Heuser's membrane

Heuser's membrane
Days	12
Gives rise to	extraembryonic coelom

Heuser's membrane (or the exocoelomic membrane) is a short lived combination of hypoblast cells and extracellular matrix.

At day 9-10, at the abembryonic pole, cells from the cytotrophoblast flatten to create a thin exocoelomic membrane known as Heuser’s Membrane. It surrounds the exocoelomic cavity.i.e. it lines the inner surface of the cytotrophoblast.

At days 11 to 12, there is further delineation of the trophoblastic cells giving rise to a layer of loosely arranged cells that inserts between Heuser’s membrane and both syncytio and cytotrophoblast.