A quantitative method is described for measuring the amount of plasminogen activator produced by rat ovarian granulosa cells following exposure to hormones in uiuo or in uitro. The results confirm the previously reported observation (Beers, W. H., Strickland, S., and Reich, E. (1975) Cell 6, (387-394) that granulosa cells in uiuo produce increasing amounts of plasminogen activator as the time o...