ABSTRACT
Knowing how veins and lymphatics develop provides a basis for understanding their anatomy and helps explain congenital vascular malformations and developmental abnormalities. Vitelline veins take blood from the yolk sac to the embryo and are later modified to become the superior mesenteric and portal veins, liver sinusoids and hepatic veins, and the final segment becomes the supra-hepatic section of the inferior vena cava. The right umbilical vein gradually disappears and the left umbilical vein becomes dominant, only to be obliterated at birth to form the ligamentum teres. The sinus venosus is the final pathway for flow from the vitelline, umbilical, and common cardinal veins before entering the heart. Each lymphatic duct joins the venous system at the junction of the subclavian and internal jugular veins at the base of the neck. Venous plexuses along the ulnar border of the upper limb fuse to form the basilic, axillary then subclavian vein which opens into the internal jugular vein.
