IMMUNOCHEMICAL LOCALIZATION OF INTEGRIN SUBUNITS IN THE HUMAN PLACENTA

Localization of integrins in the human placenta was examined in compar ison with those of fibronectin and laminin. In the early chorionic vil li, the alpha5 and beta1 subunits. were localized on the basal surface of villous cytotrophoblastic cells, while the alpha6 and beta4 subuni ts were distributed around the entire surface of the cytotrophoblastic cells, suggesting that these cells attach to fibronectin rather than laminin on the epithelial basement membrane. In the term placenta, the alpha5 subunit was not detected on the epithelial cells, but the beta 6 and beta4 subunits were detected on the basal surface of syncytiotro phoblastic cells, suggesting that these cells make use of alpha6 beta4 integrin to attach to the trophoblastic basement membrane. These resu lts suggest that cells utilize the specific receptor for their attachm ent in correspondence to the extracellular matrix component to which t hey attach.