Primitive Cytotrophoblast Cells (ChrF)

Human primitive cytotrophoblast cells give rise to both villous cytotrophoblast cells and primitive syncytiotrophoblast cells. Numerous studies of cell proliferation markers suggest that the ‘stem cell’ at the time of the implanting blastocyst is the cytotrophoblast in the most proximal area of the villi. In the mouse placenta, the closest equivalent to the primitive cytotrophoblast cells are the ectoplacental cone cells, which differentiate to spongioblast cells and to trophoblast giant cells.