Spermatogenesis is maintained by which hormones (s): (PGI Dec 2008)
Ans : A (Testosterone); B (FSH) & C (LH) Testosterone, FSH & LH play essential roles in spermatogenesisHormonal Factors that Stimulate Spermatogenesis -Guyton 11th/998-999Testosterone - Secreted by Leydig cellsQ is essential for growth & division of the testicular germinal cells. which is first stage in forming sperm.Luteinizing Hormone - Secreted by anterior pituitary. Stimulates the Leydig cellsQ to secrete testosteroneQFSH - StimulateQ sertoli cells. Without this stimulation, the conversion of the spermatids to sperm will not occurEstrogen - Formed from testosterone by sertoli cells when they are stimulated by FSH ,are probably also essential for spermatogenesis.Growth Hormone (as well as most of the other body hormones)Is necessary for controlling background metabolic functions of testis. GH specifically promotes early division of the spermatogonia themselves; in its absence, spermatogenesis is severely deficient or absent, thus causing infertility."FSH make a important but not essential role in spermatogenesis Androgen may reach high concentration locally in the testis & are essential for spermatogenesis. Several cytokines & Growth factors are also involve by paracrine & autocrine mechanismHarrison 16th/2187FSH & Androgen maintain the gametogenic function of the testis. After hypophysectomy, injection of LH produces a high local concentration of androgen in the testis & this maintain spermatogenesis. The stage from spermatogonium to spermatids appear to androgen independent. However maturation from spermatids to spermatozoa depend on androgen. FSH act on sertoli cell to facilitate the last stage of spermatid maturation. The estrogen content of the fluid in rete testis is high. If this does not occur the sperm entering the epididymis are diluted in a large volume of fluid & infertility results"- Ganong 22nd/424-426Also know the factsThe testes is normally maintained at a temperature of about 32degCdeg (Ganong 22nd/427)'Spermatogenesis begins at an average age of 13 yrs (12- 14)deg (Guyton 11th/996)The estimated number of spermatids formed from asingle spermatogonium is 512. In humons, it takes an average of 74 days0 to form a mature sperm from a primitive germ celt (Ganong22nd/425)Scrotum temperature is 2degC below the internal temperature of body (Guyton 11th/1001)
Testosterone
FSH
LH
Prolactin
Sex Hormones