Secretion of plasminogen activator inhibitor type 1 by cultured ovarian cells obtained from gonadotropin-treated immature rats.

It is demonstrated that i) theca-interstitial compartment synthesizes the majority of plasminogen activator inhibitor type 1 (PAI-1) in the ovary before ovulation, and the follicular wall may therefore serve as a specific barrier with the presence of PAI-1 activity to prevent the secretion of tPA into the extrafollicular compartments; ii) granulosa cells secrete only a small amount of ovarian PAI-1, but synthesize the most of tissue-type plasminogen activator tPA involved in the processes leading to ovulation; iii) since only matured cumulus-oocyte complexes secrete a large amount of tPA and PAI-1, both tPA and PAI-1 activity in the conditioned medium may be used as reliable markers for evaluating oocyte quality for in vitro fertilization.