Umbilical cord these branches joins with the hepatic portal vein (connecting to its left branch), which carries blood into the liver. The second branch (known as the ductus venosus) bypasses the liver and flows into the inferior vena cava, which carries blood towards the heart. The two umbilical arteries branch from the internal iliac arteries and pass on either side of the urinary bladder into the umbilical cord, completing the circuit back to the placenta. In absence of external interventions, the umbilical cord occludes physiologically shortly after birth, explained both by a swelling and collapse of Wharton's jelly in response to a
Studies of the Fetus in the Womb imbricato" ("Ask Biagino Crivelli's wife how the capon rears and hatches the eggs of hens when he is unplucked"). Da Vinci theorized that the umbilical cord was responsible for taking the fetus’ urine outside of the uterus. The studies were initially bequeathed to Francesco Melzi. In c. 1582–90 they were bought from his heirs by Pompeo Leoni and by 1630 they belonged to Thomas Howard, 2nd Earl of Arundel. Since 1690 the studies have been housed in the Royal Collection, United Kingdom. Studies of the Fetus in the Womb Studies of the Fetus in the Womb are two colored annotated