Electron microscopic study of intercellular canalicular systems in the parietal fetal membranes

An electron microscopic study of the amnion and the chorionic cytotrophoblast has demonstrated the existence of intercellular channels running between the lateral sides of the cells with typical junctional complexes sealing their proximal ends. In the amnion these channels open through the basal lamina into the connective tissue, and in the chorionic cytotrophoblast they open in the direction of the decidua. This situation seems to indicate that fluid emerges from the open mouth of the amniotic intercellular channels and then continues to flow into the channels of the cytotrophoblast, across its podocytic processes, to be discharged into the decidua, and finally drained by maternal decidual vessels. This morphological study suggests that parietal fetal membranes might be an important route for transport of solute and fluid from the amniotic fluid to the maternal circulation.