(or layer of Langhans
) is the inner layer of the trophoblast
, interior to the syncytiotrophoblast
in an embryo. It serves to anchor the embryonic chorion
to the maternal endometrium
Cytotrophoblasts are stem cells in the chorionic villi. During differentiation, mononuclear cytotrophoblast fuse together into the multinucleated syncytiotrophoblasts.
These cells invade maternal uterine tissues and thus are in direct contact with maternal stroma and immune cells.