EXPRESSION OF THE INTERMEDIATE FILAMENT NESTIN DURING RODENT TOOTH DEVELOPMENT

The developing tooth represents a suitable model for understanding the molecular mechanisms involved in induction, morphogenesis and differe ntiation of organs. It is conceivable that the developmental changes c ould be reflected in the distribution of different cytoskeletal compon ents and in this report we analyze the expression of the intermediate filament nestin during rodent tooth development at the protein and mRN A levels (by immune light and electron microscopy, and by in situ hybr idization). Nestin is expressed at all stages of tooth development, bu t the expression levels increase after birth in both ectodermal and ec tomesenchymal derivatives. The shift in nestin distribution, from the proliferating dental lamina to the dental mesenchyme, indicates that n estin may be involved in inductive phenomena. At early stages of miner alization, nestin is seen within the apical parts of the presecretory ameloblasts. Nestin is also expressed in odontoblasts, both during odo ntogenesis and after tooth eruption. The increase in nestin expression from early to late developmental stages and sustained expression in a differentiated cell type contrasts with previously observed patterns of nestin expression during nerve and muscle development. This suggest s that nestin could be used as a specific marker for the odontoblast.