Folding of the embryo

 

The folding of the flat trilaminar embryonic disc into a cylindric embryo establishes the general body form. Folding in the medial plane produces the head and tail folds, and results in the incorporation of part of the yolk sac into the embryo and the formation of the foregut and hindgut. Folding of the embryo in the horizontal plane produces the lateral folds and the formation of the lateral and ventral body walls. Part of the yolk sac is incorporated into the embryo as the midgut.


Folding of the embryo



1. Intermediate mesoderm
2. Yolk sac
3. Gut
4. Intraembryonic coelom
5. Notochord
6. Neural tube