Definition: 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.
Mammalian only; non-mammalian, use BLASTULA; /transpl: coordinate BLASTOCYST (NIM with no qualifiers) + EMBRYO TRANSFER (IM); do not confuse with BLASTOCYTES see BLASTOMERES
ExamplesBlastocyst Inner Cell Mass; Trophoblasts
