands. -They are columnar cells with rounded basal nuclei. - Their apical cytoplasm is rich in acidophilic zymogen granules, while the base of their cytoplasm is rich in basophilic mitochondria . - Chief cells are covered with short microvilli.

- Chief Cells secrete pepsinogen, rennin and lipase enzymes. 6- Enterocndocrinc =Argentaffi n Cells:- They are present in the fundus and pylorus of stomach, present also in small and large intestine , common bile and pancreatic ducts. - They are pyramidal cell with basal rounded nuclei and basal secretory ----;:--, Pyloric granules. Gastric Pits There are several types of entero endocrine cells in the gastric Mucous the secrete mucosa which : Columnar I following hormones. Cells 1- G-Cells secrete Gastrin Hormone Entero secrete Hormone. -Glucagon 3- E- Cells secrete Endorphin Hormones. 4- SER- Cells secrete Serotonin Hormone. 5- S-Cells secrete Somatostatin Hormone.

2-

EG-Cells

2- The Pyloric Gastric Glands - They are short simple branched tubular glands. - They are not crowded . - They have wide deep gastric pits. - They are coiled glands with wide lumina.

- 13-

:-r-:'3~.......

L.s. And T .s.

In Pyloric Glands

- The Pyloric Glands Are Lined With:1- Mucous Columnar cells with flat basal nuclei. 2- Few parietal cells. 3- Entero-endocrine cells similar to those of fundic glands. · Submucosa Of Stomach (Fundus and Pylorus) It is formed of C.T. rich in B.V., nerves, lymphatics, leucocytes and mast cells. Musculosa Of Stomach - It is formed of smooth muscles separated with nerves. - In the fundus the muscles are arranged as inner oblique, middle circular and an outer longitudinal l~yers. -In the pylorus the muscles are arranged as thick inner circular and an outer longitudinal layers. Serosa Of Stomach: It is the peritoneal covering of the stomach formed of simple squamous mesotheliuem, C.T., B.V. and nerves~ Differences Between Fundus And Pylorus Fundus

Pylorus

1- Fundic glands are long branched 1-Pyloric glands are short branched tubular.

coiled tubular.

2- Gastric pits are narrow and short. 2- Pyloric pits are wide and deep. 3- Diffuse lymphocytes are present 3- Small lymph follicles are present between the glands.

between the glands.

4- Six types of cells line fundic 4- Five types of cells line pyloric glands: Surface cells, Stem cells, glands:Surface cells, Stem cells paNeck cells, parietal cells, Chief cells rietal cells, Chief cells and Enteroand Entero-Endocrine cells.

Endocrine cells.

5- High folded mucosa.

5- Less folded mucosa.

6- Three Muscle Layers are present 6-Two Muscle Layers are present in in the wall of fundus.

the wall of pylorus.

-14-

The Pyloro-Duodenal Junctiop. Is Characterized By: 1- Appearance of intestinal villi. and crypts in the small intestine. 2- Appearance of goblet cells in villi and crypts of intestine. 3- Appearance of Bruner's glands in submucosa of duodenum. 4- The muscles are more thin in intestine than in stomach.

The Small Intestine -The small intestine is composed of 3 parts: Duodenum, Jejunum and Ileum. - It has a digestive function, absorption of useful substances and secretion of intestinal enzymes and hormones. - The Wall Of Small Intestine Is Formed Of: 1- MucO!ia

2-Submucosa.

3- Musculosa

4- Serosa

Mucosa Of Small Intestine - The mucosa is formed of: 1- Intestinal villi and crypts. 2- C. T. Corium containing; blood vessels, lymphatics nerves and leucocytes.

3- Muscularis mucosa: Smooth muscles arranged as inner circular and outer longitudenal.

The Intestinal Villi -They are leaf-like projections of the mucosa. - They ':ire covered with columnar cells, goblet cells and very few entero-endocrine cells.

- C.T. C~rium is present under the basement membrane of the covering epithelium, it contains lymph vessels called central lacteals, nerves, smooth muscles and fenestrated blood capillaries. -15-

Types Of Cells Covering The Intestinal Villi l- Absorptive Columnar Cells: .....-, ....., / \Intestinal Villi - They are columnar cells with basal ..... oval nuclei. -They have acidophilic brush surfaces due to presence of long microvilli. Their cytoplasm IS rich m mitochondria, rough endoplasmic reticulum, Golgi bodies , and few free ribosomomes. These cells are held together by different junctional complexes to form a sealed covering layer. - These cells are specialized for absorption of useful substances ( and secretion of lactase, sucrase .. and isomaltase enzymes.

2- Goblet Cells:

/

j

·

Simple

Central Lacteal

Intestinal Crypts Paneth ..· •Cells

f Intestinal Villi And Crypts · th - Th ey are presen t m e mucosa o small and large intestine. - They are unicellular mucus secreting glands. - Each goblet cell has an expanded apex full of mucus and a narrow base which contains a darkly stained nucleus. - The base of each cell contains mitochondria, Golgi complex and endoplasmic reticulum.

The Following 2 Types of goblet cells are present in the intestine a- Mature Goblet Cells present on the villi b- Oligomucous Immature Goblet Cells present in the crypts. They develop from stem cells, they have few mucus secretory granules. - Goblet Cells secrete acidic glycoprotein mucus secretion which prevent bacterial invasion to intestinal mucosa.

-16-

3- Entero-endocrine Cells: -They are very few on the villi but more present in the crypts. - They are pyramidal cells with basal Golgi and secretory bodies. - They secrete peptide hormones as secretin , somatostatin , serotonin · and endorphin.

The Intestinal Crypts Of Lieberkuhn -They are simple tubular glands. -They are present in the C.T. corium of the mucosa of small intestine

Types Of Cells Lining The Intestinal Crypts 1- Simple Columnar Absorptive Cells. 2- Mature Goblet Cells. 3- Oligomucus Immature Goblet Cells. 4- Entero-endocrine Cells which secrete: Secretin, Neurotensin, Motilin, Cholecystoki nin , Pancreozymi n and Endorphin hormone.

Intestinal

Crypts

5- Stem Columnar Cells : - They are columnar cells with basal oval nuclei. - They have few mitochondria , small Golgi and few ribosomes.

- They are present at the bottoms of intestinal crypts . -They are pyramidal cells with broad bases and narrow apex. - They have basal oval nuclei. - Their cytoplasm is rich in zinc, mitochondria and ribosomes. -Their apical cytoplasm is rich in zymogen granules. -They secrete intestinal digestive enzymes and Lysozyme.

-l7-

7- Caveolate Cells: · - They are present in small and large intestine. - They have broad base and narrow apex. · - They have microvilli on their surfaces. -They have rounded basal nuclei. - They act as chemoreceptor cells . N.B. The mucosa of small intestine is rich in lymphocytes, globule leucocytes and M cells. These M cells play an important role in the immune system of the body.They are called Antigen Presenting Cells.

2-Submucosa Of Small Intestine It is formed of C.T. rich in B.V., nerves and lymphatics. Brunner's glands are present in the first part of duodenal mucosa.

3- Musculosa Of Small Intestine It is formed of smooth involuntary muscles arranged as inner circular and outer longitudil)al separated with Auerbach's Plexus of nerves.

4- Serosa Of Small Intestine It is formed of areolar C.T. covered with simple squamous mesothelium.

Differences Between Duodenum, Jejunum and Ileum Characteristics Of Duodenum - Its villi are broad, long and leaf-like. They are covered with few goblet cells. The submucosa contains Brunner's glands.

Brunner's Glands They are coiled tubular glands. They secrete alkaline mucus to protect the intestinal mucosa from the acidity of gastric chyme. Bruner's glands secrete urogastrone hormone which inhibit''HCl secretion and stimulate renewal of intestinal cells.

-18-

Characteristics Of Jejunum - [ts vi IIi are short and tongue-shaped.

Villi

- Many gobl et ce ll s are present in its mucosa . Peyer's

- No Brunner 's glands nor . Peyer's patches are

Patch

present in jejunum.

Characteristics Of Ileum ' - Its villi are long, slender

Mucosa Of Ileum

and fin ger- like.

- Presence of Peyer's patches between the crypts of ilium. They are lymphoid follicles , which play an important role in the immune system.

The Large Intestine - Functions: Its Cells absorb fluid of the intestinal contents . - Its goblet cells secrete abundant mucus. - Its Entero-endocrine cells secrete certain intestinal hormones.

- The Large Intestine Is Formed Of: Mucosa, Submucosa, Musculosa and Serosa

The Mucosa Of Large Intestine :

obJet Cells

- lt has no villi.

:ri.fl~...f~~~ Intestinal

crypts (gland-s) with C.T. rich Lymphatics and nerves .

- 19-

Glands

- The crypts of large intestine are lined with. 1- Simple Columna r Absorpti ve Ce ll s.

2- Many Goblet Cells. 3- Few Entero-e ndocrine Cells . 4- Col umnar Stem Cells. ·.B. There is no Paneth Cells. 'fhc Submuc osa: It is formed of C.T., B.V. nerves and Solitary

lymphoid follicles. The Musculosa: It is formed of continuous inner circular, while the outer longitudinal muscles are present in 3 bundles called taenia coli. The Serosa: It is formed of

C.T. and simple squamou s

Mucosa

mesothel ium.

Characteristics Of Vermiform Appendix

Lymphoid Follicles

- It has a narrow irregular lumen. The

mucosa

contains

many lymphoid follicles . - The crypts are very short and very few are They columna r

in number. lined cells,

with; few

Human Appendix

goblet cells and few entero-en docrine cells. - There is no muscular is mucosa. ~ The musculo sa is thin.

- There is no taenia coli on the surface.

-20-

Characteristics Of Recto-Anal Junction The simple columna r cells Many Goblet Cells Covering St. Sq. Epith. of the rectum Of Anal Canal change into stratified columna r, then Many into stratified squamou s at its Lymphocytes opening on the skin. The crypts of the rectal ...,. Recto-anal Junction mucosa disappea r in the anal canal. - The muscular is mucosa disappea rs at the anal part. - The inner and outer circular smooth muscles form the internal sphincter . -The external anal sphincte r is formed of skeletal voluntary muscles. Differences Between Small And Large Intestine Small Intestine Large Intestine 1- It incl udes; duodenum, jejunum 1- It includes; Caecum, colon and and ileum. rectum. 2- Its mucosa has vi ll i and crypts. 2- Presence of crypts with no villi. 3- Paneth cel ls are present m its 3- No Paneth cells. mucosa 4- Globule leucocytes and M-cells are 4- Many lymphocy tes and lymph phagocytic ce lls in the mucosa follicles are present in the mucosa. 5- Submuco sa of duodenum contains 5- No glands and no lymphoid Bruner's glands and Peyer's follicles in the submucos a. patches· are present in mucosa of · ileum. 6- No taenia coli or appendice s 6- Presence of taen ia coli and epiploica on the outer smface. appendice s epiploica on the outer smface.

-21-

The Liver - It is the largest gland in the body. -It is a compoun d tubular mixed gland. - It secretes bile through bile ducts. - It also secretes plasma protein , lipoprotein and glucose directly into the blood. -It is formed of C.T. Stroma and Parenchyma of Liver cells

The C.T. Stroma of liver is formed of: Capsule: It is formed of C.T. cells and fibres covered by peritoneu m. Trabeculae: They are formed of C.T. cells and fibres. They are very thin in human and very thick in certain animals. Reticular network: They form a network which is formed of reticular · cells and fibres.

The Parenchyma Of Liver Is Formed Of: 1- Plates and cords of liver ce1ls = hepatocy tes. 2- Blood vessels (arteries, veins and sinusoids ). 3- Bile ducts (intra and extra hepatic ducts). -The parenchy ma of the liver is organize d in the following descripti ve lobules. 1- Portal Tract: It is the C.T area present between 3 hepatic lobules. It contains: a- Branch of hepatic artery. b- Branch of portal vein. c- Bile duct. d- Lymph vessel.

Portal Tract In Liver -22-

2- portal Lobule: It is a triangular area of liver tissue cornered between 3 central veins with a portal tract in its centre. 3- Liver Acinus: It is a diamond-shaped area of liver tissue surrounding a branch of hepatic artery and a branch of the portal vein. The liver

cells near these vessels are richly supplied with blood, while the liver ce lls which are present in the periphery of the liver acinus receive less amounts of oxygen and nutritive materials.

4- Classic Hepatic Lobule -It is a hexagonal mass of liver tissue that surrounds a central vein. - It is formed of plates or c01·ds of liver cells which radiate from the central vein. - The hepatic plates are formed of two or more rows of liver ce ll s. The

rows

of liver

cells

enclose between them bile canaliculi which carry bile to the bile ductules. - The li ver plates or cords are surrounded by blood sinusoids

and

by

perisinusoidal spaces Called Spaces Of Disse

Classic Hepatic Lobule

- The Spaces Of Disse Contain : a- Supporting reticular fibres . b- Fat cells called adipo'c ytes. c- Blood plasma. d- Microvilli projecting from the liver cells.

-23-

The Hepatic Blood Sinusoids - They are present between the hepatic plates . - They are lined with fenestrated non-continuous simple squamous endothelium and with Von Kupffer Cells

The Von Kupffer Cells - They are phagocytic cells present in the wall of hepatic blood sinusoids - They have micro villi and produce pseudopodia . - Their basophilic cytoplasm is rich in lysosomes and haemosiderin granules - They can phagocytose micro-organisms, destructed hepatocytes and old blood cells.

The Liver Cells Or Hepatocytes - The hepatic cells are arranged as branching plates or cords that radiate from the central veins of classic hepatic lobules . - Blood sinusoids run in between the liver plates, they are lined with endothelial cells and von Kupffer cells. - Bile canaliculi run in between hepatocytes, they are lined with the cell membranes of two adjacent hepatocytes.

- Each Liver Cell Therefore bas three surfaces: a- A surface facing blood sinusoids rich in microvilli. b- A surface facing bile canaliculi rich in microvilli. c- A surface facing the adjacent liver cell with many junctional complex.

Characteristics Of Liver Cells Under ElM : -Mitochondria are up to 1000 and are of various shapes. ·- Ribosom es are either free or attached. - Lysosomes are many and contain granules.

