Immunoreactivity of TRO-tf-01 in chorionic villi of placentae from normal and selected abnormal pregnancies. A) Fetal membranes show very strong expression of transferrin by amniotic epithelium (full arrowhead) and on extravillous cytotrophoblast cells (arrowhead). B) Control experiment without primary antibody shows no transferrin staining in the syncytium of normal term placenta. C) Very low expression of transferrin in the syncytium of normal term placenta. D) Placenta of mother with gestational diabetes shows strong villous expression of transferrin. E) Placenta of mother with pregnancy-induced hypertension shows strong expression of transferrin in villous syncytium. F) Placenta of drug-abuse mother during pregnancy; the transferrin expression is very strong. Hematoxylin counterstained the nuclei.