Immunocytochemical Study of the Placenta of a Twin Pregnancy with a Retained Dead Fetus

A placenta of a twin pregnancy with a retained dead fetus (RDFt) was studied im-munohistochemically by comparison with controls consisting of 9 other placentae with a retained dead fetus (RDF) and 20 placentae without an intrauterine fetal death (IUFD) (control placentae without IUFD). By immunohistochemical examination, immunoglobulins were found in villous syncytiotrophoblasts and villous endothelial cells. The positive reactions were, furthermore, diminished by pretreatment with ammonium thiocyanate by immunoelectron microscopy, so that the immunoglobulin binding to chorionic villi were regarded as one of nonspecific bindings. However, a strongly positive immunoreaction for IgG remained in the specimens from the placenta of RDFt after pretreatment with ammonium thiocyanate. The findings indicate that an immunological injury of a placenta is provoked in RDFt.