Han Sang Kuy, Chen Chao-Wei, Wierwille Jerry, Chen Yu, Hsieh Adam H
Fischell Department of Bioengineering, University of Maryland, College Park, Maryland; Advanced Biomedical and Welfare Technology R&BD group, Korea Institute of Industrial Technology, Cheonan-si, Chungcheongnam-do, Korea.
J Orthop Res. 2015 Mar;33(3):304-11. doi: 10.1002/jor.22778. Epub 2015 Jan 6.
The defining characteristic of the annulus fibrosus (AF) of the intervertebral disc (IVD) has long been the lamellar structures that consist of highly ordered collagen fibers arranged in alternating oblique angles from one layer to the next. However, a series of recent histologic studies have demonstrated that AF lamellae contain elastin- and type VI collagen-rich secondary "cross-bridge" structures across lamellae. In this study, we use optical coherence tomography (OCT) to elucidate the three-dimensional (3-D) morphologies of these translamellar cross-bridges in AF tissues. Mesoscale volumetric images by OCT revealed a 3-D network of heterogeneously distributed cross-bridges. The results of this study confirm the translamellar cross-bridge is identifiable as a distinguishable structure, which lies in the interbundle space of adjacent lamellae and crisscrosses multiple lamellae in the radial direction. In contrast to previously proposed models extrapolated from 2-D sections, results from this current study show that translamellar cross-bridges exist as a complex, interconnected network. We also found much greater variation in lengths of cross-bridges within the interbundle space of lamellae (0.8-1.4 mm from the current study versus 0.3-0.6 mm from 2-D sections). OCT-based 3-D morphology of translamellar cross-bridge provides novel insight into the AF structure.
长期以来，椎间盘（IVD）纤维环（AF）的定义特征一直是层状结构，其由高度有序的胶原纤维组成，这些纤维在相邻层之间以交替的倾斜角度排列。然而，最近一系列组织学研究表明，AF板层包含横跨板层的富含弹性蛋白和VI型胶原的二级“跨桥”结构。在本研究中，我们使用光学相干断层扫描（OCT）来阐明AF组织中这些跨板层跨桥的三维（3-D）形态。OCT获得的中尺度体积图像揭示了跨桥的三维异质分布网络。本研究结果证实，跨板层跨桥可被识别为一种可区分的结构，它位于相邻板层的束间空间内，并在径向上纵横交错多个板层。与先前从二维切片推断出的模型不同，本研究结果表明，跨板层跨桥以复杂的相互连接网络形式存在。我们还发现，板层束间空间内跨桥长度的变化要大得多（本研究为0.8 - 1.4毫米，而二维切片为0.3 - 0.6毫米）。基于OCT的跨板层跨桥三维形态为AF结构提供了新的见解。
