title: Development of the ventral body wall in the human embryo.
abstract: Migratory failure of somitic cells is the commonest explanation for ventral body wall defects. However, the embryo increases ~ 25-fold in volume in the period that the ventral body wall forms, so that differential growth may, instead, account for the observed changes in topography. Human embryos between 4 and 10 weeks of development were studied, using amira reconstruction and cinema 4D remodeling software for visualization. Initially, vertebrae and ribs had formed medially, and primordia of sternum and hypaxial flank muscle primordium laterally in the body wall at Carnegie Stage (CS)15 (5.5 weeks). The next week, ribs and muscle primordium expanded in ventrolateral direction only. At CS18 (6.5 weeks), separate intercostal and abdominal wall muscles differentiated, and ribs, sterna, and muscles began to expand ventromedially and caudally, with the bilateral sternal bars fusing in the midline after CS20 (7 weeks) and the rectus muscles reaching the umbilicus at CS23 (8 weeks). The near-constant absolute distance between both rectus muscles and approximately fivefold decline of this distance relative to body circumference between 6 and 10 weeks identified dorsoventral growth in the dorsal body wall as determinant of the 'closure' of the ventral body wall. Concomitant with the straightening of the embryonic body axis after the 6th week, the abdominal muscles expanded ventrally and caudally to form the infraumbilical body wall. Our data, therefore, show that the ventral body wall is formed by differential dorsoventral growth in the dorsal part of the body.
authors.affiliation: Department of Anatomy & Embryology, Maastricht University, Maastricht, The Netherlands.
authors.forename: Hayelom K
authors.initials: HK
authors.lastname: Mekonen
authors.affiliation: Department of Anatomy & Embryology, Maastricht University, Maastricht, The Netherlands.
authors.forename: Jill P J M
authors.initials: JP
authors.lastname: Hikspoors
authors.affiliation: Department of Anatomy & Embryology, Maastricht University, Maastricht, The Netherlands.
authors.forename: Greet
authors.initials: G
authors.lastname: Mommen
authors.affiliation: Department of Anatomy & Embryology, Maastricht University, Maastricht, The Netherlands.
authors.forename: S Eleonore
authors.initials: SE
authors.lastname: Köhler
authors.affiliation: Department of Anatomy & Embryology, Maastricht University, Maastricht, The Netherlands.|Tygat Institute for Liver and Intestinal Research, Academic Medical Center, Amsterdam, The Netherlands.
authors.forename: Wouter H
authors.initials: WH
authors.lastname: Lamers
mesh_terms: D000009:Abdominal Muscles / Q000196:embryology; D034861:Abdominal Wall / Q000196:embryology* / Q000254:growth & development; D006554:Hernia, Umbilical / Q000196:embryology; D006801:Humans; D007366:Intercostal Muscles / Q000196:embryology; D008648:Mesoderm / Q000196:embryology; D012272:Ribs / Q000196:embryology; D013131:Spine / Q000196:embryology; D013249:Sternum / Q000196:embryology
keywords: abdominal muscles; dorsoventral differential growth; infraumbilical body wall; ventral body wall