Plasminogen activator in the rat ovary. Production and gonadotropin regulation of the enzyme in granulosa and thecal cells.

The production of plasminogen activator by ovarian granulosa cells has been previously reported to be temporally correlated with ovulation in the rat and to be under hormonal control of gonadotropins. We have examined the type of plasminogen activator produced by granulosa cells and also investigated other ovarian cell types for synthesis of this enzyme. Using antibodies specific for tissue-type or urokinase-type plasminogen activator, we have found that granulosa cells produce exclusively the tissue-type enzyme. However, in cultures of whole follicles isolated from the ovary, there is primarily synthesis of urokinase-type plasminogen activator. Examination of other isolated ovarian cell types has demonstrated that thecal cells secrete the urokinase-type plasminogen activator and that the production of this enzyme is also regulated by gonadotropins and temporally correlated with ovulation. These results suggest that ovulation requires both types of plasminogen activator and that the neighboring granulosa and thecal cells cooperate to ensure rupture of the follicle wall and unimpeded passage of the ovum into the oviduct.