[Head formation in the vertebrates: facts and hypotheses].
One of the most important features of vertebrates is that, as craniates, they have a head. They present some developmental similarities with the cephalochordates, which constitute a brother group of the vertebrates. The amphioxus has a rudimentary brain vesicle, with a frontal single eye. The vertebrates differ by formation of a "new" skull, largely developed from neural crest and placodic cells. At the light of common literature, we discuss here a possible scenario in which an enlargement of the primary neural induction process gives rise to an extension of the forebrain, followed by increased neural crest cell migration.
Louryan
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Laboratoire d'Anatomie et Embryologie, Faculté Médecine, U.L.B., Bruxelles.
D000818:Animals; D019521:Body Patterning; D006257:Head / Q000196:embryology*; D014714:Vertebrates / Q000196:embryology*