-24-

- Rough endoplasmic reticulum are well developed. - Smooth endoplasmic reticulum are well developed. - Golgi apparatus is present near the nucleus. - Peroxisomes are rich in enzymes for fatty acid oxidation. - Peribiliary bodies are present near bile canaliculi. -Liver cells are rich in glycogen, fat and microbodies. - The Nuclei Of Liver Cells: - They are vesicular rich in nuclear fluid. -About 25% of liver cells contain 2 nuclei. - Each nucleus contains clear nucleolus.

Different Duct Systems For Biliary Passages 1- Bile Canaliculi present between the rows of liver cells and are lined by the wall of liver cells.

.

2- Canals Of Hering lined by simple cubical and are present· at the periphery of classic hepatic lobules. 3- Preductules are present also at the periphery of hepatic lobules and are lined with simple cubical cells. 4- Bile Ducts are lined with simple cubical and are present in the C.T. of portal tracts. 5- Intra-hepati c Bile Ducts are lined with simple columnar. 6- Extra-hepatic Bile Ducts are, lined with simple columnar surrounded by C.T. and smooth muscles. 7- Common Bile Duct is lined with simple columnar and with entero-endocrine cells. Gall Bladder: It is a thin walled sac that stores and concentrates bile.

Its wall is formed of: a- Mucosa: It is highly folded lined with simple columnar cells which -25-

have long microvilli, Mucosa of gall bladder has no crypts, no goblet cells, no glands and no muscularis mucosa. b- Musculo sa formed of smooth muscles. c- Serosa formed of C.T. and peritoneum.

Functions Of The Liver: 1~ It forms albumen, prothrombin and fibrinogen. 2- It forms lipoproteins. 3- It secretes bile. 4- It stores lipids, carbohydrates and vitamins (A,D,E,K). 5- Deamination of amino acids to remove it in the form of urea. 6-Detoxification and inactivation of toxic drugs. 7- Formation of immunoglobulins (IgA & IgM).

The Pancre as - It is a mixed gland with exocrine and endocrine functions. . '- It is present in the concavity of the duodenum. - It is formed of C. T. Stroma and Parench yma of exocrine pancreatic acini and ducts and endocrine cells called Islets of Langerh ans. The Connect ive Tissue Stroma Of Pancrea s is formed of: Capsule formed of C.T. cells and fibres. Trabecu lae are thin formed of C.T. cells and fibres. Reticula r C.T wltich support the acini, ducts and the islets.

The Pancre atic Acini - They are lined with pyramidal cells with few microvilli . ·- The cells are adherent together by different junctional complex to . prevent release of enzymes to intercellular spaces. - Each cell has apical acidophilic zymogen granules. - Each cell has basal basophilic striations rich in RNA, Rough Endoplasmic reticulum and mitochondria. '-26-

- Golgi apparatus is present supranuclear in position. - The nucleu s is rounded and basal in position.

Acini

- The acini are not surrounded by myoepithe li a l ce ll s.

Islet Of Langer han

- The pancreatic acini secrete: Trypsin ogen,

chymotrypsinogen ,

peptidases, nuc leases, lipase and amylase enzymes. The secretion is controlled

by

secretin

and

nervous

and

B. V.

by

cholecystokinin

hormones.

Pancreas

The pancreatic Ducts are the followings: 1- Intercalated Ducts: They are telescoped in the pancreatic acini and are lined by simple cubical epithelium. These cubical cells appear in the centre of pancreatic acini and are called Centro -Acinar

Cells 2- Intra-lobular Ducts: They are very narrow and few m number. They are lined with simple cuboidal cells.

3- Inter-lobular Ducts: They are lined with simple col umnar cells. 4- Main pancreatic Duct: It is lined with simple columnar with some goblet and entero-endocrine cells .

The Islets Of Langer han~ - They are the endocrine portion of the pancreas. - They appear as pale-stained areas.

-27-

- They are more present in the tai l of pancreas. - They are formed of reticular C.T. stroma and a parenchyma of endocrine cel ls. - They are rich in fenestrated blood capillaries to carry the secreted hormones. The Following Types Of Cells Are Present In The Islets Of Langerhans:

Alpha(A), Beta, (B) C-Cells, Delta (D-Cells), F-Cells and Ganglion

~~·

Nerve Cells.

1- Alpha Cells or A Cells of The islets : They

constitute

about 20% of the '

t

Islet cells. ··· They are oval in

ancreatic Acini

shape with rounded nuclei.

Islet Of Langerhans - They contain few mitochondria and small Golgi. - Their granules have dense central part and pale peripheral part. - They secrete Glucagon Hormone which can raise blood sugar. It is an anti -insulin hormone.

2- Beta Cells or B-Cells of the islets : - They constitute about 70% of the islet cells. - They are oval cells with rounded nuclei. - Their cytoplasm is rich in mitochondria, Golgi bodies and rough endoplasmic reticulum. -28-

- Their granules have crystalloid appearance. - Beta Cells secrete Insulin Hormone which lower the blood sugar . level. Decrease insulin secretion causes Diabetes Mellitus Disease.

3- C-Cells of the islets of Langer hans -They are very few in number. . - They are oval cells with rounded nuclei. - They have non-granular cytoplasm. - Their cytoplasm has few mitochondria. - C-Cells are considered as reserve stem cells for the renewal of the other islets cells. 4- Delta or D-Cells of the islets:

- They are very few in number. - They are oval cells with rounded nuclei. - They contain pale large secretory granules. - They ;·ecrete Somatostati n Hormone which inhibits the secretion of: Insulin, Glucagon, Pancreatic Polypeptides and Growth hormone.

5- F -Cells or Pancreatic Polypeptide Cells (PPC) - They are very few in number. - They are oval cells with rounded nuclei. - They contain few pale granules. -They are also present among the pancreatic acini. - They secrete Pancreatic Polypeptides.

6- Autonomic Ganglion Nerve Cells in the islets : - They are multipolar nerve cells. - They are present in groups in the islets. - Their cytoplasm has Nissl granules.

-29-

-Their nuclei are rounded and central. -They can be stained with silver. - They have a nervous control over pancreatic secretion. Insulin secretion is stimulated by parasympathetic and inhibited by sympathetic stimulations. Differences Between parotid And pancreas Parotid

Pancreas

1- Two Exocrine glands

1- Single mixed gland .

2- Covered with thick capsule

2- Thin capsule and peritoneum.

3-

Its

Serous

acm1

are

rich

m 3- Acini have apical acidophilic

basophilic granules. 4-

Bave

and basal basophilic granules.

secretory

ducts

no 4- Have no secretory ducts.

centro-acino e cells 5- Intercalary ducts are not telescoped 5- Intercalary ducts are telescoped in in the acini. the acini. 6- Few endocrine cells are present in 6- Five Types of endocrine cells are parotid ducts secrete Parotin present in the islets of Langerhans.

Hormone. 7- Few ganglion nerve cells.

7- Many ganglion nerve cells.

Zona Glomerulosa

Cortex ~~~ il'

Medualla '--=-:::-;;:;;.~~:...__~

,..:.--;.~-r-

Suprarenal Gland -30-

Zona Fasciculata Zona Reticularis Suprarenal Medulla

The Endocrine System - They are certain glands, groups of cells and isolated cells which secrete hormones directly in the blood. - They have no ducts . - They have fenestrated blood capillaries to carry secreted hormones. - The endocrine and the nervous systems regulate all metabolic activities of all body organs. - Their secretions are controlled by the autonomic nervous system and by the feed back mechanism.

The Endocrine System Includes : 1- Endocrine Glands: Suprarenal, Pituitary, Thyroid and parathyroid Glands. 2- Endocrine Masses Of Cells Present In: Pancreas, Testes, Ovaries, Kidneys, Placenta, Thymus, Hypothalamus, Pineal body and Respiratory System. 3- Isolated Endocrine Cells Present In : Stomach, Intestine and parotid gland. They are called APUD Cells (Amine Precursor Uptake Decarboxylation Cells) or Entero-Endocrine Cells.

The Suprarenal Glands (Adrenals) - There are 2 adrenal glands which are present over the upper poles of both kidneys. - Each gland is formed of C.T. Stroma and a Parenchyma of secretory cells arranged as peripheral Cortex and central Medulla.

- The C.T. Stroma Is Formed Of: a- CapsuleJormedof C.Lcells and fibres.

-31-

b- Trabeculae formed of C.T. which descend from the capsule. c- Reticula•· C.T. which forms the background of the g land. - The Parenchyma Is Formed Of

ill'!

Cortex and Medulla :

The Suprarenal Cortex - It develops from mesoderm and secretes Stet·oid Hormones .

- It Includes The Following 3 Zones :

1- Zona Glomerulosa : -It is present under the C.T. capsule. - It is formed of columnar cells with oval nuclei. - The cells are arranged in arches or glomeruli. -The ii·

cytoplasm

basophilic

1s

rich

m

granules.

- Their cytoplasm is rich m smooth endoplasmic t:eticu lum , mitochondria and well-developed Golgi apparatus.

Zona

Glomerulosa

Minet·alocorticoids which

regulates

Cells

Secrete

(Aldosterone) sodium

and

potassium ion levels. It also regulates blood Pressure.

Suprarenal Gland -32-

2- Zona Ji'asciculata : - It is the widest zone of the adrenal cortex. - It is formed of cuboidal cells with central rounded nuclei. -The cells are arranged in cords. - The cell cords are .separated by blood sinusoids. -The cytoplasm is rich in smooth endoplasmic reticulum, mitochondria, Golgi body and fat droplets. - The stained .cytoplasm appear vaculated due to dissolved fat. So these cells are called Spongiocytes. - Zona Fasciculata Cells Secrete Glucocorticoids.

3- Zona Reticularis : -It is formed of cuboidal cells with central rounded nuclei. - The cells are arranged in anastomosing cords.

-The cords are separated by blood sinus.oids. - The cell cytoplasm is rich in smooth endoplasmic reticulum, mitochondria, Golgi apparatus and fat droplets. - Zona Reticularis Cells Secrete Glucocorticoids and Androgens.

The Suprarenal Medulla - It is present in the centre of the suprarenal gland . from ectoderm and secretes Catecholamines. - It develops \ - It is formed of Chromaffin cells and Ganglion nerve cells.

1- Chromaffin Cells Of Suprarenal Medulla : - They are polyhydral cells with central rounded nuclei. -They are present in groups surrounded with blood sinusoids .. - Their cytoplasm is basophilic rich in fine granules. - They are rich in mitochqndria and free ribosomes.

-33-

- There are 2 types of Chromaffin Cells : a- Adrenaline Sec ret ing Ce ll s with pale granules . b- Noradrenaline Secreting Cells with dark granules .

2- Ganglion Nerve Cells Of Suprarenal Medulla : -They are branch ed ne rve ce ll s with central nucl e i. - They are scattered between chromaffin ce ll s. -They are innervated by preganglionic choline rg ic fibres. -They act as sy mpathetic ganglion. 3- Many Lymphocytes are present also in the Suprarenal medulla ..

The Pituitary Gland - It is a small endocrine gland present at the base of brain. - It is under the control of hypothalamu s. Its

hormonal

control s

certain

sec retion endocrine Pars

glands. It is formed of anterior and posterior lobes.

The anterior lobe

IS

called

adenohypophysis. It dev leops

~~- Pars

~:!,;::~..-.;=~

from the roof of oral ectoderm

Intermedia

(From Rathke's Pouch).

- The posterior lobe is called

...

neurohypophysis. It develops from the neural

r

ectoderm

(From the floor of the third

·. r .

Pituitary Gland

ventricle).

-34-

The Anterior Lobe Of Pituitary Gland It includes the following parts 1- Pars Distalis

2- Pars Tuberalis

3- Pats Intermedia

Pars Distalis Of Pituitary Gland - Its stroma is formed of thin C.T. capsule and a central reticular network. - Its parenchyma is formed of cords of cells separated by blood sinusoids. -There are 2 groups of cells. 1- Chromophil Cells including acidophil and basophil cells. 2- Chromophobe Cells which are inactive forms of chromophil cells.

I- Chromophil Cells Of Pars Distalis There are 2 types of chromophil cells: 1- Acidophil Cells

2- Basophil Cells

Acidophils or Alpha Cells Of Pituitary Gland - They are about 35% of chromophil cells.- They are of 2 types: A- Somatotrophs. . B- Mammotrophs.

A- Somatotroph or Soi:natotrope Cells: - They are oval cells with rounded !luclei. - Their cytoplasm is rich in rough . endoplasmic reticulum and dark. granules. - They can be stained orange with orange G stain . - They secrete Growth Hormone (Somatotrophin) .

B- Mammotroph Cells : - They are spindle - shaped cells with oval nuclei. - Their cytoplasm is rich in small granules and rough endoplasmic reticulum.

- They secrete Prolactin or Lactogenic Hormone. - During pregnancy the size of these cells may increase and are called

Pregnancy Cells.

-35-

Basophils or Beta Cells Of Pituitary Gland - They const itute about 15 % of the chromophil cells. They can be differentiated by their granules through E/M stud ies.

-There are 3 types of basophils: Thyrotroph, Corticotroph and Gonadotroph Cells.

1- Thyrotroph Cells -They are rounded ce ll s with rounded nuclei. -Their cytoplasm is rich in basophi lic gran ules. - They secrete Thyroid Stim ulating Hormone (TSH) wl1ich regulates ·the functions of thyroid gland .

2- Corticotroph Cells -They are oval cells with eccentric rounded nuclei . - Their cytoplasm is rich in basophilic granules. - They are rich in endoplasmic reticulum, mitochondria and well developed Golgi apparatus.

-These cells secrete: Adreno-CorticoTrophic Hormone (ACTH) which stimulates secretion of glucocorticoids zona

from

fasciculata

of

suprarena l gland. They

also

secrete

Melanocyte Stimulating Hormone (MSH) which regulates

formation

distribution

of

also

--~----=-~ Chromophobe

melanin

pigments in the body . They

Cells

and

secrete

Cells

Pars Distalis Of Pituitary Gland a

lipotropic Hormone which regulates iipid metabolism. -They also secrete Beta Endorphin which is a potent Opioid Peptide

-36-

3- Gonad otroph Cells - They are rounded cells with rounded nuclei. - !heir cytoplasm is rich in basophi_lic granules. - They have well-developed Golgi apparatus and rough endoplasmic reticulum.

