Maturation ameloblasts of the porcine tooth germ do not express amelogenin

Amelogenins are the most abundant constituent in the enamel matrix of devel oping teeth. Recent investigations of rodent incisors and molar tooth germs revealed that amelogenins are expressed not only in secretory ameloblasts but also in maturation ameloblasts, although in relatively low levels. In t his study, we investigated expression of amelogenin in the maturation stage of porcine tooth germs by in situ hybridization and immunocytochemistry. A melogenin mRNA was intensely expressed in ameloblasts from the differentiat ion to the transition stages, but was not detected in maturation stage amel oblasts. C-terminal specific anti-amelogenin antiserum, which only reacts w ith nascent amelogenin molecules, stained ameloblasts from the differentiat ion to the transition stages. This antiserum also stained the surface layer of immature enamel at the same stages. At the maturation stage, no immunor eactivity was found within the ameloblasts or the immature enamel. These re sults indicate that, in porcine tooth germs, maturation ameloblasts do not express amelogenins, suggesting that newly secreted enamel matrix proteins from the maturation ameloblast are not essential to enamel maturation occur ring at the maturation stage.