Umbilical cord diameter. This diameter decreases rapidly within the placenta. The fully patent umbilical artery has two main layers: an outer layer consisting of circularly arranged smooth muscle cells and an inner layer which shows rather irregularly and loosely arranged cells embedded in abundant ground substance staining metachromatic. The smooth muscle cells of the layer are rather poorly differentiated, contain only a few tiny myofilaments and are thereby unlikely to contribute actively to the process of post-natal closure. The umbilical cord contains Wharton's jelly, a gelatinous substance made largely from mucopolysaccharides which protects the blood vessels inside. It contains one vein, which
Medial umbilical ligament Medial umbilical ligament The medial umbilical ligament (or cord of umbilical artery) is a paired structure found in human anatomy. It is on the deep surface of the anterior abdominal wall, and is covered by the medial umbilical folds ("plicae umbilicales mediales"). It should not be confused with the median umbilical ligament, a different structure that represents the remnant of the embryonic urachus. It represents the remnant of the fetal umbilical arteries, which serves no purpose in humans after birth, except for the initial part that becomes the adult superior vesical artery. It may be used as a landmark for