Localization of plasmin on the surface of the human trophoblast.

: The present study demonstrates the localization of plasmin on the surface of the microvilli of the human placenta using indirect immunofluorescence. This localization might explain why serum levels of fibrin/fibrinogen degradation products are higher in the uterine vein than in the uterine artery. In view of the previous finding of pregnancy zone protein on the trophoblastic surface and the affinity between plasmin and pregnancy zone protein, it is suggested that pregnancy zone protein immobilizes plasmin on the trophoblastic surface.