The collagen network acts as a scaffold for calcification and its three-dimensional structure influences bone strength. It is therefore important to observe the collagen network in detail and three-dimensionally. In this study, we observed the collagen network of chick embryonic calvaria in membranous bone three-dimensionally by orthogonally arranged FIB-SEM. A 25×25-μm area of chick embryonic calvaria were observed at high resolution (25 nm/pixel). The inside of the bone (i.e. the primary calcified tissue), the bone cells (i.e. the osteoblasts and the osteocytes), the organelles, and the collagen fibrils were observed in detail. These structures were observed three-dimensionally using the Amira software program. In addition, the collagen fibrils of the bone were automatically extracted using the XTracing extension software program, and three-dimensional morphometry was performed. Almost all of the collagen fibrils ran along the longitudinal axis of the trabecular bone. We found that the regularity of the collagen fibril orientation was less remarkable in the osteoblast layer, which contained numerous osteoblasts. The collagen fibril orientation started to show regularity toward the central bone layer, which contained few bone cells.

中文翻译：

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膜性骨中胶原纤维的三维形态学

胶原蛋白网络充当钙化的支架，其三维结构影响骨骼强度。因此，重要的是要详细地和三维地观察胶原蛋白网络。在这项研究中，我们通过正交排列的FIB-SEM三维地观察了膜性骨中鸡胚颅骨的胶原网络。高分辨率（25 nm /像素）观察到鸡胚颅盖面积为25×25-μm。详细观察了骨内部（即主要钙化组织），骨细胞（即成骨细胞和骨细胞），细胞器和胶原纤维。使用Amira软件程序从三维角度观察了这些结构。此外，还可以使用XTracing扩展软件程序自动提取骨骼的胶原纤维，并进行了三维形态测量。几乎所有的胶原原纤维都沿着小梁骨的纵轴排列。我们发现，在含有大量成骨细胞的成骨细胞层中，胶原纤维取向的规律性不太明显。胶原原纤维的取向开始朝着中央骨骼层显示规则性，中央骨骼层包含很少的骨细胞。