Anatomy of the liver The liver is the largest organ in the body, with a weight varying from 1200 to 1600 g. It arises from the foregut endoderm as a diverticulum which extends into the septum transversum and connects with the vitelline veins of the yolk sac. The caudal section of the hepatic anlage ultimately forms the biliary tract and gallbladder while the cephalic section forms the hepatic parenchyma. The vitelline veins form the portal and hepatic veins. The left umbilical vein persists as the ductus venosum and diverts oxygenated blood from the placenta around the liver directly into the inferior vena cava. After birth the vestigial ligamentum venosum runs in the free edge of the falciform ligament (round ligament, ligamentum teres). It may recanalize in patients with portal venous hypertension or can be used after dilatation for exchange blood transfusion or to permit radiological investigation of the portal venous system.