Syncytiotrophoblasts are multinucleated cells found in the placenta of human embryos.
They are the outer syncytial layer of the trophoblasts and actively invade the uterine wall.
They form the outermost fetal component of the placenta (also known as 'syntrophoblast') and massively increase the surface area available for nutrient exchange between the mother and the fetus.
Cells from the syncytiotrophoblast secrete human chorionic gonadotropin.
Section through embryonic area of Vespertilio murinus to show the formation of the amniotic cavity.