Immunohistochemical localization of fibronectin in the human placentas at their different stages of maturation.

The distribution of fibronectin in the human placenta was studied by the aid of the immunoperoxidase technique using specific antibodies against it. In the early chorionic tissue, fibronectin was distributed along the trophoblastic basement membrane, on the wall of fetal blood vessels, in the connective tissue core, and in the cytotrophoblastic cell columns. In the term placenta, this glycoprotein was detected mainly on the fetal blood vessels and less intensely in the stroma, but not along the trophoblastic basement membrane. Endothelial cells of the blood vessels, fibroblastic cells in the stroma, and unidentified cells in the cytotrophoblastic cell columns were immunostained positively for fibronectin. These data suggest that fibronectin of the placenta is produced locally and retained in the tissue, if not all.