Noun
The inner or lower layer of the blastoderm; -- called also endoderm, entoderm, and sometimes hypoderm. See Illust. of Blastoderm, Delamination, and Ectoderm.
Source: Webster's dictionaryAfter that, the epiblast and the hypoblast establish contact with the extraembryonic mesoderm until they cover the yolk sac and amnion. Source: Internet
Some of the migrating cells displace the hypoblast and create the endoderm, and others migrate between the endoderm and the epiblast to create the mesoderm. Source: Internet
This process begins with formation of a primitive streak on the surface of the epiblast. citation The cells of the layers move between the epiblast and hypoblast and begin to spread laterally and cranially. Source: Internet