Direct effect of estradiol-17β on progesterone accumulation by ovarian granulosa cells from rhesus monkeys.

We have previously demonstrated that estradiol-17β (E) administered in vivo induces atresia of the dominant ovarian follicle (DF). Whether this effect is exerted directly at the ovarian level or by central mediation has not been confirmed. The present study was designed to assess whether E in amounts similar to those found in monkey follicular fluid (FF) directly alters in vitro progesterone (P) accumulation by granulosa cells (GC) aspirated from follicles in cycling rhesus monkeys.

Atresia of the dominant ovarian follicle in rhesus monkeys is detected within 24 hours of estradiol treatment.

Following treatment with estradiol-17β (E) on day 6 of the menstrual cycle, degenerative alterations in the microenvironment of the dominant follicle (DF) (follicular fluid [FF], granulosa cells [GC], and oocyte) are readily apparent on day 10, or 96 h after E administration. The present study was designed to determine how early such changes could be detected and which indices of atresia were observed first. The DF was identified during laparoscopy on day 5 or 6 of the cycle, and four capsules containing crystalline E were inserted s.