THE CYTOLOGICAL LOCALIZATION OF HUMAN CHORIONIC GONADOTROPIN.

The indirect fluorescent antibody technique was used to determine the cellular site of human chorionic gonadotropin (H.C.G.) in normal and toxaemic placentas, and in choriocarcinomas. In placental tissue specific fluorescence was located in the syncytial cells of the chorionic villi but not in the cytotrophoblast cells. In choriocarcinomas specific fluorescence was seen in the syncytial giant cells. No distinct difference could be demonstrated between normal and "toxic" placentas. Differences in the content of H.C.G. in placentas at various stages of pregnancy were noted. Maximum amounts were demonstrated in tissue of less than 14 weeks gestation. Lesser quantities could be seen in more mature placentas and some specific fluorescence could be seen in most full term placentas.