Conad otroph Cells Are Classified Into a·- Follicular Stimulating Hormo ne Secretory Cells : These cells secrete Follicular Stimulating Hormone (F.S.H.) which promotes growth and maturation of ovarian follicles. b- Interst itial Cell Stimulating Hormo ne Secretory Cells: They secrete I.C.S.H which stimulate Lyedig 's cells of testes to produce testosterone hormone. c- Lutenizing Hormone Secretory Cells :They secrete Lutenizing Hormone (L.H.) which pr_omotes growth and maturation of Corpus Luteum in females. as a sort of Castra tion Cells. : Removal of both testes I in males , treatment of cancer prostate will lead to increase in the size of Gonadotroph cells. ·Their collected colloidal secretion will push their

.

.

. nuclei towards the periphery. These changed Gonadotroph cells are now called Signet Ring Cells or Castration Cells.

II-Chro moph obe Cells Of Pars Distalis - They constitute about 50% . - They have no affinity to histological stains. - They are polygonal cells with few granules. -Some of these cells are capable to differentiate into secretory cells.· - Other cells are considered as macrophage cells.

-37-

2- Pars lntermed ia Of Anterior Pituitary - It is formed of polygonal cells with rounded nuclei. - Their cytoplasm contains few basophilic granules. - The cells are arranged in cords or follicles. The Cells Secrete Melanocyte Stimulating Hormone (MSH) which promotes melanin formation and distribution.

3- Pars Tuberalis Of Pituitary Gland - It is the upward extension of the pars distalis. - It is very rich in blood vessels. - Its cells are cubical with central nuclei. - Their cytoplasm is basophilic. - The cells are ananged in cords or follicles. - The function of cells is unknown.

The Posterio r Lobe Of Pituitar y Gland (The Neurohypophysis) The Neurohypophysis Includes :a- Pars Nervosa b- Infundibulum: It is formed of nerve fibres which connect the posterior lobe of pituitary with the-hypothalamus. These nerve fibres carry the secreted hormones of the hypothalamus to pars nervosa of pituitary gland.

Pars Nervosa Of Pituitar y Gland - It has no hormonal secretion. - It has no nerve cells. - It is rich in blood capillaries.

-38-

- The Following structur es are present in the Pars Nervosa: 1- Non-myelinated nerve fibres which are the axons of the secretory nerve cells of the hypothalamus. 2~ Blood capillaries and blood sinusoids. 3- Pituicyt e Cells : They are branched cells with multiple processes. They are supportive cells similar to neuroglia. 4- Herring Bodies: They are acidophilic materials found close to terminal ends of nerve fibres. They are tdle accumulated hormones secreted by the nerve cells of the hypothalamus and are called Neurose cretion.

The Following Are The Hormones Which Are Secreted By The Nerve Cells Of The Hypothalamus (Neurosecretion) 1- Antidiuretic Hormone (ADH) =Vasop ressin Hormone - It promotes water absorption by the kidney tubules. - Deficiency of this hormone gives rise to Diabetes Insipidus

2- Oxytocin Hormone - It stimulates uterine contraction during labour. - It stimulates milk ejection during lactation. 3- Thyrotr opin Releasing Hormon e (TRH). It ·stimulates thyroid hormone secretion through the release of TSH 4- Cortico tropin Releasing Hormon e (CRH) .It stimulates corticosteroid secretion through the release of ACTH. 5- Gonado tropin Releasing Hormon e (GRH) . It stimulates gonadotrophin secretion. 6- Somato tropin Inhibitin g Hormon e (SIH). It inhibits somatotropin hormone secretion. 7- Prolacti n Inhibitin g Hormon e (PIH). It inhibits prolactin secretion. -39-

Thyroid Gland - ft is an endocrine gland present in the neck. - It is for med of 2 lobes

c~:mnectecl

by isthmus.

-Enlargement of thyro id gland is called go itre. -The g land is formed of C.T. Stroma and Parenchyma.

- The C.T. Stroma Of Thyroid Gland Is Formed Of: Capsule: The outer caps ul e is the pretracheal fasc ia.

The inner capsule co nsists of fibro-elastic C.T. Trabeculae: They are formed Para Follicular

of C.T. ce ll s and fibres. Reticular C.T: It

forms

a

C-cells

network around thyroid follicles. The parenchyma Of Thyroid Gland:

-It is formed of Thyroid follicles and interfoll icu lar cells

Follicle

The Thyroid Follicles -They are spheri cal in shape.

Thyroid Gland

-They are surrounded with fenestrated blood capillaries . -They are enclosed by thin basement membranes. -The fo llicles arc full of acidophilic colloid.

- Thyroid follicles are lined with the following 2 types of Cells. 1- Principal Follicular Cells . 2- Para - Follicular C-cells.

-40-

1- The Principal Follicular Cells -They are endode rmal in origin. -They are cuboid al cells with rounde d nuclei. - They are adhere nt togeth er by junctio nal comple xes. -They have short microv illi. -Their cytopl asm is basoph ilic. - Their cytopl asm is rich m rough endopl asmic reticul um , mitoch ondria , riboso mes , lysoso mes, Golgi appara tus and apical secreto ry granul es.

-The Principal Cells Secrete Thyroid Hormones (T3+ T4). Thyroid Hormones regulat e normal growth and develo pment, norma l basal metabo lic rate, norma l body temper ature, norma l gonada l develo pment and regula te norma l activiti es of nervou s system .

2- The parafollicular C- Cells - They are ectode rmal in origin. - They are presen t in the wall of thyroid follicle s resting on its basem ent membr ane but they do not reach the luminal surface . - They are cuboid al cells with pale cytopla sm. - They have central rounde d

Para follicular C-cells

nuclei. They

contain

few

Follicular Cells

ribosom es, mitoch ondria , lysoso mes, rough endopl asmic reticul um and Cells Of Thyroid Follicles dense secreto ry granul es .

- C-Cells Secrete Thyro-Calcitonin Hormone which reduce s calcium blood, increas es calcium deposi tion in bone and it increas es calcium uptake by the cells.

-41-

The Para-Thy_f()id Glands -There are 4 parathyroid glands embedded behind the thyroid. - They develop from the endoderm. -Each gland is covered with thin C.T. Capsule - Del icate Reticular C.T. is present in the background of each parathyroid

Types Of Cells In Each parathyroid Gland 1- The Chief or Principal Cells -They consti tute the majority of cells in parathyroid - T hey are polygonal in shape with central rounded nuclei. - There are 2 types of cells; Dark and Light Chief Cells. -Their cytop lasm is rich in glycogen ami fine granules. - Their cytop lasm contains many mitochondria , ribosomes, ro ugh e ndop lasm ic reticulum, lipid and g lycogen granules.

-They Secrete parathyroid Hormone which increases blood calciu m leve l. Absence of this hormone wi ll cause Tetany.

· Principal Cells

2- Oxyphil Cells - T he y- consti tute the minority of parathyroid cells. Their number mcreases after 7th years old.

•. #a

,.

Parathyroid Gland

- They are polygonal cells with rounded nuclei. - Their cytoplasm is rich in acidophilic mitochondria. -Their functions are not yet known.

-42-

The Pineal Body - It is a cone-shaped gland attached by a stalk to the third ventricle. - It is derived from neuro-ectoderm.

- It is formed of: 1- Pinealocytes or Basophil Cells which are branched cells with multiple processes similar to

n~rve

cells. Their cytoplasm is pale

basophilic. They secrete Melatonin Hormone which

regulates

gonadal functions and sleep rhythm. 2- Pineal body contains also, blood capillaries, calcified matrix (Brain Sand) and neuroglia cells.

The APUD Cells - APUD =Amine Precursor Uptake Decarboxylation Cells - They are also called Diffuse Neuro Endocrine Cells (DNEC) -They are derived. from neural ectoderm - They can be stained with silver, so called argentaffin cells. - They are diffusely scattered in stomach, intestine, trachea, bronchi, suprarenal medulla, C-Cells of thyroid, corticotrophs of pituitary, pancreas and hypothalamus, Juxta glomerular cells of kidney and cells of carotid bodies. - These cells secrete Amine and Polypeptide Hormones. - They are considered as highly modified neurones - They contain neurotr~smittors - They contain synaptic-like vesicles with dense core through E/M studies. - These cells have both receptor and secretory functions.

-43-

Urinary System - It includes; 2 kidneys, 2 ureters, one urinary bladder and one urethra. - The kidneys regulate fluid and electrolyte balance through formation and excertion of urine, remove] of waste products and formation of Renin, Erythropoietin and Medullipin Hormones -Each kidney is formed of Uriniferous Tubules.

-The uriniferous tubules are formed of:a- Nephrons: They form and secrete urine. b- Collecting tubules: They concentrate and excrete urine. ~mrJ,~n~~rg~ Malpi~hian Renal Corpuscles

