Systemic versus intraovarian progesterone replacement after luteectomy in rhesus monkeys: differential patterns of gonadotropins and follicle growth.

Similar to luteectomy (CLX) alone, systemic replacement of progesterone (P) to maintain circulating midluteal phase levels after CLX, and P withdrawal 10-11 days later were not accompanied by changes in serum FSH or LH levels. The next preovulatory gonadotropin surges, however, were delayed by about 10 days, relative to CLX alone. In contrast, a marked rise in serum FSH was observed after unilateral introvarian P replacement at CLX, even though accompanying patterns of serum estradiol (E2) and P (and the interval to the next LH surge) were not different from those after CLX alone. Our findings indicate that a) P is the principal luteal factor inhibiting new follicle growth, b) P inhibition may be exerted, at least in part, on the ovaries directly, and c) an ovarian factor other than P or E2 may contribute to the regulation of FSH, and perhaps LH, secretion in this primate.