Skip Navigation

amnion, amniotic cavity, cut edge of umbilical vesicle, ectoderm, endoderm, extra-embryonic coelom, extra-embryonic mesoblast, mesoderm, umbilical vesicle cavity

A section through the cranial end of the embryonic disc.

Observe:
1. The relation of the three primary germ layers: ectoderm, endoderm and mesoderm.
2. A junction between endodermal and mesodermal cells.
3. The mesodermal layer at the edge of the disc is continuous with extra-embryonic mesoblasts forming the outer layer of the amnion and yolk sac.
4. The convexity of the thick ectodermal layer that forms the floor of the amniotic cavity.
5. The thin endodermal layer that forms the roof of the yolk sac cavity.


Keywords: amnion, amniotic cavity, cut edge of umbilical vesicle, ectoderm, endoderm, extra-embryonic coelom, extra-embryonic mesoblast, mesoderm, umbilical vesicle cavity

Source: Atlas of Human Embryos.