The Early Vascular System:
By 4 weeks of age a comprehensive vascular system is in place (Figure 2.03). Blood returns to the sinus venosus via the common cardinal veins from the embryo, via the umbilical veins from the placenta, and via the vitelline veins from the yolk sac (vitelline vascular plexus).
The pharyngeal arteries of aortic arches 1-6 coming from the right dorsal aorta are seen. These are associated with the early gill pouches. An internal carotid artery supplies the developing brain, and blood vessels carry blood to and from the liver.
Return to Index