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2. The digestive system is a collection of organs that work together to digest and absorb food. Digestion is the process the body uses to break down foods into molecules that the body can use for energy and nutrients Lab Exercise # 6Zoo- 145 Organs of the digestive system The Digestive System

3. The digestive system consist of oral cavity with its accessories parts and the digestive tract with its accessories glands The digestive tract or Gastro Intestinal Tract (GIT) includes: 1.Oesophagus 2.Stomach 3.Small intestine 4.Large intestine Every section through the digestive tract shows that each of the part is composed of four different layers Lab Exercise # 6Zoo- 145 SerosaMusculature (Muscularis) Submucosa Mucosa

4. Oesophagus is a muscular tube connects the pharynx with the stomach Its wall consist of four layers Serosa:Outermost layer is composed of Simple Squamous Epithelium Musculature: Three layers thick, two layers of Longitudinal Muscle Fibers and a layer in between is composed of Circular Muscle Fiber Submucosa: It is composed of Connective tissue Mucosa: It is composed of stratified squamous epithelial Lab Exercise # 6Zoo- 145 The Oesophagus

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6. Stomach is the dilated segment of the digestive tract The wall of the stomach is formed of four layers: Serosa: It is composed of connective tissue and squamous epithelium Musculature: Two layers, one each from longitudinal (LMF) and circular muscle fibers (CMF) Submucosa: It is composed of connective tissue Mucosa: It is thick and lined marginally with simple squamous epithelium and peptic and oxyntic cells. Peptic cells are secreting peptic enzymes and oxyntic cells secrete HCL acid Lab Exercise # 6Zoo- 145 The Stomach

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8. Liver Is the largest metabolic organ in the body the liver formed of a stroma of connective tissue and parenchyma of liver cells (hepatocytes) All of the cells in the liver are called hepatic cells and these are arranged in lines in the unit of liver called hepatic lobules (Hexagonal shape). Each such line of the hepatic cells is called hepatic strand. The space in between hepatic strands is filled with blood and it is called hepatic sinusoid. In the centre of each hepatic lobule there is hole called central vein Lab Exercise # 6Zoo- 145 The Liver

9. Lab Exercise # 6Zoo- 145 The connective tissue septa cornered between 3 hepatic lobules is called portal space or area, which contains the following structures: 1- Branch of hepatic artery 2- Branch of portal vein 3- Bile ductule 4- Lymph vessel The Liver

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11. The Testis is both an exocrine and an endocrine organ. The exocrine portion consists of a series of highly coiled seminiferous tubules that make sperm the endocrine portion consists of specialized cells called interstitial cells (also called Leydig cells) that secrete testosterone. The Interstitial Cells lie in the connective tissue between adjacent coils of seminiferous tubules Two TestesDifferent tubules Accessory Glands Male Reproductive System Epididymis Vas Deference Ejaculatory duct Seminal Vesicles Prostate Gland Cowper’s Gland Lab Exercise # 7Zoo- 145

12. Lab Exercise # 7Zoo- 145 The Testis Testis is composed of functional units termed seminiferous tubules. Seminiferous tubules are bound together with connective tissue termed as inter tubular connective tissues. The outer layer of the testis is called tunica albugenia. Spermatogonia are transformed meiotically into primary spermatoctes then in secondary spermatocytes and spermatids. Finally spermatids are transformed into sperms.

13. The seminiferous tubule is highly convoluted tubule lined by the following cells: 1- Spermatogenic cells: The spermatogenic cells consist of five morphologically distinct classes of cells: Spermatogonia, Primary Spermatocytes, secondary spermatocytes, spermatids, and spermatozoa. 2- Sertoli cells: Sertoli cell is supporting cells, columnar cells with irregular nuclei. These cells are extend from basement membrane to the lumen of the seminiferous tubule. Lab Exercise # 7Zoo- 145

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15. OvaryOviduct (Fallopian Tube) Uterus Female Reproductive System The Ovary is a large, almond-shaped structure covered by germinal epithelium The ovary consist of : 1- Peripheral cortex Primordial follicles. Primary follicles. Secondary follicles. Growing follicles. Mature Graaffian follicles. Atretic follicles. Corpus luteum Lab Exercise # 7Zoo- 145 2- Central medulla The medulla of ovary is small part compared to the cortex, its connective tissue contains many spiral arteries and convoluted veins.

16. Ovary is covered by a simple Cuboidal Epithelium known as the germinal epithelium (GE). Beneath the Germinal Epithelium lies a tough connective tissue coat, the Tunica Albuginea (TA). The tunical albuginea outlines the outer part of the Ovary, the cortex, in which the developing follicles lie. The core of the Ovary, called the Medulla (M), is made up of connective tissue through which blood vessels (V) pass Lab Exercise # 7Zoo- 145 The Ovary

17. Lab Exercise # 7Zoo- 145 Micro anatomically every ovary is composed of marginal layer of epithelium, peritoneal layer and then a germinal layer which are meitotically transformed into primary oocytes then secondary oocytes and graaffian follicles. Finally graaffian follicles are grown into mature ova. The space left by graaffian follicle is called corpus luteum which acts as an endocrine gland. The tissue that binds the cells together in the ovary is called stroma and it is a combination of muscular tissue with connective tissue.

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