Regulation of collagenolysis and cell death by plasmin within the formative stigma of preovulatory ovine follicles.

Collagen breakdown and apoptotic cell death within the apex of the preovulatory ovine follicle are characteristic of impending rupture. It has been hypothesized that plasmin regulates these two responses by activating collagenases and tumour necrosis factor alpha (TNF-alpha), respectively. Apical plasmin bioactivity, collagenolysis, TNF-alpha-mediated fragmentation of cellular DNA (a marker of apoptosis), stigma formation, and follicular rupture in sheep were inhibited by intrafollicular injection of alpha 2-antiplasmin. Explants of follicular wall released hydroxyproline-containing peptides (degraded collagen) and bioactive TNF-alpha upon exposure to plasmin. These results indicate that plasmin has an essential intermediary role in the biomechanics of ovulatory ovarian tissue dissolution.