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Histochemical and Ultrastructural Studies on Relationship between Initial Calcification and Lipids

初始钙化与脂质关系的组织化学和超微结构研究

基本信息

批准号：
05671524
负责人：
TAKAHASHI Tsuneo
金额：
$ 1.34万
依托单位：
Kanagawa Dental College
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1993
资助国家：
日本
起止时间：
1993 至 1995
项目状态：
已结题

项目摘要

This studies aimed at elucidating a biolgical relationship between ossification and lipids in the developmental process of the calvaria of newborn mice at electron microscopic level.Membranous bone tissues (parietal bone) of newborn mice were employed as the material in both in vivo (1-2 days of age) and in vitro (19 days of gestation) experimental systems. The results are as follows.(1) Even in the conventional double fixation method with glutaraldehyde and osmium tetroxide, a rapid dehydration procedure using cold acetone solutions after a perfusion fixation method (adjusted at a given pHin the fixative) made it possible to preserve at a higher frequency the substance which exhibits extracellular multilamellar structures.(2) On the basis of pH experiments for identification and the above findings, it is clear that the main constituents of osteoblastic lipid droplets are not phospholipids or triglycerides. Knowledge obtained strongly suggested that lipid droplets consisted of long-cha … More ined fatty acids.(3) As another component other than fatty acids contained in lipid droplets, the presence of mucopolysaccharides were also detected. There is also the possibility that thesubstance is a protein complex, but the bond with lipids was not thought tobe a strong bond as seen with the liver and intestine. The morphological relationship between above structures and so-called noncollagenous proteins such as osteocalcin orosteopontin etc. is now being studied.(4) With respect to extracellular lipids (in a droplet form) of osteoblasts, it is surmised to be composed of unionized (protonated) fatty acids, while ionized fatty acids-soap surrounds the lipid droplets. It should be emphasized that sudanophilic material (lipid-related sustance) described earlier as a substance observed at initial calcifying sites is likely to be unionized (protonated) fatty acids.(5) Since ionized fatty acids-soap has affinity for calcium, formation of fatty acid-calcium complexes were likely to occur.In conclusion, these results suggest that the presence of exracellular lipid droplets associated with osteoblasts in this study may play an important role in mineralization as a calcium-tapping mechanism, different from the matrix vesicle-associated calcification. Less

本研究旨在从电子显微镜水平上阐明新生小鼠颅骨发育过程中骨化与脂质的生物学关系。以新生小鼠的膜骨组织(顶骨)为材料，在体内(1-2天龄)和体外(妊娠19天)实验系统中进行研究。结果如下：(1)即使在传统的戊二醛和四氧化三铯双重固定法中，灌流固定法(在固定剂中调节一定的pH值)后再用冷丙酮溶液快速脱水，可以较高频率地保存具有细胞外多层结构的物质。(2)根据pH鉴定实验和上述发现，成骨细胞脂滴的主要成分不是磷脂或甘油三酯。已获得的知识有力地表明，脂滴由长链…组成(3)作为脂滴中脂肪酸以外的另一组分，也检测到粘多糖的存在。也有可能这种物质是一种蛋白质复合体，但与脂质的结合并不像与肝脏和肠道那样被认为是强烈的结合。上述结构与骨钙素、骨桥蛋白等所谓的非胶原蛋白之间的形态关系正在研究中。(4)关于成骨细胞的细胞外脂(以液滴的形式)，推测它由离子化(质子化)的脂肪酸组成，而离子化的脂肪酸-肥皂包裹在脂滴周围。应该强调的是，早先被描述为在初始钙化部位观察到的物质(脂相关物质)很可能是离子化(质子化)脂肪酸。(5)由于电离脂肪酸-肥皂对钙具有亲和力，很可能发生脂肪酸-钙复合体的形成。综上所述，这些结果表明，在本研究中，与成骨细胞相关的细胞外脂滴的存在可能作为一种钙分流机制在矿化中发挥重要作用，不同于基质囊泡相关的钙化。较少