· The Nephron Each Nephron Is Formed Of: 1- Renal Malpighian Corpuscle. 2-

Proximal

and

~~~m~l.- -·?~ _,...,~1.&-·Y,,..,,

Distal

Convol uted T ubules. 3- Loop of Henle

Section In Kidney

Renal Malpighian Corpuscles Each Renal Malpighian Corpuscle Is Formed Of: 1- Bowman's Capsule. 2- Glomerular Capillaries. 3- Afferent and Efferent Arterioles. 4- Supporting Mesangial Cells.

-44-

J)iffcrent Tubules Of Nephron

The Bowman's Capsule - lt surrounds the vascular glomerulu s. - ft has an outer and an inner epithelial layers separated by Bowman's or capsular space. -The outer or Parietal Layer is lined with simple squamous epithelium. -The Inner or Visceral Layer is lined with Podocytes .

The Podocytes -The podocytes line the visceral layer of Bowman's capsule, each cell contains a nucleus, cell organoids and cell inclusions. - They are termed podocytes because they have feet. - Each podocyte is adherent to the outer surface of a glomerula r blood capillary by means of major and minor processes (Feet). - The basement membrane s of both podocytes and of the capillary endotheliu m are fused together to form a thick continuous basal

lamina. -The minor processes of podocytes are implanted on the basal lamina. - There are minute areas between the implanted ends of these minor proceses, these areas of the basal lamina are called Filtration Slits. - These filtration slits are covered by diaphragm s, both the slits and the diaphragm s play an important role in the process of filteration. Parietal ___:~--- Layer

Urinary Pole

_

___.LJo.:::-~ Podocyte

or Viesceral Layer ·_.:~--........,~

Bowman's Capsule ....--......-J....=,.__-'f';: )r

., •

.4

...

,.

Malpighian Renal Corpuscle -45-

Vascular Pole

The Glomerular Blood Capillaries - Each Malpighian renal corpuscle has vascular and urinary poles . - Through the vascular pole an afferent arteriole enters the corpuscle where it divides into many blood capillaries which are in contact with the podocytes. These capillaries then drain into an efferent arteriole. - The endothelium of these glomerular capillaries is fenestrated with pores which are not covered by diaphragms. Each open pore is about 100 nm in diamter. - Outside the endothelium of glomerular capillaries, there is a thick basement membrane formed of The Following 3 Layers : a- A central Dark Layer called Lamina Densa. b- An outer Pale Layer called Lucida Externa. c- An inner Pale Layer called Lucida Interna. - This Basement membrane is essential for filtration selectivity. It is continually renewed by The Mesangial Cells.

The Mesangial Cells - They are adherent to the surface of glomerular blood capillaries. - They are branched cells with basophilic cytoplasm rich in lysosomes and central darkly - stained nuclei. Functions Of Mesangial Cells : 1- They phagocytose the destructed old basement membrane and the foreign organisms which may be present in capillary lumens and in the inter-capillary spaces. 2- They secrete supportive fibronectin substances needed for the renewal of glomerular basement membrane. 3- They secrete a hormone which stimulates secretion of Aldosterone to regulate blood pressure similar to juxta glomerular cells. FunCtion Of Malpighian Renal Corpuscles They form the glomerular filtrate (Dialysis) through filteration barrier membranes which are called Blood Renal Barrier. -46-

The Blood Renal Barriers - These are the membranes which separate the circualting blood inside : glomerular capillaries from the capsular space of the Bowman's capsule which contain the glomerular filtrate.

- The Filtration Barrier Membranes Are ·Formed Of The Following Structures : 1- The Fenestrated simple squamous cells of the glomerular blood capillaries.These fenestra (pores) are not covered by diaphragms, through these pores blood plasma and not blood cells can pass. 2- A non-fenestrated thick basal lamina (formed of fusion of the 2 basement membranes of podocytes and of blood capillaries). 3- The pedicles (implanted feet) of podocytes with filtration slits between them which are closed by slit diaphragms. The Afferent Arteriole Of Malpighian Renal Corpuscle has a thick wall, thick media, thick elastic lamina with juxta glomerular cells in its media. The Efferent Arteriole Of Malpighian Corpuscle has a thin wall, thin media, thin elastic lamina but with no juxta glomerular cells in its wall

Juxta Glomerular Complex (Apparatus) - It is a complex structure present at the vascular P?le of M~lpighian renal corpuscle. It regualtes blood pressure and electrolyte balance. - It is Formed of: Macula Densa, Lacis Cells and Juxta glomerular cells. 1- Macula Densa: It is the part of the distal convoluted tubule which is in contact with the vascular pole of a Malpighian renal corpuscle. - The cells of the distal convoluted tubule at macula densa are columnar with basal oval nuclei, they rest on no basement membrane. Macula densa act as osmo-receptor cells for any decrease in sodium ion concentration. 2- Lacis Cells : They are cubical cells with pale nuclei. They are

-47-

present between the afferent and eft'erent arterioles and the macula densa. Their structu re and Lmctions are similar to mesangial cells . 3- Juxta Glomerular Cells: They are epithelioid cells present in the media of the afferent arteriole. They have rounded nuclei and basophilic granular cytoplasm . These cells are in direct contact with lacis cells and with the cells of macula densa. These cells act as mechano receptors. They are stimulated in low blood pressure, they secrete Renin Hormone.

Functions Of Juxta Glomerular Complex 1- It secretes Hormone stimulates

Renin

lif~lf~!'

Juxtaglomerular T-V~t.i Cells In Afferent Arteriole

which ~~~~~~;.;..~~ secretion

of aldosterone from suprarenal to regulate blood

pressure and

.-~~,llill!g~

electrolyte balance. 2-

It

also

Macula Uensa

secretes

Erythropoietin Factor which stimulates blood

Juxtaglomerular Complex

cell development from the bone marrow.

The Proximal Convoluted Tubule - Each one is about 15 mm in length and 60 microns in d iameter.

- It is lined with 4-8 simple cuboidal cells with basal rounded nuclei and acidophilic cytoplasm. - The luminal surface shows acidophilic brush border with long microvilli to increase the absorptive surface. - The basal part has acidophilic striations and is rich in mitochondria and basal infoldings. - The cell borders are not clear. - The cells rest on clear basement membrane.

-48 -

Functions Of Proximal Convoluted Tubules : 1- Reabsorption of water, NaCI , Ca and phosphate. 2- Reabsorption of g lucose, amino acids and plasma proteins. 3- Excretion of creatinine, iodin e and penicillin.

The Distal Convoluted Tubule -Each one is about 5 mm in length and 20 microns in diameter. -It is lined with 6-10 simp le· cuboidal cells with central rounded nuclei and pale acidophilic cytoplasm. - The luminal surface shows less acidophilic brush border due to presence of few short microvilli. - They have relatively wide lumens. - Their basal parts has

acidophilic

mitochondrial

Tubule

striat ion and clear basal infoldings.

Distal

- The cell borders

Con volu tl•d Tubule

are not clear. - The cells rest on clear

basement

membrane.

('on voluted Tuhuks Of Kidne~·

Functions Of Distal Convoluted Tubules : I - Reabsorption of water and Sodium 2- Excretion of sodium, potassium and ammonium.

3- The Macula Densa Cells of the distal convoluted tubule act as receptors to control sodium ion level.

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The Loop Of Henle - It is a U-shaped tube which connects the proxima l with the distal convolut ed tubules of each nephron.

- It is formed of the following 4 parts: 1- Thick Descending Part lined with simp le cuboidel cells.

Thick Loop Of Henle

2- Thin Descending Part lined with simp le sq uamous cells . 3- Thin Ascending Part lined with simple squamou s cells 4- Thick Ascending Part

Thin Loop Of Henle . Collectin g Tub uI c

-i'lllrrl-

I ntcrstitia l

lined with simple cuboidal cells:

Cell

Functions of Henl's Loop: Parts Of Hcnl's Loop Through the _counter current mechani sm, the loop of Henle produce hyper~onic urine.

The Collecting Tubules -They are lined with simple cuboidal or simple columna r cells. -The cell cytoplas m is pale acidophi lic. - The nucle i are dark and central. -The lumen of each tubule is wide. - The cells have clear borders. - There is no lateral infolding s between the cells. -There is no microvilli on their surfaces. - There is no basal infoldings in the cells.

Functions: The collectin g tubules conduct and concentr ate unne through reabsorp tion of water and secretion of potassium . -50-

Function Of Kidneys 1- They filter the blood plasma to remove waste products. 2- They reabsorp useful substances. 3- Regualte acid-base balance of the blood. 4- Co~trol water and electrolyte balance of body fluids. 5- Excretion of uric acid, urea and creatinine. 6- They Have also The Following Endocrine Fucntions : a- Secretion of Renin I:Iormone to increase blood pressure. b- Secretion of Mcdullipin Hormone from endocrine cells in the renal medulla to decrease blood pressure. · c. Secretion of Erythropoietin Hormone to stimulate development of blood cells from bone marrow.

Blood Supply Of Nephron - The renal artery divides into 3 main branches. -Each branch divides into inter-lobar arteries. -Each inter-lobar artery gives rise to 2 arcuate arteries. - The arcuate arteries give inter-lobular arteries - The inter - lobular arteries give the afferent arterioles which form the glomerular capillaries, then arise as efferent arterioles. - Efferent arterioles which carry filtered blood, branch into capillaries around proximal and distal convolute4 tubules. These capillaries are called Peri-tubular Capillaries. -The medulla of kidney is supplied by Arterial Vasa Recta Vessels.

The Venous 'Drainage From The Nephron :

.

- The peritubular venous capillaries surrounding the proximal and distal tubules are collected to form The Inter-lobular Veins• .-The inter-lobular veins drain into Arcuate Veins. - The arcuate veins drain into Inter-lobar Veins. -The inter-lobar veins drajn into Renal Vein. - The renal vein drain into inferior vena cava. -51-

The Ureter The wall of ureter consists of these Layers : Transition al 1- Mucosa: epithelium resting on C.T. conum. 2- Musculosa: Smooth muscles arranged in the mner as 2/3 upper outer longitudin al and circular. In the Lower 113 of ureter the smooth muscles are arranged as inner longitudin al, middle circular and an outer Longitudinal Adventitia:lt is formed of elastic C.T. rich in B.V. nerves and lymphatic s.

.t. Corium

· Adventitia

·Ureter

The Urinary Bladder Its wall is formed of the following layers: 1- Mucosa: Transition al epithelium resting on a corium of C.T. 2- Musculosa: Formed of smooth muscles called its Detrusor Muscle, fibres run in different directions . The· internal sphincter is formed of circular smooth muscle fibres around. the neck of urinary bladder. 3- Adventitia: · Formed of fibro-elast ic C.T.

lirinary Bladder -52-

The Male Genital System The Male Reproductive System Consists Of: 1- Two Testes which produce spermatozoa and testosterone. 2- Excretory Ducts: They store, conduct and secrete nourishment fluid for spermatozoa. 3- Accessory male sexual glands which secrete nourishment secretion for spermatozoa as seminal vesicle, prostate and urethral glands. 4- A Copulatory Organ which is the penis.

The Testes - Each testis is a compound tubular mixed gland formed of exocrine seminiferous tubules which form spermatozoa and endocrine Leydig's Cells which secrete testosterone. The testis is formed of C.T. Stroma and Parenchyma.

The C. T. Stroma Of Testis Is Formed Of: 1- The Capsule Is Composed Of3 Tunicae: a- Tunica Vaginalis: Its parietal and visceral layers are lined with simple squamous mesothelium. b- Tunica Albuginea is formed of white collagenous C.T. It is thickened posteriorly to form The Mediastinum Testis. c. Tunica Vasculosa is formed of vascular C.T. 2- C.T. Septa of Testis arise from the mediastinum, they .divide the testis into compartments or lobules. From 2-4 seminiferous tubules are present in each lobule. 3- Reticular C.T. Network is present in the background of testes.

The parenchyma Of Testis Is Formed , Of Seminiferous Tubules and Leydig's Cells.

The Seminiferous Tubules - Each tubule has a· clear basement membrane covered externally with C.T. rich in fibroblasts and smooth muscle-like cells called Myo'id Cells.

-53-

-Each tubule is lined with spermato genic cells and Sertoli Cells.

Spermatogenic Cells and Spermatogenesis The Spermatogenic Cells Are The Following 1- Spermatogonia: They are primitive rounded cells with rounded nuc lei. Each one has 46 chromosom es. There Are 3 Subtypes of Spermato gonia which are the following: Dark A a- Type They Spermato gonia: Seminiferous chromatin dark have Tubules to divide material. They give ~ctive type A pale spermatog onia. Pale A b- Type They Spermato gonia: chromatin pale have material. They divtcle to give another type A pale types and also can gtve B. type to nse Spermatog onia In Testis S. T. c-Typ B Spermatogonia: They are large cells with large nuclei. They divide by mitosis to give rise to Primary Spermatoc ytes. 2- Primary Spermato cytes - They are the largest cells in seminifero us tubu les . - They have dark nuclei with clark chromatin . - Each cell contains 46 chromosom es. - They appear only after puberty (unlike primary oocyte in females which appear before puberty). - These cells undergo reduction meiotic cell division in order to give rise to Secondar y Spermato cytes.

-54-

3- Secondary Spermatocytes -They are small cells with rounded nuclei. -Each cell has 23 chromosom es. - Each cell quickly undergoes a second meiotic cell division (mitosis withous duplication

of

DNA) to g1ve

Secondary Spermatocytes

rise to 2

spermatids.

Primary Spermatocytes

4- Spermati ds: - They are the smallest

ce ll s yoid CeU

in seminifero us tubules .

Seminiferous Tubule

-They are present near to Sertoli cells. -Their nuclei contain dark chromatin . - Each cell has 23 chromosom es. - These cells can not divide but morpholog ical changes occur in each cell to be changed into spermatoz oon by a process called

Spermiogenesis. N.B. Spermatog enic cells are attached together by intercellul ar bridges which allow cytoplasm ic continuity between these cells.

-55-

Sertoli Cells are. elongated simple columnar cells present on the basement - They . membrane of the seminiferous tubules between the spermatogenic cells. -They have pale basal oval nuclei. - They have pale acidphilic cytoplasm. - Their cell membranes contain pockets in which spermatogenic cells are present. - Their cytoplasm contain many mitochondria, smooth endoplasmic reticulum, many lipid droplets, many lysosomes and many crystalloid inclusions. - The lateral borders of Sertoli cells are bound together with tight junctions. These junctions form a belt-shaped zone which divide the · '· seminiferous tubules into an inner or luminal and an outer or basal compartments. This belt shaped zone act as blood testes barriers.

Functions of Sertoli Cells : 1- They S(;Crete Androgen Binding Protein Hormone which promotes the functlons of testosterone hormone . 2- They secrete Inhibin Hormone to inhibit F.S.H. secretion. 3-:- They secrete a testicular fluid needed for spermatogenesis processes and transportation of developing sperms towards the lumen. 4- They secrete small amounts of Oestrogen. 5- They translocate developing spermatogenic cells towards the lumen of seminiferous tubules. 6- They phagocytose and eleminate degenerating germ cells and residual bodies (Zakaria, 1974). 7- Sertoli Cells join each other by different types of junctions to form the Blood-Testis Barrier.

-56-

The Blood-Testis Barrier - It is formed by a belt of junctional complexes present between the lateral borders of Sertoli Cells. -This belt-shaped Zone divides each seminiferous tubule into: .a- Basal Compartment which contains spermatogonia. b- Inner or Luminal Compartment which contains primary and secondary spermatocytes, spermatids and spermatozoa.

Function Of Blood-Testis Barrier - It selects nutrients, hormones minerals needed for growth and differentiation of spermatocytes to pass. througA. this barrier. - It protects developing spermatocytes from foreign blood antigens. - It protects developing spermatocytes from auto-immune-response.

Spermiogenesis - It is the process through which spermatid cells change into- mature spermatozoa without any cell division.

The Following Are The Steps Of Spermiogenesis 1- Formation Of Acrosomal Head Cap : Golgi Apparatus form an acrosomal vesicle which is rich in lysosomal enzymes and carbohydrates. This acrosomal vesicle moves · to be attached to the nucleus of spermatid cell to form an acro~omal cap.

2- Formation Of a Flagellum (Tail of spermatozoon): The pair of centrioles migrate towards the nucleus. One of these centrioles elongates to form a flagellum which is similar to a· ci),ium.

3- Migration Of Mitochondria : ·

·

Mitochondria migrate towards the flagellum to form a sheath around the flagellum.

4- For~ation Of The Head Of a Spermatozoon : The nucleus of spermatid elongates to form the hea,d of the sperm.

-57-

.

5- Cytoplasmic Changes Of Spermatids : The cytoplasm form a covering thin layer around each spermatozoon. The rest of non utilized cytoplasm is phagocytosed by Sertoli Cells.

The Structure Of A Mature Human Spermatozoon Each Spermatozoon is formed of head, neck , body and tail.

1- The Head Of A Spermatozoon is formed of condensed ·elongated nucleus and an acrosomal cap rich in lysosomal enzymes.

2- The Neck is a constriction behind the head. It contains two centrioles.

3- The Body or Middle Piece of a spermatozoon, from outside inward is formed of: plasma membrane, mitochondrial sheath, microfilaments and microtubules.

4- Tlie Tail is about 50 microns in length. It Consists Of: a-. The Principle Piece is long, formed of 20 microtubules and is •,

·covered by a fibrous sheath. b- The End Piece is very short, formed of 2 microtubules surrounded by a thin layer of cytoplasm.

The Seminal Fluid - It is the fluid which is ejaculated at the end of intercourse. - Its normal volume is from 2 to 4 ml. - Its reaction is alkaline. -Its normal count is 100 million spermatozoa per ml. of semen. - Normally up to 20% sperms have abnormal shapes.

The Interstitial Cells Of Leydig - These are the endocrine cells which secrete testosterone. -They are present in the C.T. present between seminiferous tubules. - They have acidophilic cytoplasm due to many fat droplets.

-58-

-They have many smooth endoplasmic reticulum, mitochondria, lipid droplets, crystalloids and well -developed Golgi. - The cells are present in groups and are surrounded with fenestrated blood capi llaries. N.B. The C.T. between sem iniferous tubules contain Endocrine Leydig's cells , C.T. fibroblasts, mast ce lls , macrophages , mesenchymal cells and Myoid Cells which are smooth muscle ce lls.

The Male Genital Ducts 1- The Tubuli Recti are lined with tall co lumnar cells. 2- The Rete Testis are lined with simple columnar cells. 3- The Vasa Efferentia are lined with simple co lumnar partially ciliated. 4- The Epididymis is about 6 m~ters in length . It is lined with pseudostratified columnar ciliated. The cilia are non motile and are considered as microvilli . The waH of epididymis is formed of circular smooth mqscles.

Function Of Epididymis 1- Absorption of certain testicular fluid. 2- Secretion of special protein needed for sperm maturation. 3- Phagocytosis of Columnar residual bodies. Ciliated 4- Storage of Epithelium spermatozoa. 5- Discharge sperms to Spermatozoa vas deferen s during ejaculation .. 6- It is the site of Epididymis maturation of sperms. N.B. Capacitation is the maturation changes in sperms in order to attain full capacity for fertilization.

-59-

5- The Vas Deferens: Its lower part is lined with pseudo-stratified columnar ciliated, but the cilia are non motile, they are microvilli. Its upper part is lined with pseudo-stratified columnar non-ciliated.

Pseudo Stratified Columnar Ciliated

The Musculosa Of Vas Deferens is formed of

Epithelium

inner longitudinal, middle circular and an outer longitudinal smooth muscles.

6- The Ejaculatory Ducts are lined with simple columnar or with pseudo-stratified co lumnar epithelium. There is no muscles in its wall.

Vas Deferens

7- The Spermatic Cord Is Formed Of:

1- Vas Deferens. Pampiniform Plexus of Veins. 3- Testicular artery and vem. 4·· Nerve Fibres 5- Cremastric Striated involuntary skeletal muscle. 2-

The Seminal Vesicle is lined with alternating simple columnar and cubical cells. Its wall is formed of inner circualr.and outer longitudinal smooth muscles. It secretes alkaline secretion rich in prostaglandine, fructose and protein for nutrition and motility of spermatozoa. -60-

The Prostate - ft is a single compound tubulo-acinar gland. - It encircles the neck of urinary bladder. - It is formed of C.T. Stroma and Parenchyma of ce ll s.

Prostatic Concretion

Prostatic Acini ·

The C.T. Stroma of Prostatic Gland Consists Of : The Capsule is formed of

Pseudo Stratified Columnar Epithelium

C.T. and smooth muscles.

The Trabeculae are formed of C.T. and smooth muscles. The Reticular Network is formed of reticualr cells and

Prostate Gland The Parenchyma Of Prostatic Gland : fibres.

- The Prostatic Acini are lined by secretory epithelium of cuboidal, co lumnar or pseudostratified co lumn ar. The lining epithelium depends on the activity of the gland. - According to the postition of acini in relation to the central urethra the prostatic acini are distributed as follows: 1- Mucosal Acini: They are close to the male urethra, they are small acini but they may enlarge in old age to form prostatic adenoma. 2- Submucosal Acini: They SLtrround the mucosal acini . They are intermediate in size but their size enlarge in old age (Senile prostate). 3- Main Prostatic Acini: They are present in the peripheral part of the prostate. They are large acini with long ducts. Enlargement of these acini occur in cancer prostate. Functions Of Prostate: It secretes milky fluid rich in proteolytic and acid phosphatase enzymes. Prostatic Concretions are calcified bodies of glycoprotein prostatic secretion. They are present in the prostatic acini in old age.

-61-

Bulbo Urethral Gland Of Cowper: - They are 2 small glands present around the membrano us urethra Each gland is covered with thin C.T. capsule. - Each gland is formed of

/

2 Corpora Cavernosa

tubulo acinar secretory

Corpus Spongiosum

units. - The acini are lined with simple

cuboidal

or

T. SIn Penis

simple columnar cel1s.

-They secrete viscous mucus secretion directly in the urethra

The Penis - It is the copulatory organ in males.

-It is formed of a root and a body

- The Root of Penis is covered with skeletal muscles. It consists of bulb of penis and 2 crura

-The Body of Penis Consists of 3 Corpora: 2 Corpora cavernosa and a corpus spongiosu m . -The 3 corpora are surrounde d with C.T. and thin skin. · The skin is pigmented with no subcutaneo us fat.

-62-

- The erectile tissue of the 3 corpora is formed of blood spaces lined by endothelium and are separated by trabeculae of ·smooth musles, · collagenous and elastic fibres. - The 2 corpora cavemosa fuse together on the dorsum of penis. -The corpus spongiosum contain the male urethra. It terminates by the glans penis. - Glans penis is covered with a· skin fold called prepuce which is remvoed by circumcision. - Erection of penis is a parasympathetic response during which the blood spaces of the corpora are engorged with blood.

· Ejaculation of semen is a sympathetic response.

The Male urethra -It is about 15 to 20 em in length.

- It Consists Of The Following Three Regions : 1- Prostatic Part Of Male Urethra: - It is the first part that traverse the prostate. - It is short and V-shaped in cross section. -Ejaculato ry and Prostatic ducts open into it. - It is lined with Transition al Epithelium . - It .is surrounded with inner longitudinal and outer circular smooth ' . muscles which form the internal sphincter of the urinary bladder.

2- Membra nous Part Of Male Urethra : - It is very short about 1 em in length. - It is lined with pseudostratified columnar epithelium.

-Vascular C.T. and smooth muscles are present under the epithelium. - It is surrounded by voluntary striated muscles which form the external sphincter of the urinary bladder - Ducts of bulbo-urethral glands open in membranous urethra.

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3- Penile or Bulbous ~nd Pendulous Parts Of Urethra : - It is the longest part of male urethra. -It is present in the corpus spongiosum of penis .

- The Bulbous Part is the proximal dilatation. of urethra. It is lined with stratified columnar epithelium/ -.The pendulous Part is the distal dilatation of the urethra at the fossa navicularis. It is lined with stratified squamous epithelium.

Glands Related To Male Urethra : 1- Prostatic Gland open in the prostatic urethra. 2- Intra-epithelial Littre Glands open in penile urethra. 3- Extra-epithelial Littre Glands open in penile urethra. 4- Bulbo-urethral Glands open in bulbous part of urethra.

The Female Urethra - It is· about 4-5 em in length. - It conducts urine only from bladder to outside. - It is lined from inside outwards by transitional, pseudostratified

columnar, then stratified squamous at its external opening. - Its middle part is surrounded with striated voluntary muscles which act as external voluntary sphincter.

-64-

The Female Genital System The Femal e Reprod uctive System Consis ts Of : 2 ovaries (Gonads), 2 Fallopian Tubes, One Uterus, One Vagina,· 2 Mammary Glands and The External Genitalia.

The Ovaries - Each ovary is an almond shaped organ, measuring 4x2 em. - Each ovary is covered by simple cuboid al cells. - Under the epithelium, there is a layer of white collagenous C.T. called Tunica Albuginea. - Each ovary is formed of an outer Cortex and an inner Medull a. - The Cortex of each ovary contain s: Ovarian Follicles, spindle-shaped Cells and C.T. Fibres. - The Medul la of the ovary contain s : Vascular C.T. rich in tortuous blood vessels, C.T. Fibres, Lymphatics, Nerves and Smooth muscle fibres.

The Ovari an Follicles 1- Primo rdial Follicl es - They are present in childhood ovaries (From birth till puberty). - Their number is about 200.000 in each ovary. - Each Follicle is formed of Primar y Oocyte and Follicular Epithelium -.The Prima ry Oocyte : - It is a rounded cell- about 40 mjcrons in diameter. . - It· has a pale cytoplasm rich in mitochondria, free ribosomes, few endoplasmic reticulum and small Golgi apparatus. - Its nucleus is large with large nucleolus - It contains 46 chromosomes. It is present in a prolonged prophase stage until .puberty. It completes its division with each menstrual cycle just before ovulation.

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- The Follicular Epithelium: It surrounds the oocyte, it is formed of granulosa cells resting on a clear basement membrane . - At puberty, The Follicular Stimulatin g Hormone (FSH) of the pituitary gland stimulates primordial follicles to grow and to be changed into Primary Follicles .

2- Primary Ovarian Follicles F.S.H induce these developme ntal changes in primordial follicles m order to be changed into Primary Follicles:

The Primary Oocyte increase in size to about 50 microns. - Its

cyto plasm

Follicles

is clear with

prominent Golgi apparatus.

- It has many mitochond ria, free ribosomes and smooth

Primary Follicle

endoplasm ic reticulum. - The surface of oocyte is covered with Zona pellucida and short

.;:;...::..-.~r

Primary (!•Jcyte

microvilli.

The Follicula r Cells proliferate and

form

Granulosa

Cells

Section In Ovary

around the oocyte .

The Stromal Cells around primary follicles start to differentia te into Theca Folliculi Layers Further developme nt of primary follicles under the effect of FSH and oestrogen change primary follicles into Secondary Growing Follicles.

3- Seconda ry Growing Follicles -It has a large oocyte covered by thick acidophilic Zona Pellucida. - Long microvilli project from the zona pellucida. - Granulosa cells around oocyte proliferate to form 8-12 layers.

-66-

- Few cavities filled with Liquor Folliculi appear between granufosa cells.

- The Stromal Cells around growing follicles differentiate into: a- Theca Externa formed of C.T, fusiform cells and

Theca lnterna

blood capi !!aries.

b- Theca Interna formed of secretory theca cells which secrete oestrogen,

Cells

.. ~~!"~~~'G..Ul androgen and nutritive Developing Secondary Ovarian Follicle substances.

4- Mature Graafian Follicles

\....,~~;rheca

maturation the m follicles - Maturity follicles takes l 0-14 clays. - Each follicle

Interna

..co...;._., Granulosa Cells -~~~..._

Follicular Anterum Oocyte

nucleus. The

oocyte

surrounded Zona Pellucia, Proligerus).

by Corona Radiata

-67-

.and Cumulus Oophorus (Discus

- In this follicles, meiosis is completed in primary oocyte to produce secondary oocyte which is a large rounded cell with 23 chromosomes. - The Antrum is the large cavity of the Graafian follicle. It is filled with follicular fluid. It is lined by many layers of granulosa cells that rest on a clear basement membrane. - The Graafian Follicle is sun·ounded by Theca l~'olliculi which is formed of: 1- Theca Externa formed of C.T., fusiform cells and B.V. 2- Theca Interna formed of theca cells which secrete Oestrogen, androgen and nutritive substances.

Oogenesis or Ovogenesis It is the developmental changes in oogonia in order to be transformed into mature ova. Oogenesis occur through the following stages :

1- Proliferation of primordial germ cells to give many oogonia. 2- Growth of oogonia to be changed into primary oocytes. Each oocyte contains 46 chromosomes. 3- Maturation of oocyte oocurs just before ovulation in which the first meiotic cell division is completed giving rise to the following: a- One Secondary Oocyte (with 23 chromosomes). b- A First Polar Body (which will degenerate). 4- Ovulation is the rupture of a mature Graafian follicle and the release of an oocyte. It is controlled by Oestrogen hormone and Luteinizing hormone (LH). Fertilization is the process of penetration of a sperm to secondary oocyte to give a fertilized ovum. After fertilization the second meiotic cell division is completed.

Fate Of Mature Graafian Follicle At the mid menstrual cycle, the mature Graafian follicle is ruptured (ovulation) giving rise to secondary oocyte and a collapsed body in the ovary called Corpus Luteum. -68-

The Corpus Luteum - It is a temporary endocrine yellowish body present in the ovary after mature the of rupture Graafian follicle. - [t is formed and maintained under the effect of Luteinizing Hormone (LH) sec reted from H~~~q. Granulosa pituitary gland. - It is formed of the follo\ving Lutein

2 Layers Of Cells :

Cells

a- Granulosa Lutein Cells which are large .pale ce lls rich e ndoplasmic m smooth reticulum , mitoch ondria and lysosomes. They are cove red with long microvilli. They

