ENGLISH

Life Story of a Successful Sperm

Life Story of a Successful Sperm

Spermatogensis

Spermatogenesis in humans normally begins in pubertal period (about 12 years) and continues until the ripe old age. Duration of complete spermatogenesis in men is approximately 73-75 days. One cycle of the germinal epithelium takes approximately 16 days.

Sperm are produced in the testes, namely in the convoluted seminiferous tubules. The wall of the seminiferous tubules of the shares in the basement membrane and the luminal side adlyuminalnuyu. On the luminal side are Sertoli cells ( sustentotsity ) and precursors of germ cells (spermatogonia, spermatocytes I and II orders and spermatids). Spermatogonia, which lie directly on the basal membrane of the convoluted seminiferous tubules, go through several successive stages of mitotic division. The total number of spermatogonia in the testis of males about 1 billion there are two main categories of spermatogonia A and B. A spermatogonia, which divide mitotically, retain the ability to divide and maintain their population. Others defferentsiruyutsya in spermatogonia in which "evacuated" cellular contacts sustentotsitov (form the basis for a new sex cell contact and resorb old). In the spermatogonia divided mitotically, in differentiating spermatocyte I order coming into meiosis.

The complex process of spermatogenesis is regulated by gonadotropic hormones of the pituitary and testicular steroid hormones. After puberty, the hypothalamus begins to secrete gonadotropic releasing hormone, which is under the influence of the pituitary gland secretes follicle stimulating hormone (FSH), which stimulates the development and function of Sertoli cells and luteinizing hormone (LH), which stimulates the Leydig cells to the development of testosterone . Testosterone has an impact on the development of Sertoli cells, as well as precursors of germ cells (in association with androgen-binding protein secreted by Sertoli cells).

Spermatids then undergo a phase of cytodifferentiation that turn them into sperm. During this phase we observe:

The fusion of a dictyosomes acrosome vesicle, which stands in front of the cell,

Processing of the kernel which is more compact,

The appearance of a flagellum behind the cell

The loss of a part of hyaloplasm,

The hyaloplasm is a slimy substance that is a vital substance of a cell, bathing the organelles of cells. It corresponds to the gel comprising the cytosol and the cytoskeleton. With organelles cell, they form the cytoplasm. A dictyosome is a stack of cisternae membrane disc-shaped part of the Golgi apparatus of a cell. The Golgi apparatus may consist of one or more depending on the type of dictyosomes ...