Vitelline circulation refers to the system of

blood Blood is a body fluid in the circulatory system of humans and other vertebrates that delivers necessary substances such as nutrients and oxygen to the cells, and transports metabolic waste products away from those same cells. Blood is com ...

flowing from the

embryo An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sp ...

to the yolk sac and back again. The yolk-sac is situated on the ventral aspect of the embryo; it is lined by endoderm, outside of which is a layer of

mesoderm The mesoderm is the middle layer of the three germ layers that develops during gastrulation in the very early development of the embryo of most animals. The outer layer is the ectoderm, and the inner layer is the endoderm.Langman's Medical ...

. It is filled with fluid, the vitelline fluid, which is utilized for the nourishment of the embryo during the earlier stages of its existence. Blood is conveyed to the wall of the sac by the

vitelline arteries The vitelline arteries are the arterial counterpart to the vitelline veins. Like the veins, they play an important role in the vitelline circulation of blood to and from the yolk sac of a fetus. They are a branch of the dorsal aorta. They give ...

(a branch of the dorsal aorta), and after circulating through a wide-meshed capillary plexus, is returned by the

vitelline veins The vitelline veins are veins that drain blood from the yolk sac and the gut tube during gestation. Path They run upward at first in front, and subsequently on either side of the intestinal canal. They unite on the ventral aspect of the canal ...

to the tubular heart of the embryo. This constitutes the vitelline circulation, and by means of it nutritive material is absorbed from the yolk-sac and conveyed to the embryo.

References

External links

*
Overview of three circulation systems
Embryology of cardiovascular system {{circulatory-stub