OBJECTIVES: To compare human and mouse ameloblasts and enamel matrix in early stages of differentiation.
METHODS: Incisors were obtained from 19–24-wk-old human fetal cadavers and six-month-old mice, following institutional guidelines. The teeth were either immediately embedded in O.C.T. compound, or embedded in paraffin after demineralization in EDTA. Sections were stained by H&E and Masson's Trichome. Amelogenin, amelotin and Type I collagen were localized by immunohistochemisty.
RESULTS: The morphology of human pre-secretory ameloblasts included tall columnar shaped cells, while mouse pre-secretory ameloblasts were shorter cuboidal shaped cells. Pre-secretory, secretory, transition ameloblasts of human incisors were immunopositive for amelotin. In contrast, in the mouse sections amelotin was localized only in maturation-stage of ameloblasts. Type I collagen was detected in human pre-secretory ameloblasts and in the enamel matrix but not in mouse sections, whereas amelogenin was localized to the developing ameloblasts abd enamel matrix in both human and mouse incisor sections.
CONCLUSION: The morphology of human pre-secretory ameloblasts is markedly different from mice. Amelotin and Type I collagen were present earlier in human enamel development as compared to mice, while amelogenin expression was similar.
Supported by grant #R21DE017910 from NIDCR