Body-stalk

Body-stalk
Diagram showing the expansion of amnion and delimitation of the umbilical cord
Section through the embryo
Details
Latin	Pedunculus truncalis
Dorlands /Elsevier	s_21/12755040
Anatomical terminology []

The body-stalk, also known as the allantoic stalk, is a band of mesoderm that connects the caudal end of the embryo to the chorion in development. With the formation of the caudal fold, the body-stalk assumes a ventral position; a diverticulum of the yolk-sac extends into the tail fold and is termed the hind-gut. With continued development, the body-stalk is later replaced by the umbilical cord.

Body stalk anomaly occurs in approximately 1 in 15,000 births. It is a result of defects in the formation of cephalic, caudal, and lateral embryonic body folds.

Human embryo—length, 2 mm. Dorsal view, with the amnion laid open. X 30.

Human embryo of 2.6 mm.

Diagram showing later stage of allantoic development with commencing constriction of the yolk-sac.

Model of human embryo 1.3 mm. long.

Section through ovum imbedded in the uterine decidua.

Embryo between eighteen and twenty-one days.

Human embryo about fifteen days old. Brain and heart represented from right side. Digestive tube and yolk sac in median section.