Template:Abdominal Wall Muscle Timeline table

From Embryology
Abdominal Wall Muscle Timeline
Carnegie Stage Day Mouse Event
14 33 E10.5 mesoderm of primary body wall non-compact, coalesced in the ventral midline to create the abdominal cavity. Liver and stomach present. Dermomyotomes that are derived from somites have been formed.
16 40 Migration distance about 25% of the hemicircumference of the abdominal cavity. Lateral plate mesoderm has become more condensed and thicker in the area around the myoblasts. Primary abdominal wall ventral to this region was thinner and less dense. Suggests both myoblasts and connective tissue may migrate into the primary body wall or active cell proliferation.
17 42 E11.5 cells now migrated about 50% of the distance to the ventral midline. Inner and outer layers not yet not discernible.
18 44 E12.5 Separation of myoblasts into distinct inner and outer layers. Myoblasts in both inner and outer layers began to exhibit unidirectional orientation. Abdominal wall thicker (500 μm) in region where secondary structures forming compared with primary body wall region (260 μm). More dorsally positioned regions, outermost layer of connective tissue comprised approximately half of this thickness.
19 48 Segregation of the myoblasts into four distinct muscle groups with unidirectional orientation of myoblasts. Myoblasts migrated over half of the distance to the ventral midline. Abdominal wall remains thickest in the area where the muscles migrated and again the outermost layer of connective tissue comprises approximately half of the total thickness of the abdominal wall in this region. Primary abdominal wall that is ventral to the migrating myoblasts noticeably thinner. Human rectus completely separated after migrating over half the distance to the midline. In mouse, the rectus is not segregated from the other muscles until reaching the midline.
21 54 E14.5 Myoblasts have reached the ventral midline and myotubes were present and oriented uniformly within all muscle groups. Rectus abdominis formed distinct bundles of muscle indicating that development and differentiation of this muscle were more prominent in humans than in mice. Connective tissue layers form majority of the thickness of the abdominal wall, outermost layer of connective tissue majority of thickness.
23 58 E15.5 Rectus muscle forms 2 or 3 distinct layers and myotube orientation remained uniform in all muscles. External oblique and internal oblique expand in terms of thickness. Transversus remained a thin layer of muscle. Thickness of the connective tissue was reduced. The orientation of connective tissue layers in the obliques and transversus abdominis was dorsal to ventral.
Table Data[1]
  1. Nichol PF, Corliss RF, Yamada S, Shiota K & Saijoh Y. (2012). Muscle patterning in mouse and human abdominal wall development and omphalocele specimens of humans. Anat Rec (Hoboken) , 295, 2129-40. PMID: 22976993 DOI.