Renz H, Schaefer V, Duschner H, Radlanski R J
Freie Universität Berlin, Universitätsklinikum Benjamin Franklin, Germany.
Adv Dent Res. 1997 Nov;11(4):472-7. doi: 10.1177/08959374970110041501.
In ground sections of human teeth, root cementum shows under the light microscope as alternating, almost concentric, dark and light rings. In paleontology and forensic medicine, the number of these incremental lines or annulations is used to derive the age-at-death of the individual. To find the ultrastructural features underlying these cemental annulations, we used bright-field light microscopy (LM), confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and electron-dispersive x-radiation (EDX) in a scanning electron microscope (SEM). Annulations visible in ground sections of about 100-micron thickness were no longer visible in semi-thin sections (thickness, 1-2 microns) of the same specimen in the same area. The assumption that annulations could be caused by super-imposing structures in the depth of field of the light microscope's objective lens was not verified by CLSM. Fiber bundles of higher density than the surrounding matrix in TEM micrographs could not be connected unambiguously with annulations in LM micrographs. After all, the ultrastructural nature of cemental annulations remains an open question.
在人类牙齿的磨片上，在光学显微镜下，牙根牙骨质呈现出交替的、近乎同心的明暗环纹。在古生物学和法医学中，这些增量线或环纹的数量被用来推断个体的死亡年龄。为了找出这些牙骨质环纹背后的超微结构特征，我们在扫描电子显微镜（SEM）中使用了明场光学显微镜（LM）、共聚焦激光扫描显微镜（CLSM）、透射电子显微镜（TEM）和电子色散X射线（EDX）。在约100微米厚的磨片中可见的环纹，在同一标本相同区域的半薄切片（厚度为1 - 2微米）中不再可见。共聚焦激光扫描显微镜并未证实环纹可能是由光学显微镜物镜景深中的叠加结构引起的这一假设。透射电子显微镜照片中密度高于周围基质的纤维束无法与光学显微镜照片中的环纹明确关联。毕竟，牙骨质环纹的超微结构性质仍然是一个悬而未决的问题。
