Inner cell mass

Embryoblast (from Greek έμβρυο "seed" and βλαστος "sprout " ) is a technical term from embryogenesis. As embryoblast the part of the blastocyst is referred to, from which the actual embryo develops.

The embryoblast can be in mammals ( with the exception of Ursäuger that no blastocyst and therefore no embryoblast have ) divided by gastrulation in the three germ layers:

• Endoderm
• Mesoderm
• Ectoderm

To differentiate from the embryo Blast is the trophoblast, which is part of the blastocyst, which developed from extraembryonic tissue, such as the fetal membranes and at higher mammals part of the placenta. In humans, the differentiation of the stem cells takes place at about the fourth day of embryonic development in embryoblast and trophoblast.

Embryonic stem cells are obtained from the embryoblast.