It is therefore proposed that gynecomastia probably results from failure of adequate testosterone action on the breast primordia during embryonic differentiation. Follicle cells produce the hormone inhibin, which inhibits FSH production. Main article: Sexual selection in human evolution.
The handicap principle extends this idea, stating that a peacock 's tail, for instance, displays fitness by being a useless impediment that is very hard to fake. Sertoli cell cell in seminiferous tubules that assists developing sperm and makes inhibin. Other hormones have specific functions in the male and female reproductive systems.
These secondary sex characteristics include a deepening of the voice, the growth of facial, axillary, and pubic hair, and the beginnings of the sex drive. FSH stimulates follicles on the ovary to grow and prepare the eggs for ovulation. Rising and falling hormone levels result in progression of the ovarian and menstrual cycles.
FSH enters the testes and stimulates the Sertoli cells to begin facilitating spermatogenesis using negative feedback, as illustrated in. Charles Darwin hypothesized that sexual selectionor competition within a species for mates, can explain observed differences between sexes in many species. For boys, puberty begins around age 10 to 14 years and lasts about hormones and secondary sex characteristics in boys in Welland years.
The handicap principle extends this idea, stating that a peacock 's tail, for instance, displays fitness by being a useless impediment that is very hard to fake.
American Naturalist. Hidden categories: Harv and Sfn no-target errors Webarchive template wayback links All articles with unsourced statements Articles with unsourced statements from October Menopause occurs when the ovaries lose their sensitivity to FSH and LH and the female reproductive cycles slow to a stop.
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In females, breasts are a manifestation of higher levels of estrogen ; estrogen also widens the pelvis and increases the amount of body fat in hips, thighs, buttocks, and breasts. The Sertoli cells produce the hormone inhibin , which is released into the blood when the sperm count is too high.
LH also enters the testes and stimulates the interstitial cells of Leydig to make and release testosterone into the testes and the blood. Search for:. Although at puberty he has signs of virilization, he has developed pronounced gynecomastia.