The extraembryonic mesoderm supports the epithelium of the amnion and yolk sac as well as the villi, which arise from the trophoblastic tissue. It also is involved in the development of the fetal blood. The extraembryonic mesoderm of the chorion, chorionic villi, and body stalk originates in the caudal margin of the primitive streak which develops in 12- to 14-day human and macaque embryos.
Develops on day 8 in humans. On day 12 of human development, the extraembryonic mesoderm splits to form the chorionic cavity.
Multiple AncestorsSingle AncestorNo DescendantsDevelops fromPart of Parent