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: In the present study, the initial dentine forming areas were stained with ruthenium hexammine trichloride (RHT) and examined under an electron microscope , consequently, the following conclusions were obtained. 1) Basal lamina had a marked affinity for RHT , in particular, and lamina lucida reacted intensely rather than lamina densa.2) The intercellular spaces between preodontoblasts were filled with electron opaque materials which were intensely stained with RHT and appeared almost homogeneous.On the other hand , RHT-positive granules, approximately 30 nm in diameter, from which faint filamentous structures extended radially, were scattered in the predentine matrix. Some of them were situated on the surface of collagen fibrils in the periodic array.3) Large amounts of RHT-positive materials were attached to the outer surface membrane of matrix vesicles.

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Abstract:In the present study,the precipitate formed in situ by the antimonate -osmium mixed fixative was examined using both energy dispersive X-ray microanalysis(EDX)and electron energyloss spectroscopy(EELS)in order to elucidate its chemical composition .EDX spectrum from the antimonate reaction product suggested the presence of complex Ca and Sb .However,since the peaks of Ca and Sb overlap considerably,it was difficult to identify both simultaneously .On the other hand, EELS spectrum clearly indicated the presence of Ca(L2,3,350,346eV)and Sb(M4 ,5,537,528eV)in the electron dense precipitate within secretory granules of preodontoblasts and on the inner face of the plasma membrane of preameloblasts.Thus,EELS analysis is very useful to confirm the presence of Ca and Sb in the antimonate reaction product.