RT Book, Section A1 Lozada, Jose A1 Stallion, Anthony A2 Usatine, Richard P. A2 Sabella, Camille A2 Smith, Mindy Ann A2 Mayeaux, E.J. A2 Chumley, Heidi S. A2 Appachi, Elumalai SR Print(0) ID 1114873132 T1 Abdominal Wall Defects T2 The Color Atlas of Pediatrics YR 2015 FD 2015 PB McGraw-Hill Education PP New York, NY SN 978-0-07-176701-9 LK accesspediatrics.mhmedical.com/content.aspx?aid=1114873132 RD 2024/03/29 AB The normal abdominal wall is formed by infolding of the cranial, caudal, and two lateral embryonic folds. These folds form in the 4th week of development as a combination of the parietal layer of lateral plate mesoderm and overlying ectoderm. As they move ventrally to meet in the midline, rates of cell proliferation and fusion in the folds differ. This fusion process between the folds is complex, involving cell-to-cell adhesion, cell migration, and cell reorganization. Simultaneously, as the abdominal wall is forming, the rapid growth of the intestinal tract leads to its herniation through the umbilical ring into the yolk sac from the 6th to the 10th week of gestation. By the 10th to 12th week of gestation, the intestine returns to the abdominal cavity in a well-coordinated pattern. This results in normal intestinal rotation and fixation, followed by complete formation of the abdominal wall.1