The umbilical cord, which grows from the placenta and attaches to the baby at the center of the abdomen, is the source of the baby's nutrition, oxygenation and waste removal. The umbilical cord contains three blood vessels: two arteries and one vein; the blood in all three vessels is fetal blood. Cord blood is sometimes saved and stored because it contains cells that can differentiate into many types of cells.
Anatomy
Umbilical cord blood travels through three vessels from the placenta to the fetus. In the placenta, nutrients are transported across a thin membrane to the umbilical vein, and waste products are transported back to the placenta via the umbilical arteries. The maternal blood vessels and umbilical blood vessels lie very close together, so nutrients and waste can transport easily from one to another. Blood in the umbilical vein travels through the fetus, providing nutrients and oxygenation. Fetal blood depleted of oxygen and nutrients exits out the two umbilical arteries and returns to the placenta.
Umbilical Vein
The umbilical vein carries blood containing 80 percent oxygen from the placenta to the fetus. Umbilical vein blood also contains glucose, vitamins and proteins necessary for fetal growth, according to Human Embryology.
Umbilical Arteries
Fetal blood goes from the baby to the placenta via the umbilical arteries. Cord blood in the arteries is a mixture of arterial and venous blood, which is low in oxygen and contains waste products such as carbon dioxide and urea that would be harmful to the fetus if they built up in the bloodstream, Human Embryology states. In 1 percent of pregnancies, only a single artery develops; fetal abnormalities are more common if this occurs, according to the March of Dimes.
Stem Cell Uses
Cord blood is sometimes saved because it contains stem cells, which are immature cells that can develop into different types of cells, depending on what the body needs. Cells that can differentiate in this way are called multipotent. Stem cells are being used to regenerate damaged tissue and to treat some diseases, such as Type I Diabetes and some kinds of cancers. Stem cells from cord blood are less likely to be rejected than other types of stem cells, the University of Utah states.
Misconceptions
Maternal blood and fetal blood don't freely mix in the umbilical cord or in the placenta. However, a small amount of fetal blood may leak into the maternal blood at the time of delivery. If the maternal and fetal blood types are different, antibodies may develop in the maternal blood that could travel through the placenta and attack the blood of a fetus in a subsequent pregnancy, according to Penn Medicine.
