title: Cellular and molecular investigations into the development of the pectoral girdle.
abstract: The forelimbs of higher vertebrates are composed of two portions: the appendicular region (stylopod, zeugopod and autopod) and the less prominent proximal girdle elements (scapula and clavicle) that brace the limb to the main trunk axis. We show that the formation of the muscles of the proximal limb occurs through two distinct mechanisms. The more superficial girdle muscles (pectoral and latissimus dorsi) develop by the "In-Out" mechanism whereby migration of myogenic cells from the somites into the limb bud is followed by their extension from the proximal limb bud out onto the thorax. In contrast, the deeper girdle muscles (e.g. rhomboideus profundus and serratus anterior) are induced by the forelimb field which promotes myotomal extension directly from the somites. Tbx5 inactivation demonstrated its requirement for the development of all forelimb elements which include the skeletal elements, proximal and distal muscles as well as the sternum in mammals and the cleithrum of fish. Intriguingly, the formation of the diaphragm musculature is also dependent on the Tbx5 programme. These observations challenge our classical views of the boundary between limb and trunk tissues. We suggest that significant structures located in the body should be considered as components of the forelimb.
authors: School of Biological Sciences, Institute for Cardiovascular and Metabolic Research, University of Reading, UK. valasekpetr@hotmail.com
authors: Petr
authors: P
authors: Valasek
authors: Susanne
authors: S
authors: Theis
authors: April
authors: A
authors: DeLaurier
authors: Yaniv
authors: Y
authors: Hinits
authors: Graham N
authors: GN
authors: Luke
authors: Anthony M
authors: AM
authors: Otto
authors: James
authors: J
authors: Minchin
authors: Liwen
authors: L
authors: He
authors: Bodo
authors: B
authors: Christ
authors: Gavin
authors: G
authors: Brooks
authors: Helen
authors: H
authors: Sang
authors: Darrell J
authors: DJ
authors: Evans
authors: Malcolm
authors: M
authors: Logan
authors: Ruijin
authors: R
authors: Huang
authors: Ketan
authors: K
authors: Patel
mesh_terms: D000818:Animals; D019521:Body Patterning; D002642:Chick Embryo; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D005552:Forelimb / Q000166:cytology / Q000196:embryology*; D051379:Mice; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000166:cytology / Q000196:embryology*; D019170:Somites / Q000166:cytology; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism; D015027:Zebrafish / Q000196:embryology / Q000235:genetics
chemical_list: D020825:T-Box Domain Proteins; C103172:T-box transcription factor 5