Blastocyst

A preimplantation embryo of 30-150 cells. Contains a layer of specialized cells is made up of trophoblasts, which attach to the uterine wall and form the placenta.  Inside the trophoblast layer is the inner cell mass.  These cells remain undifferentiated.  Embryonic Stem cells are derived from the inner cell mass.

Related Topics:

Genetics

Contributed by: AAAS/DoSER

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