An immunocytochemical study of fetal cells at the maternal-placental interface using monoclonal antibodies to keratins, vimentin and desmin.

The expression of keratin, vimentin and desmin intermediate filaments by cells in the placenta, amniochorion and placental bed at different stages of pregnancy was studied by use of a panel of monoclonal antibodies. All trophoblast subsets express keratin but not vimentin or desmin intermediate filaments at all stages of pregnancy. Differentiation of the various forms of trophoblast probably does not involve qualitative alterations to the keratin pattern of embryonic trophoblast. Amniotic epithelium co-expressed keratin and variable amounts of vimentin while a subset of fetal mesenchyme cells of the amniochorion and chorionic villi were immunolabelled by antibodies to keratin, to vimentin and to desmin, suggesting simultaneous triple co-expression of three intermediate filaments. This finding suggests the identification of a cell population that is analogous to parietal endoderm in some eutherian animals.