Spermatogenesis

Teo Kah Cheng

A

process by which male spermatogonia develop into mature male spermatozoa.  In mammals, it occurs in the male testes and epididymis, for humans it takes approximately 64 days.  It starts at puberty, and usually continues uninterrupted until death.

 Spermatogenesis

produce mature male gametes, commonly called sperm, which are able to fertilize female gamete, the oocyte.  During conception, to produce zygote, the sexual reproduction involves two gametes contributing half the normal set of chromosomes (haploid) to result in chromosomally normal (diploid) zygote.

A

diploid spermatogonium divides mitotically to produce two diploid intermediate cell called a primary spermatocyte.  Each primary spermatocyte duplicates its DNA and subsequently undergoes meiosis I to produce two haploid secondary spermatocytes.

 The

division implicates sources of genetic variation such as chromosomal crossover, to increase the genetic variability of the gamete.

 The

initiation of spermatogenesis usually involves the interaction of the hypothalamus, pituitary gland and Leydig cells.  Cells of Leydig synthesize the testosterone which stimulates the vertebrate germ cell differentiation.  The production of testosterone by the cells of Leydig is regulated by luteinizing hormone

 Follicle-stimulating

hormone (FSH) acts on the Sertoli cells in mammals to stimulate the release of androgen-binding protein (ABP).  This protein is essential to concentrating testosteron in levels high enough to initiate and maintain the spermatogenesis.