Expression Survey Of Genes Critical For Tooth Development In The Human Embryonic Tooth Germ

In the developing murine tooth, the expression patterns of numerous regulatorygenes have been examined and their roles have begun to be revealed. To unveil themolecular mechanisms that regulate human tooth morphogenesis, we examined theexpression patterns of several regulatory genes, including BMP4, FGF8, MSX1, PAX9,PITX2, and SHOX2, and compared them with that found in mice. All of these genes areknown to play critical roles in murine tooth development. Our resuLts show that thesegenes exhibit basically similar expression patterns in the human tooth germ comparedwith that in the mouse. However, slightly different expression patterns were also observedfor some of the genes at certain stages. For example, MSX1 expression was detected in theinner enamel epithelium in addition to the dental mesenchyme at the bell stage of thehuman tooth. Moreover, FGF8 expression remained in the dental epithelium at the capstage, while PAX9 and SHOX2 expression was detected in both dental epithelium andmesenchyme of the human tooth germ. Our results indicate that, although slightdifferences exist in the gene expression patterns, the human and mouse teeth not onlyshare considerable homology in odontogenesis but also use similar underlying molecularnetworks.