title: The cephalic neural crest exerts a critical effect on forebrain and midbrain development.
abstract: Encephalisation is the most important characteristic in the evolutionary transition leading from protochordates to vertebrates. This event has coincided with the emergence of a transient and pluripotent structure, the neural crest (NC), which is absent in protochordates. In vertebrates, NC provides the rostral cephalic vesicles with skeletal protection and functional vascularization. The surgical extirpation of the cephalic NC, which is responsible for building up the craniofacial skeleton, results in the absence of facial skeleton together with severe defects of preotic brain development, leading to exencephaly. Here, we have analyzed the role of the NC in forebrain and midbrain development. We show that (i) NC cells (NCC) control Fgf8 expression in the anterior neural ridge, which is considered the prosencephalic organizer; (ii) the cephalic NCC are necessary for the closure of the neural tube; and (iii) NCC contribute to the proper patterning of genes that are expressed in the prosencephalic and mesencephalic alar plate. Along with the development of the roof plate, NCC also concur to the patterning of the pallial and subpallial structures. We show that the NC-dependent production of FGF8 in anterior neural ridge is able to restrict Shh expression to the ventral prosencephalon. All together, these findings support the notion that the cephalic NC controls the formation of craniofacial structures and the development of preotic brain.
authors.affiliation: Laboratoire de Développement, Evolution, et Plasticité du Système Nerveux, Institut de Neurobiologie-Alfred Fessard, Avenue de la Terrasse, F-91198 Gif-sur-Yvette, France.
authors.forename: Sophie E
authors.initials: SE
authors.lastname: Creuzet
authors.forename: Salvador
authors.initials: S
authors.lastname: Martinez
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Le Douarin
mesh_terms: D000818:Animals; D019521:Body Patterning; D002642:Chick Embryo; D004625:Embryo, Nonmammalian / Q000033:anatomy & histology / Q000502:physiology; D051524:Fibroblast Growth Factor 8 / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D006257:Head / Q000033:anatomy & histology / Q000196:embryology; D053823:Hedgehog Proteins / Q000235:genetics / Q000378:metabolism; D008636:Mesencephalon / Q000033:anatomy & histology / Q000196:embryology; D009024:Morphogenesis; D009432:Neural Crest / Q000502:physiology*; D020897:Organizers, Embryonic; D016548:Prosencephalon / Q000033:anatomy & histology / Q000196:embryology; D011784:Quail
chemical_list: D053823:Hedgehog Proteins; D051524:Fibroblast Growth Factor 8