DOMON Takanori Hokkaido University, Graduate School of Dental Medicine, Associate Professor, 大学院歯学研究科, 助教授 (50217618)
TAKAHASHI Shigeru Hokkaido University, Graduate School of Dental Medicine, Instructor, 大学院歯学研究科, 助手 (70241338)
|Budget Amount *help
¥2,000,000 (Direct Cost: ¥2,000,000)
Fiscal Year 2006: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fixed, demineralized sections have been generally used for histological and histcochemical studies of the cementum. The fixation and demineralization, however, may cause the structural change and/or loss of matrices. Calcium especially can not be detected in demineralized sections. To overcome the difficulty, unfixed,
undemineralized sections are necessary.
We prepared unfixed, undemineralized frozen sections of rat molars by an adhesive film method, and examined the localization of alkaline phosphatase (ALP) by Azo-dye staining, calcium by glycol bis(2-hydroxyanil)(GBHA) staining, and bone sialoprotein(BSP) and osteopontin(OPN) by immunohistochemistry. We found the following : 1) with the onset of dentin mineralization, the initial acellular cementum appears on the mineralized dentin ; 2) the initial acellular cementum is fibril-poor, and rich in BSP and OPN ; 3) at the initial acellular cementogenesis, cementoblasts show the intense ALP reaction, and small GBHA reactive particles (=cal
cium-GBHA comprex, about 1μm in diameter) appear on the root surface; 4) as principal fibers attach to the initial cementum, the ALP reaction became low and GBHA reactive particles decrease in number.
It has been shown that matrix vesicles and calciferous spherules appear on the root surface at the initial acellular cementogenesis, but after principal fiber attachment, either of the two structures is not seen. From the above findings, we concluded that: 1) at the initial acellular cementogenesis, cementoblasts release matrix vesicles, which result in calciferous spherules corresponding to the GBHA reactive particles; 2) calciferous spherules induce the mineralization of the initial acellular cementum; 3) after principal fiber attachment, the mineralization advances along principal fibers without matrix vesicles. In addition, this study showed that the histochemical and immunohistochemical reactions are preserved better in unfixed, undemineralized sections than in fixed, demineralized sections. Less