Spermotogenesis (the making of sperm)
The seminiferous tubules consist of a basement membrane lined by the seminiferous/germinal epithelium. this epithelium consists of two types of cells:
Diplod- these cells develop from the primordial (primitive) germ cells these enter the testes early in embryonic development, from these cells sperm originate, they will remain dormant until they begin to undergo mitotic proliferation at puberty.
sertoli or nurse cells - these support and nourish the germ cell, the younger the germ cell the closer it lies to the wall of the tubule these cells divide miotically to produce diploid daughter cells, these are called spermatogonia and they pass nearer to the lumen of the tubule. the spermatogonia will increase in size with out dividing and they become primary spermatocytes these again will divide mitotically to become spermatids. finally they transform to spermatozoa this will occur in the part of the wall that is adjacent to the lumen, as they mature the sperm will become attached to the Sertoli cells to obtain their nourishment. the tails of the sperm project in to the fluid-filed lumen of the tubule, and eventualy they will become detached and released into the lumen. for a horse sperm production will take 50 days but 70 in the human.
(Tortora & Grabowski, Reynolds, 1996)
Diplod- these cells develop from the primordial (primitive) germ cells these enter the testes early in embryonic development, from these cells sperm originate, they will remain dormant until they begin to undergo mitotic proliferation at puberty.
sertoli or nurse cells - these support and nourish the germ cell, the younger the germ cell the closer it lies to the wall of the tubule these cells divide miotically to produce diploid daughter cells, these are called spermatogonia and they pass nearer to the lumen of the tubule. the spermatogonia will increase in size with out dividing and they become primary spermatocytes these again will divide mitotically to become spermatids. finally they transform to spermatozoa this will occur in the part of the wall that is adjacent to the lumen, as they mature the sperm will become attached to the Sertoli cells to obtain their nourishment. the tails of the sperm project in to the fluid-filed lumen of the tubule, and eventualy they will become detached and released into the lumen. for a horse sperm production will take 50 days but 70 in the human.
(Tortora & Grabowski, Reynolds, 1996)