Source:http://linkedlifedata.com/resource/umls/id/C1281743
MSH: A post-MORULA preimplantation mammalian embryo that develops from a 32-cell stage into a fluid-filled hollow ball of over a hundred cells. A blastocyst has two distinctive tissues. The outer layer of trophoblasts gives rise to extra-embryonic tissues. The inner cell mass gives rise to the embryonic disc and eventual embryo proper.,NCI: An embryo made up of two groups of cells. One group will develop into the fetus and the other will become the placenta.