Gene expression of epimorphin in rat incisor ameloblasts.

Epimorphin has been recently identified as an important factor in the morphogenesis of epithelial cells. A cDNA encoding epimorphin from skin of newborn mice was cloned by the polymerase chain-reaction technique before the preparation of digoxigenin-labelled cRNA probes. In situ hybridization of longitudinal sections of rat incisors revealed a distinct pattern of expression of epimorphin mRNA in the ameloblast layer. Epimorphin mRNA was detected from the presecretory stage up to the beginning of the maturation stage of amelogenesis. With the identification of this expression by epithelial-derived cells, i.e. ameloblasts, it is thought likely that epimorphin is one of the factors that modulate the differentiation cascade of ameloblasts in the course of amelogenesis.