ملخص Male (1).docx

**Seminiferous Tubules** (Figures 7-2 and 7-3): \- Are long, narrow and highly convoluted exocrine tubules lined with a special epithelium called the **germinal or seminiferous epithelium**. \- This **germinal or seminiferous epithelium** consists of two types of cells: 1\. Stratified renewing **...

**Seminiferous Tubules** (Figures 7-2 and 7-3): \- Are long, narrow and highly convoluted exocrine tubules lined with a special epithelium called the **germinal or seminiferous epithelium**. \- This **germinal or seminiferous epithelium** consists of two types of cells: 1\. Stratified renewing **spermatogenic cells**. 2\. Unilaminar , supportive **Sertoli cells**. \- The epithelium rests on a basal lamina and an underlying layer of CT enveloping the seminiferous tubules called **tunica propria** consisting of collagen, elastin and several layers of fibroblasts. **Spermatogenic cells:** \- Several layers in-between Sertoli cells. \- Represent the different stages of spermatogenesis. \- The successive order of spermatogenic cells arranged from the basement membrane to the lumen includes: 1\. Spermatogonia (stem cells). 2\. Primary and secondary spermatocytes (proliferating cells). 3\. Spermatids (differentiating cells). 4\. Spermatozoa (exfoliating cells). **I -- Spermatocytogenesis** (Figure 7-4): \- The phase in which spermatogonia generate the spermatocytes as well as replicate themselves. \- Spermatogonia are relatively small cells. \- 3 types of spermatogonia are recognized. 1\. **Type A dark** (Ad) cells: have ovoid dark nuclei and serve as **reserve stem cells**. 2\. **Type A pale** (Ap) cells: have ovoid pale nuclei, undergo mitotic division. Some of the daughter cells remain as type Ap cells for self renewal. The other daughter cells differentiate into type B spermatogonia. 3\. **Type B cells**: divide mitotically producing **primary spermatocytes** which are numerous and rounded and are the largest cells. **II -- Meiosis (Figure 7-4):** **First meiotic division:** N.B. s-chromosome is formed of one chromatid, while d-chromosome consists of two chromatids formed by duplication of DNA in the synthesis (S) phase of cell cycle. **Prophase:** \- The cell passes through the following stages (Figure 7-5): 1- Leptotene: 2- Zygotene: 3- Pachytene: 4- Diplotene: 5- Diakinesis: **III- Spermiogenesis** (Figure 7-6): \- The most involved organelles in the process of spermiogenesis are; the Golgi area, centrioles, mitochondria, and the nucleus. **The acrosomal phase:** \- The anterior pole of the cell becomes oriented toward the base of seminiferous tubule. **The maturation phase:** \- The cytoplasm moves to cover a part of the flagellum. \- Residual cytoplasm is shed and phagocytosed by Sertoli cells. \- Spermatozoa are released into the lumen of the tubule. 172 seminiferous tubule. \- The nucleus becomes more elongated and condensed, and surrounded by a cylinder of microtubules (the manchette). \- One of the centrioles grows at the same time, forming the flagellum. \- The mitochondria aggregate around the proximal part of the flagellum forming a region called the middle piece. They are the source of energy needed for the movement of the tail of the spermatozoon. **The maturation phase:** \- The cytoplasm moves to cover a part of the flagellum. \- Residual cytoplasm is shed and phagocytosed by Sertoli cells. \- Spermatozoa are released into the lumen of the tubule.  The duration of spermatogenesis, from the stem cell to spermatozoa is 64 + 4.5 days. During spermatogenesis, the cells resulting from division of the same spermatogonium remain attached by narrow cytoplasmic bridges, forming clones. **The mature spermatozoon** (Figure 7-7)**:** \- The human spermatozoon is about 65 um in length. \- It consists of head, neck and tail. 1\. **The head:** (5 um) contains the nucleus with its haploid genetic material and the acrosome (head cap). 2\. **The neck:** an area of connection between head and tail. It contains a pair of centrioles, the distal one forming the axoneme of the flagellum (the tail). 3\. **The tail:** Is subdivided from anterior to posterior into three segments; middle, principal and end pieces. **Sertoli cells** (Figure 7-8)**:** \- Sertoli cells are elongated pyramidal cells that extend from the basement membrane to the luminal surface of the seminiferous tubules. \- They have many cytoplasmic processes that partially envelop the developing spermatogenic cells. So, in the light microscope, their outlines are poorly defined. \- The nucleus is elongated or triangular in shape with prominent nucleolus and mainly extended chromatin. **Interstitial (Leydig) cells** (Figure 7-2) \- By the E/M, it is a typical *steroid secreting cell*, showing (Figure 7-9): 1\. Abundant SER. 2\. Many mitochondria with tubular cristae. 3\. Lipid droplets. **Genital Ducts:** **A) Intratesticular Genital Ducts** (Figures 7-1 and 7-11)**:** **1 -- Tubuli Recti** \- Tubuli recti are lined by simple cuboidal epithelium and they connect the seminiferous tubules with the rete testis. **2 -- Rete Testis:** It is a highly anastomosing network of channels lined with simple cuboidal epithelium and is present within the mediasinum testis. **3 -- Ductuli Efferentes:** \- They are lined by two types of cells, in groups alternating with each other: 1\. Non ciliated cuboidal absorptive cells that absorb the testicular fluid. 2\. Ciliated columnar cells whose cilia beat in the direction of the epididymis helping in sperm transport. **1 -- The Epididymis** \- The ductus epididymidis is lined by pseudostratified columnar epithelium composed of (Figure 7-13): 1\. Rounded basal cells. 2\. Columnar cells having long slender microvilli (stereocilia). **2 -- The Ductus (Vas) Deferens** A\) The mucosa: 1\. Epithelium; pseudostratified columnar epithelium with stereocilia. 2\. Lamina propria; a layer of C.T. rich in elastic fibers. **ACCESSORY GENITAL GLANDS** **1 -- The Seminal Vesicle:** \- The wall consists of (Figure 7-15): 1\. Mucosa which is thrown into a complex series of primary, secondary and tertiary folds.  The lining epithelium is pseudostratified columnar. The columnar cells show the ultrastructure of protein synthesizing cell.  The lamina propria is rich in elastic fibers.