Use of the Developing Tooth as a Model System in which to Investigate Organogenesis Rozwijający się zawiązek zęba jako model badań organogenezy

Mammalian teeth are formed by a series of reciprocal epithelial−mesenchymal interactions during the odontogenic developmental program, from the early patterning of the future dental axis to the initiation of tooth development at specific sites within the ectoderm. Tooth development is initiated when the mandibular epithelium instructs cranial neural crest−derived ectomesenchymal cells to aggregate at specific sites. In the early embryo, regionally restrict− ed expression of homeobox−containing genes is suggested to be responsible for generating early polarity in the first branchial arch and establishing the molecular foundations for patterning of the skeletal elements. Members of many developmentally−important families of signaling molecules induce early regionally restricted expression of down− stream target genes in the odontogenic ectomesenchyme. Significantly, targeted disruption of a number of these genes and many transcription factors severely disrupt early tooth development. Additionally, several pathways reg− ulating late tooth development have been also recently identified. The following review concentrates on current knowledge about tooth development and describes the so far determined pathways controlling odontogenesi