FSH stands for follicle stimulating hormone. \u00a0To my knowledge, males don’t even have follicles; females do. \u00a0LH stands for luteinizing hormone; once again, the name refers to a structure found in the female reproductive system, rather than the male. \u00a0However, FSH and LH are used by the hypothalamus to control the reproductive function of both sexes. The hypothalamus does not release either LH or FSH; rather, it causes the pituitary to do so. \u00a0Negative feedback figures prominently in this control system.<\/p>\n
In the male, LH targets the interstitial cells in the testis, causing them to release testosterone. \u00a0The hypothalamus monitors the testosterone level in the blood. \u00a0In answer to the testosterone level being correct, the hypothalamus relaxes its demand of the pituitary to release LH. \u00a0This situation can be referred to as negative feedback: \u00a0once the low level of testosterone is corrected, the hypothalamus stops its corrective action. Less LH means less stimulation of the interstitial cells, so they in turn produce less testosterone. \u00a0 Yet, if the testosterone level falls again, the hypothalamus will once again cause the pituitary to release LH in order to stimulate the interstitial cells once more. So the cycle continues: \u00a0low level, corrective action, refreshed level, cease of corrective action, and so on.<\/p>\n
FSH targets the seminiferous tubules in the testis, causing them to produce sperm and, at the same time, inhibin. \u00a0The blood’s inhibin level is monitored by the hypothalamus for the purpose of negative feedback. \u00a0Since the inhibin is produced alongside sperm, the hypothalamus can monitor the inhibin level in order to track the level of sperm production.<\/p>\n
For a description of negative feedback, see my post here<\/a>. For a treatment of the action of LH and FSH in the female, see my next post:)<\/p>\n Source: Mader, Sylvia S. Inquiry into Life<\/em>, 11th edition. New York: McGraw-Hill, 2006.<\/p>\n