~~~~~~~~ ~

sec rete Progesterone

b- Theca Lutein Cells which are small darkly - stained polygonal cells. They are rich in smooth endoplasmic reticulum, mitocohondria andlysosomes. They have no microvilli. They secrete oestrogen.

Types and Fate of Corpora Lutea 1- Corpus Luteum Of Menstruation : ft is a yellow body which live only for 10-14 days if pregnancy does not occur. [t then degenerates to be transformed into -corpu s albicans (white body).

2- Corpus Luteum Of Pregnancy: If fertilization occurs, the corpus luteum enlarges and persists functioning for 3 months . It secretes oestrogen, progesterone and relaxin hormones. After this period it changes into Corpus Albicans .

3- Corpus Albicans: It is a white degenrated sac formed of dense C.T.

-69-

4- Corpus Haemorrhagicum: It is the corpus luteum which occur in certain animals . It has central haemorrhage . Atretic Ovarian Follicles are the degenerated non-develop ed ovarian follicles.

Interstitial Hilus Cells of the ovary are polygonal cells present between ovarian follicles. They secrete androgen which is then transformed into oestrogen by aromatase enzyme.

Uterine Fallopian Tubes or Oviducts - These are 2 muscular tubes, each is about 12 em. - Each fallopian tube is divided anatomically into 4 parts:

1- Intramural Part which is embedded in the uterus.

2- Isthmus Part is a anarrow segment close to the uterus. 3- The Ampulla is the widest and middle segment. 4- The Infundibulum is the distal funnel-shaped segment.

C.t Corium

Uterine Fallopian Tube The wall of Fallopian tube is formed of: 1-Mucosa is highly folded lined with 4 types of cells: a- Simple Colunmar Ciliated Cells. b- Simple Columnar Secretory Cells. c- Peg Cells which are exhausted secretory cells. d- Stem Cells for renewal of columnar cells . 2- Lamina propria formed of loose C.T. 3- Muscular Layer: Inner circular and outer longitudinal smooth muscles.

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4- Serosa formed of C.T. covered by simple squamous mesothe lium.

Functions Of Fallopian Tubes: (1) It receives the oocyte from the In

(2)

ovary.

its , Simple Columnar

ferti lization

ampu lla

occurs. (3) Its secretion

~_,~~~~~ Uterine

nourishes sperms and

transport sperms ova. (5)

Its

Glands

cilia

( 4)fts

ova.

and

muscles

.\nd Basal

transport zygote to the uterine cavity. (6) mucosa cyclic

LayersOf

Its

~).~,_,J;ao: Endomctrium

undergoes changes

with

each menstrual cycle .

Uterus

The Uterus - It is a single organ present between urinary bladder and rectum. - It is formed of body, fundus and cervix.

-Its wall is formed of: Endometrium , Myometrium and Perimetrium.

1- The Endometrium Is Formed Of: - Simple Columnar ciliated cells alternating with simple columnar non-ciliated secretory cells .

- Uterine Glands which are simple or branched tubular - C.T. Corium between the uterine glands rich in leucocytes, macrophages, mesenchymal stromal decidual cells, coiled and straight arteries and veins .

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- Hormonal changes occur in the endometrium with each menstrual cycle, therefore it is divided into the following layers : a- I•'unctional Superficial Layer which undergoes cyclic shedding with each menstrual cycle. It is supplied with coiled arteries. b- Basal Deep Layer formed by the basal parts of uterine glands. The epithelial lining of these glands undergoes cyclic division with each menstrual cycle to cover the row surface endometrial areas. This layer is supplied with straight arteries.

2- The Myometrium Of Uterus Is Formed Of: a- Submucosal Layer present under the endometrium. It is formed of longitudinal smooth muscles enclosing between them B.V. b- Vascular Layer: It is the middle circular and oblique smooth muscles with many arcuate arteries between the muscles. c- Supravascualr Layer: It is the outermost longitudinal smooth muscle layer.

