title: Distinct modes of vertebrate hypaxial muscle formation contribute to the teleost body wall musculature.
abstract: The formation of the body wall musculature in vertebrates is assumed to be initiated by direct ventral extension of the somites/myotomes. This contrasts to the formation of limb muscles and muscles involved in feeding or respiration/ventilation, which are founded by migratory muscle precursors (MMPs) distant to the somites. Here, we present evidence from morphology and expression of molecular markers proposing that the formation of the two muscle layers of the teleost body wall involves both of the above mechanisms: (1) MMPs from somites 5 and 6 found an independent muscle primordium-the so-called posterior hypaxial muscle (PHM)-which subsequently gives rise to the most anterior two segments of the medial obliquus inferioris (OI) muscle. (2) Direct epithelial extension of the hypaxial myotomes generates the OI segments from somite 7 caudalward and the entire lateral obliquus superioris (OS) muscle. The findings are discussed in relation to the evolution of hypaxial myogenic patterning including functional considerations. We hypothesise that the potential of the most anterior somites to generate migratory muscle precursors is a general vertebrate feature that has been differently utilised in the evolution in vertebrate groups.
authors: Division of Zoology, Department of Organismic Biology, University of Salzburg, Austria.
authors: Stefanie E
authors: SE
authors: Windner
authors: Peter
authors: P
authors: Steinbacher
authors: Astrid
authors: A
authors: Obermayer
authors: Barna
authors: B
authors: Kasiba
authors: Josef
authors: J
authors: Zweimueller-Mayer
authors: Walter
authors: W
authors: Stoiber
mesh_terms: D058500:Animal Fins / Q000033:anatomy & histology / Q000196:embryology; D000818:Animals; D019521:Body Patterning / Q000502:physiology; D004625:Embryo, Nonmammalian; D005399:Fishes / Q000033:anatomy & histology / Q000196:embryology*; D007814:Larva; D024510:Muscle Development; D018485:Muscle Fibers, Skeletal; D018482:Muscle, Skeletal / Q000196:embryology*; D018006:Myogenic Regulatory Factors / Q000378:metabolism; D019170:Somites / Q000196:embryology; D014714:Vertebrates / Q000033:anatomy & histology / Q000502:physiology
chemical_list: D018006:Myogenic Regulatory Factors