What Is an Umbilical Cord?
An umbilical cord is the essential structure connecting fetus and placenta. It is a conduit for gases and other molecules that are necessary for the baby's growth. The umbilical cord is also a rich reservoir for stem cells, which can be harvested at birth when the umbilical cord is no longer needed for the baby's survival.
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Anatomy
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The umbilical cord is comprised of a core of connective tissue, and two umbilical arteries that twist around the umbilical vein. The outer layer of the cord is sheathed in amniotic membrane.
At the end of gestation, the cord measures about 50 cm in length.
Function
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The umbilical arteries and vein are key to supplying the developing fetus with nutrients and oxygen while allowing for metabolic waste removal.
Fetal lungs are nonfunctional, so gas exchange occurs at the placenta. The umbilical vein carries newly oxygenated blood from the placenta to the fetus. The blood then circulates through the fetal heart where the majority is shunted past the inoperative lungs. The newly deoxygenated blood leaves the heart via the aorta and is carried to the two umbilical arteries. The arteries deliver the blood to the placenta where metabolic wastes are unloaded.
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Features
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The core umbilical tissue is also referred to as Wharton's jelly. It is named after Thomas Wharton (1614 -- 1673), an English anatomist who first detailed its structure. Wharton's jelly is a gelatinous embryonic matrix and therefore rich in undifferentiated cells.
The matrix provides lubrication for the pulsating arteries and veins. Upon delivery, the matrix collapses, occluding the vessels and inhibiting further circulation through the cord.
After Birth
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The umbilical cord is immediately severed upon delivery. The baby retains a small stump attached at the bellybutton and the remaining cord is delivered with the placenta. The baby's stump falls away two to three weeks after birth.
Considerations
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The umbilical cord is a useful resource in stem cell research. It provides an easily obtainable, reliable and inexpensive source of embryonic cells.
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