In placental mammals, the<unk>  is a tube that connects a developing embryo or fetus to the placenta. It normally contains three vessels, two arteries (Umbilical artery) and one vein (Umbilical vein), buried within Wharton's jelly, for the exchange of nutrient- and oxygen-rich blood between the embryo and placenta. The presence of only two vessels in the cord is sometimes related to abnormalities in the fetus, but may occur without accompanying abnormalities.
Umbilical cord
Cord blood
Abdominal wall
Amniotic sac
Operon
Base of the heart
Umbilical artery
Cloaca 