Blastoderm

A blastoderm (germinal disc, blastodisc) is a single layer of embryonic epithelial tissue that makes up the blastula.

[2]The blastoderm is formed when the oocyte plasma membrane begins cleaving by invagination, creating multiple cells that arrange themselves into an outer sleeve to the blastocoel.

[1] In chicken eggs, the blastoderm represents a flat disc after embryonic fertilization.

[3] At the edge of the blastoderm is the site of active migration by most cells.

[4] DNA repair genes are highly expressed in chicken blastoderms.