HUMAN AMELOGENESIS .1. HIGH-RESOLUTION ELECTRON-MICROSCOPY STUDY OF RIBBON-LIKE CRYSTALS
HUMAN AMELOGENESIS .1. HIGH-RESOLUTION ELECTRON-MICROSCOPY STUDY OF RIBBON-LIKE CRYSTALS
复制标题
DOI：
10.1007/bf00334485
复制
发表时间：
1992-10-01
影响因子：
4.2
通讯作者：
FRANK, RM
中科院分区：
文献类型：
--
作者：
CUISINIER, FJG;STEUER, P;FRANK, RM
用高分辨电子显微镜研究了人胎儿牙釉质发育中的带状晶体。这些晶体被经典地描述为在釉质形成过程中形成的第一个有组织的矿物。它们的特点是平均宽厚比（W.T-1）为9.5，40%被弯曲。在点阵图像上，我们注意到与白色斑点相关的中心暗线（CDL）的存在。这两种结构都存在于最小厚度为8-10 nm的晶体中。CDL位于晶体的中心，似乎与初始生长过程有关，但其确切结构和功能尚未完全确定。我们能够研究带状晶体的结构，Scherzer分辨率接近0.2 nm。实验图像与计算机图像吻合良好，表明其结构与羟基磷灰石（HA）有关。此外，离子取代和缺陷的存在也与HA相容。在这项研究中，大约50%的晶体显示出结构缺陷。螺旋位错是最常见的缺陷，并观察到晶体内对齐沿着五个不同的区域轴。还检测到低角度和高角度边界。因此，在晶体中心发现的低角度边界可能与CDLs有关，并与晶体形成的成核步骤有关，而高角度边界可能来自带状晶体的融合。这种机制可以诱导在釉质形成的成熟阶段期间观察到的晶体厚度的生长加速。
Ribbon-like crystals, from developing enamel of human fetuses, were studied by high resolution electron microscopy. These crystals were classically described as the first organized mineral formed during amelogenesis. They were characterized by a mean width-to-thickness ratio (W.T-1) of 9.5, and 40% were bent. On lattice images we noted the presence of the central dark line (CDL) associated with white spots. Both structures were found in crystals with a minimum thickness of 8-10 nm. CDLs were localized in the center of the crystals and seemed to be linked to the initial growth process, but their exact structure and function were not fully determined. We were able to study the structure of the ribbon-like crystals with a Scherzer resolution close to 0.2 nm. The good correspondence between experimental and computed images showed that their structure was related to hydroxyapatite (HA). In addition, the presence of ionic substitutions and deficiencies were also compatible with HA. In this study, about 50% of the crystals showed structural defects. Screw dislocations were the most often noted defects and were observed within crystals aligned along five different zone axes. Low- and high-angle boundaries were also detected. Low-angle boundaries, found in the center of the crystals, could thus be related to CDLs and be implicated in the nucleation step of crystal formation, whereas high-angle boundaries could result from the fusion of ribbon-like crystals. Such mechanisms could induce an acceleration of the growth in thickness of the crystal observed during the maturation stage of amelogenesis.