In human male reproductive system, The onset of puberty, hypothalamus begins secreting high pulses of GnRH, or gonadotropin-releasing hormone. In response, the pituitary gland releases follicle stimulating hormone (FSH) and luteinizing hormone (LH) into the male system for the first time. FSH enters the testes, stimulating the sertoli cells, which help to nourish the sperm cells that the testes produce, to begin facilitating spermatogenesis. LH also enters the testes, stimulating the interstitial cells, called leydig cells, to make and release testosterone into the testes and the blood.
Testosterone, the hormone responsible for the secondary sexual characteristics that develop in the male during adolescence, stimulates spermatogenesis.
When rising levels of testosterone act on the hypothalamus and anterior pituitary to inhibit the release of GnRH, FSH, and LH. The sertoli cells produce the hormone inhibin, which is released into the blood when the sperm count is too high.