Morphological and Crystallographic Properties of Tooth Enameloid of Medaka (Oryzias latipes)

Tooth enameloid of medaka as a representative of human tooth enamel was analyzed by high-resolution transmission electron microscope (HR-TEM), electron probe microanalyzer (EPMA) and micro-X-ray diffraction to deepen the knowledge on the crystal formation of tooth enamel. HR-TEM observation showed that enameloid crystals, with incomplete slender hexagonal shape, sometimes became fused with each other when the density of crystals increased. EPMA analysis showed clear image maps of calcium, phosphate and iron. The element analysis indicated high concentration of calcium and phosphate. Micro-X-ray diffraction showed that enameloid crystals are composed of relatively well-crystallized hydroxyapatite. Each (211), (112), (210) and (002) reflection peaks was clearly detected. It is suggested that the medaka is useful for research of developing tooth because it is polyphyodont and has a short lifespan.