Localization of ovine placental lactogen in sheep placentomes by electron microscope immunocytochemistry

Ovine placental lactogen immunoreactivity was localized by the indirect immunocytochemical technique using peroxidase-antiperoxidase. The peptide hormone-like material was localized exclusively in the binucleate cell granules and Golgi region in the fetal chorionic epithelium and in granules of similar size and shape scattered throughout the contiguous syncytial layer of placentomes from sheep at 70, 114, 127 and 142 days of pregnancy. This localization supports the suggestion that in the sheep placentome the syncytial layer is formed by migration and fusion of the fetal chorionic binucleate cells.