Extraembryonic Mesoderm

Some articles on extraembryonic, extraembryonic mesoderm:

Extra-embryonic Coelom
... The extraembryonic coelom (or Chorionic cavity) is a portion of the conceptus consisting of a cavity between Heuser's membrane and the Trophoblast ... cells that fill the space between Heuser's membrane and the Trophoblast, forming the extraembryonic mesoderm ... As development progresses, small lacunae begin to form within the extraembryonic mesoderm which become larger and form the extraembryonic coelom ...
Bilaminar Blastocyst - Formation of The Yolk Sac and Chorionic Cavity
... While the primary yolk sac is forming, extraembryonic mesoderm makes its way into the blastocyst cavity to fill it with loosely packed cells ... When the extraembryonic mesoderm is separated into two portions, a new gap arises called the chorionic cavity, or the extra-embryonic coelom ... When the extraembryonic mesoderm splits into two layers, the amnion, yolk sac, and chorion follow its lead and also become double layered ...