this term groups together disparate structures with different relationships.

http://upload.wikimedia.org/wikipedia/commons/e/e3/Gray21.png

TODO - consider relationship to UBERON:0000091 ! bilaminar disc

A primary germ layer that can give rise to both mesoderm and endoderm.[AAO], The inner of the two layers of the blastoderm that forms during gastrulation and give rise to the definitive mesoderm and endoderm. Kimmel et al, 1995.[TAO]

uberon

mesendoderm, endomesoderm, future endoderm and mesoderm, hypoblastus

In mammal and avian, extraembryonic endoderm such as visceral endoderm and hypoblast play essential roles in the embryonic axis formation and germ layer development. These extraembryonic tissues are generally considered to have been created in ancestral amniotes evolved from the Xenopus-type ancestor (reference 1); The endomesoderm secretes as yet unidentified signals that posteriorize the ectoderm, which would otherwise adopt an anterior fate. Our results point to a conserved function at the base of deuterostomes for beta-catenin in germ layer specification and to a causal link in the definition of the posterior part of the embryonic ectoderm by way of activating posteriorizing endomesodermal factors (reference 2).[well established][VHOG]

UBERON:0000089

https://github.com/obophenotype/uberon/issues/437

• blastoderm

• axial hypoblast