The Purpose of the Umbilical Cord
The umbilical cord is one of the most important things in an unborn baby’s environment. The umbilical cord begins to form between four and six weeks as the embryonic disc takes a cylindrical shape. The proximal portion of the umbilical cord is in the lower third of the embryo, and begins to form and develops a sac. The proximal portion houses the guts until the tenth week of gestation. At this time the umbilical cord is short, usually shorter than the than the head-to-tail length of the embryo. By ten weeks the intestines leave the proximal cord and return to the stomach, the elongation of the cord begins and the location of the umbilicus positions in the middle third of the embryo.
Features
The umbilical cord is a unique tissue covered by a mucoid connective tissue called Wharton’s jelly and a thin mucous membrane. The umbilical cord develops from two separate foetal origins. The yolk sack and the allantoses both compromise the umbilical cords. As a result both are formed from the foetal tissue and can be thought to be part of the foetus. The cord is usually 1-2 cm in diameter and 60 cm long according to Percy Malpas, a British obstetrician who studied cord length in the 1960s.
Wharton’s jelly is a specialized tissue serving many purposes for the developing fetus. Its specialized cells contain gelatin-like mucus that encases fibers. These properties give it elastic and cushion effect, which can tolerate the vibration, bending, stretching and twisting of an active fetus. In addition, it holds the vessels together, may regulate blood flow, plays a role in providing nutrition to the fetus, stores chemistry for the onset of labor, and protects the supply line. Umbilical cords without much Wharton’s jelly are more prone to compression, and complete absence is usually associated with fetal death. If an umbilical cord is twisted or knotted, it is more likely to tighten where there is less resistance, such as an area low in Wharton.s jelly. It is believed that males have more Wharton.s jelly content than do females and that good nutrition increases the amount. Wharton.s jelly tends to reduce with gestational age and can disappear when pregnancies go beyond 40 weeks.
Function
The umbilical cord contains three vessels and two arteries. About 1% of all infants are born with a cord that contains only a single vein and artery. A 15% of these infants are found to have accompanying congenital anomalies, particularly of the kidney and heart.
The umbilical cord has three functions: serves as a blood resource for the foetus, serves as a source of nutrients (calories, proteins, fats and vitamins) and transfers waste products. The umbilical cord carries blood in the opposite direction, from the baby to the placenta. This blood has been emptied of nutrients and oxygen and now carries the fetus’ waste products back to the mother’s bloodstream where she can dispose of them through her system. The blood in the arteries contains waste products, such as carbon dioxide, from the baby’s metabolism. Carbon dioxide is transferred across the placenta to the bloodstream and then into the lungs where it is breathed out. Oxygen is transported from the red blood cells in the circulation across the placenta to the baby in the umbilical vein. In addition to oxygen the umbilical cord transports nutrients from the placenta to the baby.
Umbilical cord problems can be extremely scary to a pregnant woman. According to Dr. Jason H. Collins at The Pregnancy Institute, umbilical cord accidents leading to stillbirth occur in 1.5 of every 1000 births. An otherwise healthy fetus may suddenly develop a problem with the umbilical cord that needs to be carefully watched to make sure it does not develop into an umbilical cord accident.
Sources:
http://www.med.yale.edu/obgyn/kliman/placenta/articles/EOR_UC/Umbilical_Cord.html
https://apps.who.int/rht/documents/MSM98-4/MSM-98-4.htm#IMPORTANCE