3- The Perimetrium is formed of simple squamous mesothelium and C.T.

The Cervix Of Uterus is formed of dense C.T., Tubulo-acinar glands and smooth muscles. The cervix is covered by the following epithelium:

a- The internal os and cervical canal are lined with simple columnat ciliated alternating with simple columnar non-ciliated which secrete mucus. b- The external os is covered with non-keratinized stratified squamous epithelium.

The Menstrual uterine Cycle It is the cyclic endometrial changes which is controlled by pituitary and ovarian hormones (FSH, LH., Oestrogen and Progesterone)

- Normaly the duration is about 28 days.

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-The first menstrual cycle (Menarche) appears at 12-15 years. - According to the endometrial changes the cycle is divided into: 1- The Menstrual or Destructive Phase: It is about 3-5 days. The functional endometrial layer undergoes necrosis. It will give rise to a discharge of menstrual fluid formed of unclotted blood, epithelial cells, C.T. cells and uterine gland secretion.

2- Proliferative or Follicular or Estrogenic Phase : -This phase occurs between the 5th to the 14th day of the cycle. - This phase is controlled by FSH and oestrogen hormones . - Proliferation of the lining uterine eptihelial cells, C.T. stromal cells and endometrial glands occur to cover the row surface areas of the endometrium .

3- The Secretory or Luteal Phase: -It occurs between the 15th to 27 th clay of the cycle. ~ It is controlled by L.H (Luteinizing Hormone) and progesterone - The uterine gland become elongated, coiled, tortuous, filled with glycogen and mucus. -The C.T. stroma is oeclematous and is rich in spiral arteries. 4- Ischemic Phase: It occurs at the 28th day of the cycle. Corpus luteum degenerates if there is no pregnancy therefore progesterone level is dropped. Constriction of uterine arteries results in ischemia and degeneration of the functional layer of the endometrium

The Placenta - It is a temporary organ which transfers nutrients and oxygen to the

embryo. It also secretes hormones . - It is formed of a foetal part (Chorion Fronclosum) and maternal part (Decidua Basalis) The Foetal Part of placenta is formed of free and anchored chorionic foetal villi which are covered by cytotrophoblast and -73-

syncytotroph ob last. In the centre of each vi llu s there is loose C.T., foetal blood capil laries, and large macrophage celis called Hofbauer's

Cells. The Maternal Part of Placenta is formed of the Decidua Basalis The Decidua Basalis: It is the endometrial' part wh ich is in contact with

the embryo. It contains many decidual ce ll s which are

multinucleated polygonal cells . It also contain s stromal C.T. ce ll s, blood leucocytes and uterine arterioles and ven ules.

Blood Placental Barrier: These are the layers of cells and tissues that separate the foetal

blood

from

the

maternal blood. It is formed

of the following tissues: 1-

Simple endothelium

squamous of

foeta l

blood vesse ls. 2- Basement membrane of the previous endothelium 3- Foetal C.T. core of the choron ic villi 4- Basement membrane of cytotroph oblast 5- Cytotrophoblast cubical ce ll s with clear cell boundaries. 6- Syncytiotrophoblast cells with non-clear cell boundaries. 7- A Fibrinoid Coat which is formed of dense hyaline material. It prevents most of the immunological reactions.

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Functions Of Blood Placental Barrier 1- It allows the passage of 02 ' cob hormon es and antibod ies 2- It prevents the passage of toxic chemic als, drugs and antigens. 3- The fibrinoi d placent al coat preven ts immuno logical reaction s.

Functions Of Placenta l- Respiratory function: It supplie s 0 2 to foetus and remove C0 2 2- Nutriti ve Functio n: It supplie s the foetu s with nutrient s . 3- Excretory Functio n: It remove s waste product s from foetal circulat ion. 4- Protect ive Functio n: It prevent s the passage of harmful materials. 5- Storage function: It stores iron, ca lcium, proteins and carbohy drates. 6- Hormo nal Secretion: It secretes the followi ng hormon es: a- Human Chorion ic Gonado tropin (HCG). b- Human Chrioni c Somato mammo trophin (HCS). c- Oestrog en, Progest erone and relaxin hormon es .

The Vagina - ft is a muscul ar tube ,..........,~-....~-..... atified which extend from the cervix of uterus to the externa l genitalia. - Its wall is formed of: Mucosa , Muscul osa and Advent itia. The Mucosa is lined _ with non-ker atinized _ _ _ --- -stratifie d squamo us : ~- -- :-_-_ epitheli um rich 111 - .=-- ~-: - ~;~~;~ ~"" glycoge n. The C.T. Corium is rich in blood capillar ies, elastic and collage nous fibres, But there is no glands. The Muscu losa is formed of smooth muscles arrange d as inner circular and outer longitud inal. Circula r skeletal muscles are present at the lower end of vagina (They belong to levator ani muscle). .-;:,_~

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The Adventitia is formed of C.T. rich in blood vessels. Labia Majora are fo lds of hairy skin rich in adipose C.T. with few smooth muscles . Labia Minora are folds of vascula r erectile C.T. with sweat and sebaceo us glands. The vestibule is the area that receive s the opening s of vagina and urethra. It is covered with stratified squamo us epitheli um . The vestibule contains these glands: 1- Bartholin Glands are tubulo- acinar glands which secrete mucus. 2- Vestibular Glands are tubulo- acinar glands which secrete mucus.

The Mammary Glands - They are compou nd tubulo- acinar glands . - They are covered with skin very rich in adipose C.T. Mamma ry - Each gland is divided by Gland C.T. septa into 10-15 lobes. Before puberty, mamma ry glands are formed oflactif erous ducts. -At puberty the lactiferous ducts proliferate and increase in size and number . More adipose C.T. is Resting Mamm ary Gland accumu lated between its lobules. - The Ducts are lined with simple cuboida l or simple column ar cells. Myoepithelial cells are present in the wall of mamma ry gland ducts. - With each menstru al cycle few secretions appear in the mamma ry ducts, congest ion of mamma ry B.V. _and oedema of the C.T. occur. - The Nipple is a conical projection from the mamma ry gland. It consists of 15-20 lactiferous ducts.

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-The Arcola is the pigmented sk in which surrounds the nipple. -Montgom ery's Glands are modified sweat glands under the areola. - The non-lactating mammary glands are formed of many ducts se parated with C.T.

- During pregnancy oestrogen, progestero ne , growth hormone, prolactin, glucocorti coid and ins ulin hormones prepare the breast for lactation.

The Lactating Mammary Gland - It is covered with skin rich in subcutane ous fat. - Interlobar fibrous C.T. septa radiate from the nipple to divide the breast into 15-20 lobes and lobules. Acini or - Loose cellular C.T. is present in the backgroun d of lobes and lobules . The Parenchyma is formed of mammary acini Milk Rich In and ducts.

- The Mammary Acini by simple lined are simple or columnar are cells The . cells cuboidal mitochond ria, in rich 1ysosomes , secretory Lactating Mammary Gland droplets. granules and fat -The acini are surrounded by myoepithe lial cells. - The acini are filled with milk rich in fat , sugar and protein.

- The Mammary Ducts: Small ducts are lined with simple cuboidal cells and large ducts are lined with simple columnar cells. Myo-epithelial cells are present in the wall of mammary ducts. N.B. After labour the prolactin hormone stimulates milk secretion. Suckling_ of the nipple by the child stimulates ·secretion of oxytocin which results in contraction of myoepithe lial ceiis around alveoli and ducts, this allow the passage of milk towards the nipple.

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The Eye -The eyes are the organs of vision. - Each eye is formed of: 1- Outer Fibrous Layer: Cornea and Sclera. 2- Middle Vascular Layer: ftis , Ci li ary body and Choroid. 3- Nervous or Inner Ectodermal Layer: Retina. The Refractive Media Of The Eye are: The Cornea, The Aqueous Humour, The lens and The Vitreous Humour.

Choroid

Sclera Ciliary Body

Optic Nerve Optic Disc

Vitreous Body -

-Tr-

Lens

.. Jl- Anterior I

'

Fovea Centralis

I'

,!{! Chamber

, ~/""Posterior Chamber

Section In Eye Ball

The Cornea It is formed of the following 5 layers I- Epithelium non-keratiniz ed stratified squamous. -The basal cells are columnar with basal oval nuclei. - The middle cells are polygona l cells. -The superficial cells are squamous cells with microvilli. 2- Bowman's Membrane: It is a homogeneou s thick layer of collagenous fibrils . It acts as protective corneal barrier against trauma and bacterial invasion.

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3- C.T. layer or Substantia Propr1a: It is formed of regularly arranged collagenous fibrils, flat fibwb last ct> lls and homogeneous ground substances.

4-Descemet's Membrane: It is a homog cnf •us thick basement , membrane formed of collagenous fibrils and ground substance.

5- Endothelium: It is a single Stratified Squamous Epithelium

layer of simple squamous cells that lines the anterior chamber of the eye ball.

The Cornea Is Transparent due to: a- It has no blood vessels in its --,-,.-..- Substantia Prpria

layers. b- It is kept wet with tears clay

Dcsccmet's. Membrane

and night. c- Continuous withdrawal

of

water from the cornea make it

. ., ...... .-

-.

..

/

_..__ Endothelium

Cornea

clear. d- The regular arrangement of the

covering epithelium and of the collagenous fibrils make the coma transparent. e- The refractive index of all corneal components is the same.

The Sclera - It is the white opaque C.T. coat of the eye. - Its opacity is due to presence of water and irregular C.T. fibrils. - It is formed of irregularly arranged collagenous fibrils with flat fibroblast cells and elastic fibres to resist muscular contraction. - The tendons of extra ocular muscles are attached to the sclera.

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- The sclera is pierced posteriorly by the optic nerve. - Its innermost layer or Lamina Fusca is rich in pigments. The Corn eo - Scleral Junction or Limbus The Limbus: It is a ring-like junction between comea and sclera. It is about 1 mm wide. it is very rich in blood capillaries. It contains The . Canal Of Schlemm which drains the aqueous humour from the anterior chamber of the eye to the venous drainage of the whole eye. Obstmction of this drainage gives rise to Glaucoma. The Following Changes Occur at the Corneo-Scleral Junction. 1- The stratified squamous epithelium of comea is continuous with that of conjunctiva. 2- Bowman's membrane of comea is replaced by C.T. of sclera. 3- The regular C.T. of comea is replaced by irregular C.T. of sclera. 4- Descemet's membrane splits to be changed into pectinate ligament. 5- Corneal endothelium becomes continuous with that of canal of Schlemm. · The Middle Vascular Coat Of The Eye is formed of the Iris, Ciliary body and Choroid.

The Iris - It is a contractile, pigmented vascular diaphragm of muscles. - It is present between anterior and posterior chambers of the eye. -The Pupil: It is the central adjustable opening of the iris. The Iris Is Formed Of The Following Structures: 1- Non- continuous layer of collagenous fibrils, fibroblasts and pigment cells covered by simple squamous cells. 2- Vascular pigmented C.T.layer. 3- Sphincter pupillae circularly arranged smooth muscles. They contract under parasympathetic stimulation to close the pupil. 4-Dilator pupillae muscle: They are myoepithelial cells that dilate the pupil with sympathetic stimulation. 5- Two layers of pigmented cuboidal cells.

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The colour of the eye depends on ·he amount and distribution of melanin _pigments in the iris. Blue eyes hc've few pigments. With increasing pigments the following colours 'lppear: grey, green, . brown and black. The eyes of albino havt no melanin pigments in their iris.

The Ciliary Body -It is a ring-shaped muscular organ rich in pigmented C.T. - It is formed of ciliary processes and ciliary muscles. - The Ciliary Processes are about 70 projections from the ciliary body. They are connected with the lens. They are covered with 2 layers of simple cuboidal secretory cells, they secrete the aqueous humor. - The Ciliary Muscles are 3 groups of smooth muscles. They are arranged as: outer meridian muscles, radial muscles, and circualr or sphincteric muscles. They are attached to the lens by suspensory ligaments. They are responsible for accomodation of vision for far and near objects.

The Choroid - It is a vascualr pigmented layer. It is present between the sclera extemaly and the retina intemaly. - It supports the retina and provides it with blood. - It absorbs light in order to prevent blurring of vision.

The Choroid consists of the following 5 layers: 1- ·Suprachoroidal Layer: Formed of C.T. rich in melanocytes, fibrocytes, macrophages, elastic fibres and C.T. matrix. 2- Vessel Layer: formed of tortuous B.V. embedded in pigmented C.T. 3- Capillary Layer: formed of fenestrated blood capillaries. 4- Bruch's Membrane is formed of fusion of 2 basement membranes of the fenestrated capillaries and that of the pigmented cell layer.

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5- Pigmented Cell Layer Of Choroid is formed of simple cuboidal cells rich in melanin pigments. They are joined together by tight cellular junctions to prevent diffusion of foreign substances from the choroid to the retina.

The Aqueous Humor Of The Eye. - It is a special fluid that fills anterior and posterior eye chambers . - It is secreted by the ciliary processes. -It is drained into canal of Schlemm then into the eye veins. - Obstruction to its drainage give rise to Glaucoma.

The Vitreous Humor or Vitreous Body Of The Eye. - It is a transparent gel-like mass filling the vitreous space which is the

space between the lens and retina. - It is formed of 99% water, hyaluronic acid, fine collagenous fibrils, . macrophages and hyalocyte stellate shaped cells. - It holds the lens in its place and prevents retinal detachment. The Refractive media Of The Eye Includes: Cornea, Aqueous Humor, Lens and Vitreous Humor.

The Lens - It is an elastic transparent biconvex structure.· - It is formed of modified epithelial ectodermal ce11s. - It is attached to the ciliary body by suspensory ligaments. - It is formed of lens fibres which are modified columnar cells. - The lens is covered with simple cuboidal cells at its anterior surface. - The lens has also simple columnar cells at its equators. - The lens is enveloped in an elastic capsule which is present outside the epithelium. In this capsule the suspensory ligaments are inserted.

Cataract: Normally the lens is transparent, if it becomes opaque it results in dimmed vision and the disease is called Cataract.

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The Retina - It arises from the inner layer of the optic cup.

