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Spermatogenesis, the process for producing spermatozoa, takes place in the seminiferous tubules. During spermatogenesis, the DNA of spermatogenic cells in the seminiferous tubules is subject to damage from such sources as reactive oxygen species. [1] The genomic integrity of spermatogenic cells is protected by DNA repair processes. [2]
Thus, spermatogenesis is the male version of gametogenesis, of which the female equivalent is oogenesis. In mammals it occurs in the seminiferous tubules of the male testes in a stepwise fashion. Spermatogenesis is highly dependent upon optimal conditions for the process to occur correctly, and is essential for sexual reproduction.
This is particularly so considering that bicalutamide increases circulating testosterone levels, and by extension gonadal testosterone production, by up to two-fold in males, [88] and that only a small fraction of normal intratesticular testosterone levels, and by extension androgen action, appears to be necessary to maintain spermatogenesis.
Because its main function is to nourish developing sperm cells through the stages of spermatogenesis, the Sertoli cell has also been called the "mother" or "nurse" cell. [10] Sertoli cells also act as phagocytes, consuming the residual cytoplasm during spermatogenesis. Translocation of cells from the basal lamina to the lumen of the ...
The onset of puberty is controlled by two major hormones: FSH initiates spermatogenesis and LH signals the release of testosterone, [19] an androgen that exerts both endocrine activity and intratesticular activity on spermatogenesis. LH is released from the pituitary gland, and is controlled by pulses of gonadotropin-releasing hormone.
An average adult testicle measures up to 5 cm × 2 cm × 3 cm (2 in × 3 ⁄ 4 in × 1 + 1 ⁄ 4 in). The Tanner scale , which is used to assess the maturity of the male genitalia, assigns a maturity stage to the calculated volume ranging from stage I, a volume of less than 1.5 cm 3 ; to stage V, a volume greater than 20 cm 3 .
Spermatogenesis is a very regulated process controlled by endocrine stimuli. These stimuli include the follicle-stimulating hormone (FSH) and the luteinizing hormone (LH), which stimulate testosterone. These hormones produce regulatory signals that control the maintenance and nutrients needed for the developing germ cells.
Spermatogonia going through mitosis to form primary spermatocytes in Grasshopper testes. Spermatocytogenesis. At puberty, spermatogonia located along the walls of the seminiferous tubules within the testis will be initiated and start to divide mitotically, forming two types of A cells that contain an oval shaped nucleus with a nucleolus attached to the nuclear envelope; one is dark (Ad) and ...