Effects of human chorionic gonadotropin, human interstitial cell stimulating hormone and human follicle-stimulating hormone on ovarian weights in estrogen-primed hypophysectomized immature female rats.

In connection with systematic studies of steroid and peptide hormone interactions during follicular growth, we have measured ovarian weight responses to graded doses of highly purified human chorionic gonadotropin (hCG), human interstitial cell stimulating hormone (hICSH)in hypophysectomized immature female rats (HIFR) treated with diethylstilbestrol in silastic capules (desc) implanted subcutaneously. Our results are consistent with earlier reports of enhancement of ovarian weight responses to hCG and FSH. Contrary to results of similar experiments reported by others, we have found that estrogen treatment of HIFR enhanced ovarian weight response to ICSH. In addition, we report for the first time that small doses of hCG and hICSH inhibit ovarian weight responses to estrogen in HIFR. Our observations on effects of small doses of hCG and hICSH and the long-known fact that ovarian interstitial cells are stimulated in HIFR given similar doses of these hormones lead us to hypothesize that ovarian interstitial cell stimulation is involved in the control of follicular maturation.