NCIt definition : Embryonic cells that form the wall of the blastocyst and function to adhere and implant
the embryo into the uterine wall, as well as provide nutrients to the embryo, and
which will eventually give rise to the embryonic part of the placenta.;
Alternative definition : NCI-GLOSS: A thin layer of cells that helps a developing embryo attach to the wall
of the uterus, protects the embryo, and forms a part of the placenta.;