Embryology

Abstract

Umbilical cord or the thread of life is not just a tube or a pipe; it is a unique organ with a complicated architectures and sophisticated structures which enabled it to perform its vital function to supply the fetus with his requirement during the period of pregnancy. The remarkable feature of the umbilical cord that it is devoted of any nerve supply, so the regulation and mediation between the mother and fetus is mainly hormonal; also the umbilical blood vessel are without branches. This is unique compared to the large blood vessels of the adult body, the aorta and vena cava. Umbilical cord properties, therefore, are different in some respects and alike in others. It has two-way traffic: the arteries carry the blood pumped by the heart away from the fetus, and this circulation surrounds the vein normally; the umbilical vein returns blood to the fetus from the placenta rejuvenated with oxygen and nutrients and devoid of waste products. How this happens is still surrounded by mystery. The fetal heart cannot expand or work harder because it is surrounded by a fluid-filled lung, like pushing against a water bed. Therefore, as the fetus steadily grows exponentially and three-dimensionally, how does it accommodate the increased blood volume it needs over time? As the fetus grows, the cord elongates and grows in diameter. The fetus has to work against a larger column of fluid and tissue resistance at the placental end. It has been estimated that by 31 weeks, the umbilical cord must carry 70 quarts of blood per day, moving at 4 miles an hour. This remarkable organ also must participate in fetal growth milestones; additionally, it may act as an assist pump to the fetal heart, which is designed to help the fetus over difficult growth proportions which may exist. The extra stress on the fetus may require that the cord be designed correctly so that it can have properties of an assist mechanism or pump. In order to begin the process of creating solutions to umbilical cord-related complications, understanding cord function and design must be thorough. Throughout human history, stillbirths have been associated with variable umbilical cord anomalies.