And notice we call it a vein and not an artery, because a vein, by definition, always carries blood towards the heart, while the artery always carries blood away from the heart. Now, as it travels past the underdeveloped liver of the fetus, the blood bypasses the liver via blood duct called the ductus Venosis, as shown in this diagram and as shown in this diagram here. So this structure here is our ductus Venosis. It connects the umbilical vein to that inferior Venecaiva and allows the blood to bypass the liver. So the ductus Venosis, that should be Venosis, the ductus Venosis, connects with the inferior Venecaa, which mixes the oxygenated and the deoxygenated blood and the mixed blood. The partially oxygenated blood is shown in light purple and eventually travels to the right atrium of the heart.