LOCALIZATION OF UROKINASE-TYPE AND TISSUE-TYPE PLASMINOGEN-ACTIVATOR MESSENGER-RNAS IN RAT TESTES

The expressions of urokinase (uPA) and tissue-type plasminogen activat ors (tPA) in different stages of the rat seminiferous epithelial cycle were analyzed by in situ and Northern hybridizations combined with zy mographic analysis. Irradiated rat testes were used to assess the cell localization. Both of the plasminogen activators were expressed in a strictly stage specific manner. Maximal expression of uPA mRNA was see n in Sertoli cells during stages VII-VIII of the cycle. The same expre ssion in the basal compartment of the tubules was detected at 7 days p ost-irradiation (p-i), during a selective reduction of spermatogonia a nd preleptotene spermatocytes. Levels of tPA mRNA started to accumulat e in Sertoli cells at stage VIII and were high during stages IX-XII an d detectable during stages XIII-XIV. At 26 days p-i, reduction of pach ytene spermatocytes, which are shown to be immunoreactive for tPA, did not have an effect on tPA mRNA expression. Catalytic activities of uP A and tPA changed concomitantly to their RNA levels in different stage s of the cycle. However, at 7 days p-i, uPA activity was decreased at stages VII-VIII of the cycle suggesting that germ cell Sertoli cell in teraction is important for uPA activity.