- The retina proper is formed of 9 layers except at its fovea centralis, at the optic papillae and at the part of ora sen·ata of retina

- The Pigmented Cell Layer Of The Choroid - It consists of.simple cuboidal pigmented cells. - The cells are attached with each other by tight junctions.

-The cells are attached also to Bruch's membrane of choroid. - They have surface microvilli. - The cells have basal rounded nuclei. - Their cytoplasm is rich in melanin granules, mitochondria, endoplasmic reticulum, lysosomes and residual bodies

- Functions Of Pigmented Cell Layer: 1- Absorption of light. 2- Phagocytosis of old discs of rods. 3- Storage and release of vitamin A. 4- Their tight junctions form The Blood Retinal Barrier.

The 9 Proper Layers Of The Retina Are: 1- Rods and Cones Layer Of The Retina:

The Rod Cells - There is about 12.0 millions of rods in both retinae -They mediate vision in dim (dark) light - Each Rod is formed of: 1- Outer Segmen t formed of parallel discs rich m rhodopsin molecules which are renewed constantly. 2- Connect ing Stalk: It contains a modified cilium. 3- Inner Seg111ent: It contains mitochopqria, Golgi body, endoplasmic reticulum, ribosomes and microtubules. 4- Cell Body of each rod contians one rounded nucleus. -83-

The Cone Cells - They mediate vision in day light. - Human retina contains about 7 millions of cones. - Each cone is formed of: 1- Outer Segment: It is conical in shape with _parallel discs rich in iodopsin which respond to: day light and colour vision. Cone discs are not shed or phagocytosed by the pigmented cell layer. 2- Connecting Stalk: It contains a modified cilium. 3- Inner Segment: It contains mitochondria, Golgi body, endoplasmic reticulum, ribosomes and microtubules. 4- Cell Body of each cone contains one large pale nucleus . .2- The Outer Limiting Membrane Of The Retina: It is a junctional complexes between neuroglia cells. 3- The Outer Nuclear Layer Of The Retina: It consists of the cell bodies of rods and cones cells and their nuclei. 4- The Outer Plexiform Layer Of The Retina: It is a synaptic zone between axons of rods and cones cells (First order neuron) and the dendrites of bipolar nerve cells and horizontal cells. 5- The Inner Nuclear Layer Of The Retina: It consists of the nuclei of bipolar nerve cells (Second order neuron), nuclei of horizontal cells, nuclei of amacrine cells and Muller's cells. 6- The Inner Plexiform Layer Of The Retina: · It is a synaptic zone between axons of bipolar nerve cells and dendrites of ganglion nerve cells. 7- The Ganglion Nerve Cell Layer Of The Retina:· ·It contains the bodies of ganglion cells (Third order neuron). 8- The Nerve Fibre layer Of The Retina: It consists of the unmyelinated axons of ganglion cells which form the optic nerve. 9- The Inner Limiting'Me mbrane· Of The Retina: It is formed by the terminal processes of Muller cells. · -84-

The Choroid Pigmente d Cell Lavf'r

Outer Nuclear Layer Outer Limiting Membra ne Outer Plexiform Layer

- - Inner Plexiform Layer _.......,._ Ganglion Cell Layer ·-....!- - - - ------ -'"--- Inner Limiting Membra ne

The Retina

The Macula Lutca or Yellow Spot Of The Retina: It is the part of the retina which is directly opposite to the centre of the lens. It has more than one row of ganglion cells.

The Fovea Ccntrali s Of The Retina: -It is a central rounded depressio n in macula lutea - It has no blood vessels , no pigmente d cells and no rods. The Fovea

Centrali s is formed of the following layers only: a- Cones layer only. b- Outer Limiting membran e: c- Outer nuclear layer. - The fovea central is is the area of greatest visual acuity.

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The Optic Disc Of The Retina or Blind Spot: It is the site where optic nerve fibres converge to form the optic nerve. It has no photoreceptors. It is not sensitive to light. The central retinal artery and vein course through this optic disc.

The Ara Scrrata of The Retina: It is the anterior borders of the retina which contains only rods, cones and muller cells.

The Baniers Of Eye Against Harmful Elements Consists Of : 1- Presence of tight junctions between the pigmented cell layer. 2- Presence of tight junctions between the endothelial cells of the retinal

-~~M.tw Stratified

Columnar ~R-~~- Epithelium

blood capillaries.

With · Goblet Cells

3- Bruch's membrane of the choroid.

'

4- Aqueous humor and vitreous humor act also as barriers for the eye.

The

Conjunctiva

IS

a

mucous

Conjunctiva

membrane formed of: a- Bulbar Conjunctiva which covers the sclera. it is formed of non-keratinized stratified squamous epithelium and C.T.

b- Palpebral Conjunctiva which covers the inner surface of the eye lid. It is formed of stratified columnar epithelium which has surface

microvilli.

Connective

tissue · is

present

under

epithelium.

The conjunctiva has lubricant, protective defensive functions.

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the

The Ey_e Lids - They are skin folds that protect the eyes from injuries and excessive light. Each eye lid consists of: l- Thin skin with eye lashes at its free margin but with no subcutaneous fat. 2- Orbicularis occuli muscle, formed of skeletal voluntary muscles. 3- Tarsal Plate formed of dense collagenous C.T. 4- Meibomian Tarsal Glands which are modified sebaceous glands that secrete oily secretion which prevents sticking of eye lids together and delays evaporation of tears. 5- Palpebral Conjunctiva formed of C.T. covered with stratified columnar epithelium.

The Lacrimal Glands are compound tubulo-acina r glands. They are formed of pure serous acini which are lined with simple cuboidal cells. The acini are surrounded with myoepithelia l cells. They secrete tears which are rich in lysozymes. Tears pass to lacrimal puncti, then to lacrimal sac, then to lacrimftl duct. The lacrimal duct open in the nasal cavity.

Conjunctiva

Eyl·-la

kin

Eye Lid

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The Ear -The ear is the organ of hearing and equilibrium. - It is formed of External, Middle and Internal Ears.

The External Ear Is Formed Of: 1- The Ear Pinna or Auricle: It is formed of elastic cartilage covered with skin. It collects sound waves towards the drum. 2- The External Auditory Meatus: It is formed of elastic cartilage and bone. It is covered with skin. Under the skin there are Ceruminous glands which secrete cerumin (Wax). There is also sweat and sebaceous glands. All these have protective functions. 3- The Tympanic Membrane: It separates the external ear from the middle ear. It is formed of:. a- Stratified squamous epithelium. b- Dense C.T. formed of radial and circular fibres. c- Simple cuboidal epithelium facing the middle ear.

The Middle Ear or Tympanic Cavity It is lined with simple cuboidal epithelium. -The tympanic membrane (drum) is present in its lateral wall. - It is separated from the internal ear by the oval and the rounded windows. - It is communicated with the nasopharynx by The Eustachian Tube which is lined with simple columnar ciliated near the middle ear and with pseudostratified columnar ciliated near the pharynx. It equalizes the air pressure of the middle ear. - The middle ear contains: 3 bony Ossicles, 2 Muscles, and the Chorda Tympani Nerve which is a branch of the facial nerve. - .The 3 Bony Ossicles are: Malleus, Incus and Stapes which articulate together by synovial joints.

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.•:..

The Malleus is attached to the tympanic membrane and the stapes is attached to the oval window. - The 2 Striated Muscles are: Tensor tympani and Stapedius muscles, they protect the ear from loud noises.

Internal Ear or Labyrinth - It consists of bony labyrinth and membranous labyrinth. - The membranous labyrinth is a closed system of membranous ducts and sacs within the bony labyrinth. - The space between bony and membranous labyrinths is filled with

Perilymph. - The ducts and sacs of membranous labyrinth are filled with Endolymph (rich in Na+ and K+). - The internal ear has 2 sensory o!·gans, each organ has a bony and a membranous labyrinth. - The sensory organs are: Vestibular apparatus for equilibrium and Auditory apparatus for hearing

The Auditory Apparatus - It is formed of bony labyrinth .which is the cochlea and membranous labyrinth which is formed of the following three cavities: scala media, scala vestibuli and scala tympani. - The Cochlea consists of a central pillar called modiolus, around which a bony tube makes 2.5 spiral turns. These turns contain scala vestibuli, scala tympani and scala media or Cochlear Duct. - The Scala Media or Cochlear Duct: - It is a triangular cavity filled with endolymph. - It contains the receptors of hearing which are called organs of Corti.

The Organ Of Corti It is present in the cochlear duct resting on the basilar membrane .

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Spiral Ganglion

Organ Of ( 'orti

Section In Cochlea - It consists of receptor hair ce11s and supporting cells. - The Hair Cells are neuroepithelial columnar cells with long micro villi. ·- They are arranged in 2 rows; inner hair cells and outer hair cells. The bases of hair cell~ are in synaptic contact with afferent nerve dendrites of the bipolar nerve cells of the spiral ganglia. - The Supporting Cells rest on the basilar membrane .

The Supporting cells are of the following three types: a- Inner and outer Pillar cells. They are rich in microtubules. b- Inner and outer Phalangeal cells which have cup-shaped upper ends occupied by the hair cells.

c- Border and Hensen cells which are columnar cells. The Tectorial Membrane is a rigid gelatinous membrane rich in mucopolysacchar ides. It is in touch with the microvilli of hair cells. The Scala Vestibuli is lined with simple squamous and is filled with perilymph.

The Scala Tympani is lined with simple squamous and is filled with perilymph . -90-

Inner

Outer

Tedorial

Outer Phalangeal

Ganglion

Organ Of Corti

The Vestibular Apparatus - It is formed of bony labyrinth which are: The vestibule and semicircular canals, these protect the membranous

labyrinth

which are: Utricle, Saccule and Semicircular ducts. - The membranous labyrinths are filled with endolymph and are surrounded by perilymph. - The utricle and saccule contain sensory organs called Maculae.

- Each Macula is formed of the following 3 types of cells: 1- Type I Hair Cells: Each cell is flask-shaped with long microvilli and with a single non motile cilium.

2- Type II Hair Cells are columnar cells with microvilli. Each cell has a single non motile cilium. -91-

3- Supporting Cells: They are columnar cells. The hair cells and supporting cells are covered by otolithic membrane which is rich in calcium.

Functions: The Maculae maintain body equilibrium in relation to gravity.

The Semicircular Ducts contain sensory organs called Cristae Ampullaris. Each Crista Ampullaris consists of 3 types of cells: Type I and type II hair cells and Supporting cells. They are covered with microvilli and cilia. - The microvilli and cilia are covered by a gelatinous membrane called

Copula which has no calcium carbonate crystals. - The basal parts of the hair cells are surrounded by the afferent nerve fibres which are the dendrites of the bipolar nerve cells of the

vestibular ganglia. Functions: The cristae ampullaris maintain body equilibrium m relation to head movements.

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The Central Nervou.i System (C.N.S) - It consists of the brain and the spinal cord.

The Brain Consists Of The Following Parts: a- The Brain Stem which includes: Midbrain, pons and medulla oblongata. b-Diencephalon which includes: Thalamus, subthalamus, hypothalamus and epithalamus. c- The Cerebrum. d- The Cerebellum.

metathalamus,

The Brain Meninges - They are the pia, the arachnoid and the dura maters. The Pia Mater is formed of vascular C.T and simple squamous epithelium. The Arachnoid Mater is formed of non-vascular C.T. The subarachnoid space contains The Cerebro-Spinal Fluid (C.S.F.) and brain blood vessels. Both, pai and arachnoid maters are adherent together and are called Leptomeninges The Dura Mater is formed of 2 layers of dense C. T. It contains The Venous Dural Sinuses which drain the C.S.F. and the venous blood of the brain. The Choroid Plexus are vascular projections of the pia mater present in the brain ventricles. They are covered by simple cuboidal cells called ependymal cells which secrete the C.S.F. The CerebroSpinal Fluid (C.S.F.) - Its amount is about 135 CC. It contains potassium, sodium, .chlorides, glucose and protein. - It c.irculates in brain ventricles, central canals of brain and spinal cord and in the subarachnoid space. - It is drained into the venous dural sinuses then back to the blood stream.

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- It acts as lymph drainage to brain tissue. - It acts as fluid cushon for the C.N.S. The Blood Brain Barriers The Blood Brain Barriers prevent harmful materials from entering the brain. They allow 02, C02 and nutrient substances to pass. The Blood Brain Barriers are Formed of : 1- Tight junctions between the adjacent endothelial cells which line

the brain blood capillaries. 2- The basement membranes of the brain blood capillaries. 3- The processes of neuroglia which surround the brain blood capillaries. /

The Spinal Cord - It is about 45 Cm in length. It is covered by meninges. - It becomes narrow at its end to form the conus medullaris. - It consists of these segments: 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal· - There are 31 pairs of spinal nerves. Each one is attached to its corresponding spinal cord segment by a dorsal and a ventral root. - It terminates opposite to the disc between first and second lumbar

vertebrae.

The Grey Matter Of The Spinal Cord - The H-shaped grey matter of the spinal cord contains: Nerve cells (Nuclei), Neuroglia cells and Blood capillaries, but no tracts. 1- The Nuclei (groups of nerve cells) of the posterior horns are sensory nuclei and are as follows: a- Posterior marginal nucleus (lamina I) for pain and touch. b- Substantia gelatinosa of Rolandi (lamina 2) for pam, temperature, touch and sexual sensations. c- Main sensory nucleus or Nucleus proprius (lamina 3 and 4) for touch sensation. d- Clark's nucleus (lamina 5 and 6). It is found in thoracic and upper lumbar segments only. It receives proprioceptive sensations.

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2- The Nuclei (nerve cells) Of Anterior Horns (laminae 8 and 9): -They are motor in function.

- They include the following 2 types of neurones: a- Alpha Neurones which are the large nerve cells . b- Gamma Neuroncs which are the small nerve cells 3- The Nuclei (nerve cells) Of Lateral Horns (lamina 7): -They are present only in thoracic and upper lumbar segments. -They give origin to sympathetic nerve fibres. -Similar neurones are found in sacral segments which give origin to parasympathetic nerve fibre s.

