Ward Round Notes

The male reproductive system consists of the testes, a series of ducts, accessory glands and supporting structures. Sperm is produced in the testes. It then flows into the epididymis where it is stored, before it is propelled through a series of ducts to the exterior. The sperm matures within the ducts. Accessory sex glands secrete substances necessary to protect the gametes and to facilitate their movement along different portions of the ducts. The supporting structures play several roles including the delivery of sperm into the female reproductive tract and the support of the testes.

Unlike oogenesis, spermatogenesis occurs at puberty. Spermatogenesis occurs in the seminiferous tubules of the testes, and takes between 65 and 75 days to occur. However about 300 million sperm complete spermatogenesis each day. Spermatogenesis begins with spermatogonia (spermatogonium s.)  found beneath the basement membrane of the seminiferous tubules. The spermatogonia are sperm cells which are undifferentiated and undergo mitosis. The cells which remain near the basement membrane remain as a reservoir of undifferentiated cells, whereas those which loose contact squeeze through a blood-testis barrier and differentiate into primary spermatocytes .

Oogenesis The production of female gametes begins before birth. Primordial germ cells migrate from the yolk sac of the embryo to the gonads (reproductive organs), where they differentiate into oogonia. Oogonia undego multiple mitotic divisions, and are arranged in clusters surrounded by a layer of epithelial/follicular cells by the end of the 3 rd month of development. The oogonia continues to divide, however some of them start meiosis, arresting at the diplotene stage of meiosis 1(stage when crossing over occurs). These are now called primary oocytes. The number of germ cells in the ovaries reaches its maximum at about 5 months of gestation, at around 7 million. After 5 months, a portion of oogonia and primary oocytes begin to degenerate becoming atretic. By the 7 th month, most cells hav degenerated except for those near the surface, these have all entered meiosis 1 and most are surrounded by a layer of epithelial cells. A primary oocyte together with the epithelial cells is c...