title: Specification of the hypaxial musculature.
abstract: During development of the amniote embryo, the dorsolateral territory of the somite is destined to give rise to the hypaxial skeletal musculature. To study the mechanisms that lead to the formation of this musculature, we cloned the chick Lbx1 gene that is specific to prospective hypaxial myoblasts at occipital, cervical and limb levels. Using this gene as a marker, we characterised the anatomical structures that produce the signals necessary for the specification of the hypaxial musculature by ablating them or transplanting them to ectopic locations in the chick embryo. In addition, we inserted BMP4 soaked beads medial to the somite. Our data suggest that lateralising signals from intermediate and lateral mesoderm have to synergise with dorsalising signals from the surface ectoderm to induce the formation of the hypaxial musculature. However, the lateralising function of the lateral mesoderm can only in part be mimicked by BMP4.
authors.affiliation: Department of Developmental Neurobiology, UMDS Guy's Hospital, London Bridge, London SE1 9RT, UK. s.dietrich@umds.ac.uk
authors.forename: S
authors.initials: S
authors.lastname: Dietrich
authors.forename: F R
authors.initials: FR
authors.lastname: Schubert
authors.forename: C
authors.initials: C
authors.lastname: Healy
authors.forename: P T
authors.initials: PT
authors.lastname: Sharpe
authors.forename: A
authors.initials: A
authors.lastname: Lumsden
mesh_terms: D000818:Animals; D030161:Avian Proteins; D001483:Base Sequence; D019521:Body Patterning; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins / Q000378:metabolism; D002490:Central Nervous System / Q000196:embryology; D002642:Chick Embryo; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000235:genetics; D004475:Ectoderm / Q000502:physiology; D018507:Gene Expression Regulation, Developmental; D005801:Genes, Homeobox; D008648:Mesoderm / Q000502:physiology; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000235:genetics*; D018482:Muscle, Skeletal / Q000196:embryology*; D009672:Notochord / Q000196:embryology / Q000637:transplantation; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D016415:Sequence Alignment; D014157:Transcription Factors; D016042:Transplantation, Heterotopic
chemical_list: D030161:Avian Proteins; C525810:Bmp4 protein, mouse; D055415:Bone Morphogenetic Protein 4; D019485:Bone Morphogenetic Proteins; D004268:DNA-Binding Proteins; C113279:LBX1 protein, Gallus gallus; C491868:Lbx1h protein, mouse; D009124:Muscle Proteins; D000072041:PAX3 Transcription Factor; D051761:Paired Box Transcription Factors; D014157:Transcription Factors; C068686:Pax3 protein, mouse