4- Associative Commissural Neurones (lamina 10): - They are present around the central canal. They are essential for reflex arc and visceral autonomic functions. - - - - - - -·-.Gracil Tract -----------Cuneate Tract ~ Lissauer's Tract

Poste . Column

~-...,..,Nuclei

ln Grey Matter

"!'---- Tracts In White Matter

An terior--..:::a:::.__....;: -:-,o .umn

Spinal Cord (Cervical Region) The White Matter Of The Spinal Cord It contains myelinated and non-myelinated nerve fibres. The tracts are separated by neuroglia and by blood capillaries.

The_Tracts are groups of nerve fibres having the ·same origin, the same termination and the same functions. The tracts are either short or long. The long tracts are either ascending or descending tracts.

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The Short Tracts Of The Spinal Cord are: a- Fasciculi Proprii which lie just outside the grey matter. They are the axons of the associative neurones of the grey matter~ They coordinate the functions of the different segments of the spin~l cord. b- Septomarginal tract is formed by descending fibres from gracil tract. It ends on anterior hom cells of lower half of body. c- Lissauer's tract is formed by the ascending and desceending short fibres of the lateral divisions of the posterior roots. They terminate in neurones of substantia gelatinosa of Rolandi. They carry pain, temperature, touch and sexual sensations. d- Comma-shaped tract is formed by descending fibres from cuneate tract. It ends on the anterior hom cells of upper half of body. The Long Ascending Sensory Tracts In Spinal Cord - The following tracts carJy body sensations to areas 3,1 ,2 of cerebral cortex of the opposite side. - The first order neurones of all sensations is located in the nerve cells of the dorsal root ganglia. - The second order neurones is located in posterior horn nerve cells or in nuclei of gracil and cuneate. - The third order neurones is located in the postero lateral ventral nucleus of the thalamus. Gracil Tract: It arises as axons of nerve cells of the posterior root ganglia of the lower half of the body. The fibres relay in the nerve cells of gracil nucleus. It carries proprioceptive and touch sensation from the lower half of the body. Cuneate Tract: .It arises as axons of nerve cells of posterior root ganglion of the upper half of the body. It relays in the nerve cells of cuneate nucleus. It carries proproiceptive and touch sensations froll,) the upper half of the body.

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\

Lateral Spino-thalamic Tract: It arises as axons of nerve cells of substantia gelatinosa of Rolandi. These axons cross to the opposite side. These axons relay in the nerve cells of thalamus. It carries pain, temperature and sexual sensations. Ventral Spino-thalamic Tract: It arises as axons of nerve cells of the main sensory nucleus of the spinal cord. These axons cross to the opposite side. The fibres relay in the nerve cells of the thalamus. It carries simple touch. The following tracts carry sensations to cerebellum: Dorsal Spino-Cerebellar Tract: It arises as axons of nerve cells of Clark's nucleus of the same side. This tract enters the cerebellum through the inferior cerebellar peduncle to terminate in the cerebellar nerve cells. It carries proprioceptive sensation from upper half of the body to cerebellum. Ventral Spino-Cerebellar Tract: It arises as axons of nerve cells of Clark's nucleus of the opposite side. The tract enters the cerebellum via the superior cerebellar peduncle to terminate in the cerebellar nerve cells. It carries proprioceptive sensation from the lower half of the body to cerebellum Spino-Olivary Tract: It arises as axons of the main sensory nucleus of the opposite side. It relay in the inferior olivary nucleus in the medulla, then olivo-cerebellar fibres arise from olivary nucleus to enter the cerebellum via the inferior cerebellar peduncle. It carries proprioceptive sensation to cerebellum. Spino Tectal Tract: It arises as axons of the main sensory nucleus of the opposite side. It terminates in the superior colliculus of the midbrain. It carries spino-visual reflexes. Spino Reticular Tract: It arises as axons of posterior horn cells. It terminates in the reticular formation of the brain stem. It influences consciousness.

.

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N.B: In Tabes Dorsalis Disease Of Syphilis, proprioceptive and touch sensations are lost giving rise to Sensory Ataxia which is characterized by Loss of: sense of position, vibration sense, stereognosis, discrimination and gait disturbance when the patient close his eyes. This test is called Romberg's Sign.

The Long Descending Motor Tracts In Spinal Cord They are classified into: 1- Pyramidal Tracts: They arise from cerebral cortex and form the pyramid in the medulla. They end by synapse on anterior horn cells. 2- Extrapyramidal Tracts They arise from nuclei in midbrain, pons and medulla. They end by synapse on anterior hom cells.

The Pyramidal Tracts They include the cortico spinal and cortico bulbar (nuclear) tracts.

The Cortico Spinal Tracts Origin: Arise as axons of Betz cc11s of area 4,6 of cerebral cortex . Pathway: The axons converge in the corona radiata, then in the internal capsule, then pass through midbrain, then pass through the pons. In the medulla oblongata, the bundles become grouped together to form the pyramids. In the medulla 90% of the corticospinal fibres cross and descend as lateral corticospinal tract (Crossed Pyramidal). They end by synapse on the anterior hom cells. - The non-crossed pyramidal fibres descend in the form of: a- Anterior Corticospinal Tract (8%) which descend to end by synapse on anterior horn cells of the opposite side. b- Antero-lateral Cortico-Spinal Tract. (2%) which descend to end by synapse on the nuclei of the lateral horn cells of the opposite side. Functions: The pyramidal tracts control the fine skilled movements. -98-

The Cortico Bulbar Or Cortico Nuclear Tracts They arise from cerebral cortex and synapse on the nuclei of the motor cranial nerves. They Are The Following: 1- The Medial Cortico Bulbar Tract arises as axons of Betz cells of area 8 of cerebral cortex. The tract descend in corona radiata, intemal capsule and midbrain. The fibres end by synapse on the nuclei of oculomotor nerves 3,4 and 6 and on the reticular formation of the midbrain. 2- The Lateral Cortico Bulbar Tract arises as axons of Betz cells of area 4 of cerebral cortex. They descend in corona radiata, intemal capsule and midbrain. The fibres end by synapse on the nuclei of 5,7,9,10,11 and 12 cranial nerves and in the reticular formation of pons and medulla.

The Extrapyramidal Tracts 1- Rubrospinal Tracts: They arise from the red nuclei of midbrain. They decussate and descend to end on the anterior hom cells. They have facilitatory effect on the flexor muscles. 2- Tectospinal Tracts: They arise from the superior colliculi of midbrain. They decussate to end on anterior hom cells of cervical segments. They regulate movements in relation to visual stimuli. 3- Olivospinal Tracts: They arise from inferior olivary nuclei. They descend to end on anterior hom cells of cervical segments. 4- Vestibulospinal Tracts: They arise from vestibular nuclei. They end on anterior hom cells. 5- Reticulospinal Tracts: They arise from the reticular formation of the brain stem. They end on anterior hom cells. The lateral reticulospinal tracts are inhibitory, while the ventral reticulospinal tracts are facilitatory in functions. 6- Sulcomarginal Tracts: They are the continuation of the medial longitudinal bundle.

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7- Descending Autonomic Fibres: They arise from cerebral cortex, hypothalamus and reticular formation. They end on the sympathetic and parasympathetic nuclei which are present in thoracic, lumbar and sacral segments. The Olivary Nuclei are four nuclei: The superior olivary nucleus is present in the pons. The inferior olive, the lateral and medial accessory olivary nuclei are present in the medulla. The Inferior Olivary Nuclei receive afferent fibres from: Cerebral cortex, Cerebellum, Red nucleus and from Spinal-cord. Olivary nuclei give efferent fibres to: Cerebellum ~d to spinal cord. The Medial Lemniscus: It is a bundle of nerve fibres present in the brain stem. It is formed of the internal arcuate fibres which arise from gracil and cuneate nuclei of the medulla. After sensory decussation of these fibres, they ascend on the opposite side in the brain stem as medial lemniscus. They then relay in the posterolateral ventral nucleus of the thalamus. From the thalamus sensory radiation arise to terminate in areas: 3,1,and 2 of cerebral cortex. They carry propr~oceptive sensations to cerebral cortex. The Spinal Lemniscus: It is a sensory bundle present in the brain stem. It is formed by the collections of the fibres of the lateral and ventral spino-thalamic tracts. The spinal lemniscus ascend in brain stem to relay in the P.L. V.N. ofthalamus. It carries pain, temperature, touch and sexual sensations to sensory cortex. N.B: In syringomyelia there is loss of pain and temperature sensation but touch sensation is not lost. This is due to destruction of spino thalamic tract fibres which pass in front of the dilated central canal of the spinal cord. Touch sensation is not lost because it is carried also by gracil and cuneate tracts.

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---:-:--Cuneate Nucleus Spinal ~ 4> Tngcmma. Tract Spino Cerebellar Tracts

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The Cranial Nerves The Hypoglossal Nerve (12th Cranial) - It is a pure motor nerve it supplies the muscles of tongue. Origin: From hypoglossal nucleus present in the floor of 4th ventricle in open medulla. Pathway: It runs between inferior olive and medial lemniscus. then between inferior olive and pyramid. Lesion of one hypoglossal nerve results in deviation of tongue towards the paralysed side when the tongue is protruded.

The Accessory Nerve (11th Cranial) The accessory nerve has the following 2 roots a- The Spinal Root arises from the anterior horn cells of the upper 5 cervical segments. It supplies the sternomastoid and trapezius muscles. b- The Cranial Root arises from lower part of nucleus ambiguous. It supplies the muscles of palate, pharynx and larynx.

The Vagus Nerve (lOth Cranial) The Vagus Nerve Has The Following 3 Nuclei: 1- Dorsal Motor Parasympatheti c Nucleus: It supplies the heart, the digestive and respiratory systems. 2- Middle Part of nucleus ambiguous: It supplies all muscles of larynx, pharynx and palate except stylopharyngeus and tensor palati. 3- Sensory Solitary Vagus Nucleus which is the lower part of nucleus solitarius. It receives sensation from external ear, pharynx, larynx, respiratory and digestive systems. It receives also taste sensation from epiglottis . N.B: Lesion of vagus nerve results in dysphagia (difficulty in swallowing) and dysphonia (difficulty in spcach).

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The Glossopharyngeal Nerve (9th Cranial) It has 2 motor nuclei and one sensory nucleus

1- It arises from upper part of nucleus ambiguous which is a motor nucleus. It supplies stylopharyngeus muscle. 2- It arises also from the ~nferior salivatory nucleus which is a parasympathetic nucleus. It supplies parotid gland. 3- It is attached to middle part of solitary nucleus which is a sensory nucleus. The glossopharyngeal nerve carries to it taste sensation from posterior third of tongue, general sensation from parotid, pharynx, carotid body and from external ear.

The Cochico-Vestibular Nerve (8th Cranial) The 8th. Cranial Nerve is formed of 2 parts. 1- Cochlear Nerve concerned with hearing. 2- Vestibular Nerve concerned with equilibrium.

The Cochlear or Auditory Pathway Origin: The Cochlear Nerve arises as axons of the bipolar nerve cells of spiral ganglia in the internal ear (First order neuron). Pathway: It leaves the ear and ascends to be attached to the dorsal and ventral cochlear nuclei of the pons. (Second Order Neuron) Axons of the ventral cochlear nucleus cross to the opposite side to form the Trapezoid body then ascend in the\ brain stem as Lateral Lemniscus. The fibres of the lateral lemniscus end by synapse on nerve cells of Inferior Colliculus and of the Medial Geniculate

Body. The cochlear pathway is also interrupted by certain nerve cells (nuclei) in superior olive, trapezoid body and in the lateral lemniscus. The Auditory Radiation. The axons of nerve cells of the medial geniculate body form the auditory radiation which end by synapse .on nerve cells of the auditory cerebral areas (41 and 42). Lesion of cochlear nerve results in perceptive deafness~

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Cochlea

Eye Ball

Liver Injected With Gelatin Carmine To Demonstrate Its Vasculature.

Kidney Injected With Gelatin Carmine To Demonstrate Its Vasculature

Von Kupffer Cells In The Wall

Glycogen Granules In Liver Cells (Best Carmin Stain)

Liver Stained With Silver To Demonstrate Its ReticularC.T.

Identification Of Histological Sections In The Different Regions Of The Central Nervous System. - Weighert-Pal stains the white matter w ith black co lou r, whil e the grey matter is not stained.

- Silver stains the grey matter with dark brown and the white matter with yellow co lour.

- Hematoxylin stain the grey matter with clark blue and the white matter with

pale~staining

.

Spinal Cord at Cervical Region The 2posterior horns are thin and divergent whi le the 2 anterior horns are slightly thick Hemat~oxylin

Weighert-Pal Stain

Spinal Cord at Thoracic Region - Both anterior and posterior horns are thin. - Small lateral horns are present at both sides.

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Spinal Cord at Lumbar Region

- Both anterior and posterior horns are thick and not aivergent.

stain

Closed Medulla at Motor Decussation. -Graci ! and cuneate tracts are large . -The Pyramidal tracts are smal l Weigcrt-Pal Stain

Silver Stain

Closed Medulla at Sensory Decussation -Grac i! and c un eate tracts are sma ll. -The pyramidal tracts are large.

Open Medulla - It has no central , canal beca use it "opened" in the floor of fourth ventricle. - It contains the convoluted inferior olivary nu clei .

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Pons at Its Inferior Level. - T he fo urth ventricle is present at its dorsal aspect and is covered by part of the cerebellum. -Tra nsverse pontine f ibres are present in the basis pon ti s.

Mid-brain at Inferior Colliculus -Aqued uct of Sylvius is surrounded by grey matter. -The crus cerebri and substantia nigra are present in the basis pedunculi.

Mid-brain at Superior Colliculus -Aq ued uct of Sy lviu s is surrouded by grey matte r. - Two Red nuclei appear at both sides of th e tegmentum of midbrain -Oculomotor nerve f ibres emerge from the anterior border of mid brain - Crus. cerebri and substanti a nigra are present in the bas is pedunculi.

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Cerebellum. Section in the cerebe llum is characterised by the presence of arborisations like the leaves of a tree called folia. Each folium is formed of a central pale area (white matter) and a peripheral clark area (grey matter).

Cerebrum Its convoluted gyri consists of grey matter overlying central mass of white matter.

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Other Book By The Same Author Is Coming Soon "In Shaa ALLAH" A Book With Questions And Answers For Oral And Theoretical Examinations.

I.S.B.N. 977-19-3 612-3:

.)J..LJt ~r)t

AL-Shaa b Printing House

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