Inhibition of the ovarian augmentation reaction by a chemical antiestrogen

Inhibition by antiestradiol serum of ovarian weight gain and follicular growth in hypophysectomized immature rats given FSH and hCG suggested that gonadotrophin induced endogenous estrogen secretion plays a role in the ovarian augmentation reaction. We have studied the effects of a chemical estrogen antagonist, cis-clomiphene, on ovarian weight response to gonadotrophins in hypophysectomized immature female rats. We found that this antiestrogen inhibits the ovarian response to FSH and hCG. To our knowledge, this is the first demonstration of a direct effect of a chemical antiestrogen on the ovary, a result consistent with a role for intraovarian estrogen in follicular growth.