role of prostaglandins in the mechanisms of ovulation

ABSTRACT

To determine if prostaglandins [PGs] have a direct effect on the ovarian proteolytic enzyme system the ultrastructure of the follicle wall and the microvasculature in the presence and absence of indomethacin were examined. Nine hours after administration of human chorionic gonadotropin [hCH] or hCG plus indomethacin, ovaries were removed and processed for microscopic examination. Also, rabbit ovaries were induced to ovulate with PGF2 [100 ng/ml] in the presence and absence of tranexamic acid [0.1, 1.0 or 10 mM], a plasminogen activator inhibitor. From this study, it was found that the addition of indomethacin to hGG inhibited ovulation and production of PGs without affecting the follicular microvasculature. However, the changes in follicle wall architecture were less pronounced after treatment with indomethacin. Ovulatory efficiency in response to PGF2 2alpha [the percence of follicles >1.5 mm that ovulate] was significantly reduced [P <0.01] by mM tranexamic acid. These results suggest that PGs induce follicular rupture by activation of proteolytic enzymes located in the folicle wall