The nature and nurture of epithelial-mesenchymal interactions during tooth morphogenesis.

Epithelial-mesenchymal interactions during tooth morphogenesis are inductive and instructive developmental processes as well as permissive and regulatory processes. Data is available to support the early influences of enamel organ epithelium upon a responding mesenchyme in the determination of dental morphogenetic fields (Dryburg, 1967; Miller, 1969). Mesenchymal specificity appears to be operant during tooth shape and form and during the induction of secretary amelogenesis (Kollar, 1972). These heterotypic tissue interactions can be observed in vivo and in vitro. The cellular responses to these interactions appear to be transcriptional, translational and post-translational; as a direct consequence of the interactions, new gene products are synthesized and secreted and/or pre-existing gene products are amplified (Hata and Slavkin, 1978). The mechanism(s) by which epithelial-mesenchymal interactions function may best be learned through critical investigations of differentiation alloantigens, receptors, coupling components within the plasma membrane, translating components by which epigenetic external cues become internal chemical information, and the associations between peripheral and integral proteins within the plasma membrane and intracytoplasmic microfilaments and microtubules.