Throughout intrauterine life, maternal blood supplies the fetus with oxygen and nutrients, and carries away its wastes. The anatomical structures that allow for such an exchange are the umbilical blood vessels. The umbilical vein transports oxygenated blood and nutrients from the placenta to the fetus. The umbilical vein enters the body through the umbilical ring and travels along the anterior abdominal wall to the liver inside the ventral mesentery, which in this region later forms the falciform ligament of the liver. About 50% of the blood it carries passes into the portal venous system of the liver. The remaining 50% enters a vessel called the ductus venosus which bypasses the liver. The ductus venosus travels a short distance and joins the inferior vena cava. There, the oxygenated blood from the placenta is mixed with the deoxygenated blood from the fetal lower extremities, pelvis and kidneys. Inside the ductus...