Return of the intestinal loop to the abdominal coelom after physiological umbilical herniation in the early fetal period.

The intestine elongates during the early fetal period, herniates into the extraembryonic coelom, and subsequently returns to the abdominal coelom. The manner of herniation is well-known; however, the process by which the intestinal loop returns to the abdomen is not clear. Thus, the present study was designed to document and measure intestinal movements in the early fetal period in three dimensions to elucidate the intestinal loop return process.