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[Embryonic odontogenesis in vertebrates. A mini-review].

Although the molecular cascades that control craniofacial development are still largely unknown, the generation of mutant animal models and the identification of gene mutations that cause human craniofacial syndromes have recently given significant insight into how the unique structure of the head develops. Craniofacial structures are formed from the prechordal mesoderm, the craniofacial ectoderm as well as the neural crest cells which develop on the dorsal side of the neural tube. Normal craniofacial morphology as well as normal (in number and in morphology) tooth organs develop as a consequence of complex interactions between these embryonic tissues. A series of inductive and reciprocal signals between the epithelium and mesenchyme determine the growth, the form and the ultimate differentiation of tissues and organs. Genetic research has shown the involvement of numerous developmental genes encoding a variety of transcription factors, growth factors and receptors. Mutations have been associated with, among others, non-syndromal forms of cleft palate, agenesis of tooth organs and abnormalities in the cranial bones.