The ventral closure of the abdominal wall finally separates the peritoneal cavity from the chorionic cavity. This closure is mainly the result of two developmental processes. The cranial flexion of the embryo leads to the ventral position of the heart and the pericardium. A similar flexion occurs in the caudal part of the embryo, and displaces both the connecting stalk and the allantois in ventral directions. In both cases, the surface ectoderm also is enlarged along with these structures. After closure of the neural tube, the embryo is completely covered with surface ectoderm except at the increasingly narrowing umbilical region (umbilical ring). At the umbilicus, a connection persists for a while between the intra- and extra-embryonic coelom. This connection is called the umbilical coelom. It takes a significant role in the physiological umbilical hernia (physiological umbilical hernia) because the midgut is displaced into this coelom for some weeks. Once the intestinal loops have returned to the abdominal cavity during the early fetal period, the umbilical coelom becomes obliterated and the peritoneal cavity of the fetus is completely separated from the chorionic cavity.