MOLECULAR CONTROL OF ODONTOGENIC PATTERNING - POSITIONAL DEPENDENT INITIATION AND MORPHOGENESIS

We have previously proposed that the patterning of the mammalian denti tion is determined by an odontogenic homeobox code, whereby positional specification of odontogenic ectomesenchymal cell populations in a gi ven region of the first branchial arch are determined by the combinati on of different homeobox genes expressed, described in detail in (1). Here we describe the first functional evidence for such a mechanism, a nd show that development of different types of teeth is controlled by independent genetic pathways. We suggest a mechanism whereby patternin g is determined by position dependent control of tooth germ initiation , and propose that the pathway of morphogenesis is directly linked to the early mesenchymal expression of homeobox genes.