Testosterone is secreted by the interstitial (Leydig) cells of the testes under the influence of pulsatile secretion of LH from pituitary. FSH is mainly responsible for promotion of spermatogenesis in tubular (Sertoli) cells.
REGULATION OF SECRETION
Testosterone is
secreted by the interstitial (Leydig) cells of the testes under the influence
of pulsatile secretion of LH from pituitary. FSH is mainly responsible for
promotion of spermatogenesis in tubular (Sertoli) cells. The mediator of
feedback relationship with pituitary is uncertain. While relatively high
concentration of testosterone inhibits LH secretion and in time causes atrophy
of interstitial cells, it has only weak inhibitory action on FSH secretion.
Estrogens are more potent inhibitors of Gn secretion even in males and it is
believed that the small amount of estradiol produced by testes and that
resulting from conversion of testosterone to estradiol plays a role in feedback
inhibition. Inhibin, (a protein)
produced by Sertoli cells, has strong FSH inhibitory action and may be
mediating the feedback inhibition. Testosterone and estradiol act on
hypothalamus to reduce GnRH as well as act directly on pituitary. The plasma
level of testosterone in adult males ranges from 0.3 to 1 μg/dl and in females
from 20 to 60 ng/dl.
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