Inhibition of ovarian follicle growth by a chemical antiestrogen.

Effect of a chemical antiestrogen, cis-clomiphene, on FSH-induced ovarian follicle growth was studied morphometrically in hypophysectomized immature female rats. NIH-FSH-S12 alone or in combination with cis-clomiphene was injected to hypophysectomized rats and the ovarian weight, histological findings of the ovary, the number of growing and atretic follicles, the uptake of tritiated thymidine by the ovary and labelling indices of growing follicles were investigated with reference to their morphometric aspects. A chemical antiestrogen, cis-clomiphene, inhibited FSH-induced ovarian follicle growth. The results suggest that endogenous estrogen secretion plays a role in the ovarian response to FSH, and FSH-induced follicular growth is mediated by endogenous estrogen.