Electron Microscopic Study on the Trophoblastic Cell Column of Human Placenta

Abstract

1) Cytotrophoblastic cell column has been studied by light and electron microscopy with the combination of autoradiography and cytochemistry. 2) Autoradiographically, the cytotrophoblastic cell column revealed the most active incorporation of 3H-thymidine, a precursor of DNA, among various regions of the placenta. 3) Morphologically, intermediate cells were frequently observed in various degrees of differentiation, indicating new formation of syncytiotrophoblast which contributed to the elongation of the placental villus. 4) Human chorionic gonadotropin was localized ultrastructurally through the use of peroxidase-labeled anti-HCG method, and the synthesis and secretion of the proteohormone of the placenta were discussed.