CD44 is expressed throughout pre-implantation human embryo development.

The cell surface glycoprotein CD44 has been demonstrated in a variety of cell types in embryonic and adult tissues. We have established that CD44 is present on human oocytes, cumulus cells, early embryos and pre-hatched blastocysts by indirect immunofluorescence. We have also shown that CD44 is present on 8-11 week placental stroma cells, but not on the trophoblast. These findings demonstrate that CD44 is present throughout preimplantation development, and that down-regulation occurs on the embryonic surface after implantation.