Exomphalos is caused by a failure of the ventral body wall to form and close the naturally occurring umbilical hernia that occurs during embryonic folding which is a process of embryogenesis. The normal process of embryogenesis is that at 2 weeks gestation the human embryo is a flat disc that consists of three layers, the outer ectoderm and inner endoderm separated by a middle layer called the mesoderm. The ectoderm gives rise to skin and the CNS, the mesoderm gives rise to muscle and the endoderm gives rise to organs. The focus areas for exomphalos are that the ectoderm will form the umbilical ring, the mesoderm will form the abdominal muscles and the endoderm will form the gut. After the disc becomes tri-layered, it undergoes growth and folding to transform it from disc to cylinder shaped. The layer of ectoderm and mesoderm in the dorsal axis grow ventrally to meet at the midline. Simultaneously, the cephalic (head) and caudal (tail) ends of these layers of the disc fold ventrally to meet the lateral folds in the center. The meeting of both axis at the center form the umbilical ring. Meanwhile, the endoderm migrates to the center of this cylinder.