A COMPARATIVE ELECTRON-MICROSCOPIC STUDY OF APATITE CRYSTALS IN COLLAGEN FIBRILS OF RAT BONE, DENTIN AND CALCIFIED TURKEY LEG TENDONS
A COMPARATIVE ELECTRON-MICROSCOPIC STUDY OF APATITE CRYSTALS IN COLLAGEN FIBRILS OF RAT BONE, DENTIN AND CALCIFIED TURKEY LEG TENDONS
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DOI：
10.1016/0169-6009(89)90048-2
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发表时间：
1989-05-01
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影响因子：
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通讯作者：
ARSENAULT, AL
中科院分区：
文献类型：
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作者：
ARSENAULT, AL
用光场电子显微镜研究了大鼠钙化火鸡腿肌腱、皮质骨和牙本质中的晶体-胶原关系。后一种成像技术使特定和直接的可视化磷灰石晶体尺寸及其在胶原纤维中的结晶取向成为可能。皮质骨具有最长的c轴平均长度(170。+-)。50.等)，然后是肌腱(142.+-)。43.ANG.)最小的是牙本质(110.+-)。30.ANG)。在纵向切片的胶原蛋白的轴向周期中，磷灰石的晶向在a、b和c轴面之间交替。磷灰石的这种分布可能反映了晶体与胶原分子的排列，因为它们沿着胶原原纤维的长轴以超螺旋的方式螺旋排列。即使在矿化的早期阶段，磷灰石晶体也定位于胶原纤维的间隙和重叠区。单个胶原期内矿物质的相对含量作为电子吸光度的函数被确定。在肌腱中，矿化开始时，80%的矿物位于缺口带，20%位于重叠带；随着矿化的进一步，这些相对数量变化为缺口带的55%，重叠带的45%。在大量矿化的肌腱中观察到的这个55/45%的比率也在皮质骨和牙本质中观察到。从胶原分子有序性和磷灰石沿胶原纤维扩散的角度讨论了这些发现的意义。
Crystal-collagen relationships in calcified turkey leg tendons and cortical bone and dentin of the rat were studied by bright field electron microscopy. The latter imaging technique enables the specific and direct visualization of apatite crystal sizes and their crystallographic orientations within collagen fibrils. Cortical bone possessed the longest mean c-axial length (170 .+-. 50.ANG.), then the tendon (142 .+-. 43 .ANG.) and the smallest was dentin (110 .+-. 30 .ANG.). Crystallographic orientations of apatite were found to alternate between a,b- and c-axial planes along the axial period of longitudinally sectioned collagen. This distribution of apatite may reflect a crystal alignment with collagen molecules as they spiral in superhelical fashion along the long axis of the collagen fibril. Apatite crystals were localized within both the gap and overlap zones of collagen fibrils even at very early stages of mineralization. The relative amounts of mineral within single collagen periods were determined as a function of electron absorbency. In the tendon at the onset of mineralization 80% of the mineral was located in the gap zone and 20% in the overlap zone; with further mineralization these relative amounts changed to 55% in the gap zone and 45% in the overlap zone. This 55/45% ratio observed in the heavily mineralized tendon was also observed in both cortical bone and dentin. The implications of these findings are discussed in view of collagen molecular ordering and the spread of apatite along collagen fibrils.