Foetal growth and development is dependent on transport functions of syncytiotrophoblast. The placental transfer involves specific transport mechanisms through both apical (maternal-facing) and basal (foetal-facing) plasma membranes. We have developed strategies to investigate the biophysical characteristics of ionic channels involved in transplacental transport by electrophysiological methods. A useful approach is the transplantation of purified human trophoblast plasma membranes to the membrane of Xenopus oocytes, allowing the study of macroscopic currents. Our previous and present results indicate that injection of apical membrane vesicles bearing ionic channels into Xenopus oocytes results in their functional incorporation. However, we do not have information about the temporal and spatial distribution of proteins after injection. The aim of this study was to explore the structural integration of placental proteins into the oocyte plasma membrane. We correlate oocyte macroscopic currents with immunofluorescent staining with anti human placental alkaline phosphatase monoclonal antibody (anti-hPLAP). Xenopus laevis oocytes were injected with purified apical membrane obtained by differential centrifugations and sucrose gradients. Injected oocytes were fixed in absolute methanol (-20οC) at different times after injection (0-24 h). Non injected and oocytes injected with buffer were used as controls. Paraffin embedded 15μm sections were used for immunofluorescence technique with anti-hPLAP. Control oocytes did not show, neither in plasma membrane nor cytoplasm, a specific labeling. In contrast, an evident peripheral distribution was observed at 16 h post injection in the oocyte plasma membrane domain. Oocytes at initial times (0-8 h) after injection had a cytoplasmatic labeling near the injection site. Currents from injected and non-injected oocytes were monitored by a two-electrode voltage clamp system within 16-24 h post injection. Similar to our previous results (Ivorra et. al, 2002), the elicited macroscopic currents from injected oocytes become larger than those of controls. These results confirm a correlation between electrophysiological findings of placental channels in the oocyte membrane and immunohistochemical follow-up of a specific placental membrane protein. The conclusion from our study is that the channels, already assembled in the syncytiotrophoblast membranes, can be successfully transplanted to the oocyte membrane. This method allows access to the electrophysiological study of human normal and pathological placental transport.