Canaliculi in the tessellated skeleton of cartilaginous fishes
Canaliculi in the tessellated skeleton of cartilaginous fishes
复制标题
DOI：
10.1111/j.1439-0426.2010.01417.x
复制
发表时间：
2010-04-01
影响因子：
0.9
通讯作者：
Summers, A. P.
中科院分区：
文献类型：
--
作者：
Dean, M. N.;Socha, J. J.;Summers, A. P.
鲨鱼和鳐鱼的内骨骼成分由未钙化的透明软骨状核心组成，其上覆盖着一层薄薄的矿化六角形瓷砖（镶嵌物）纤维陶瓷层，并与镶嵌物间纤维相连。组成组织（未矿化软骨、矿化软骨、纤维组织）的基本空间关系是众所周知的 - 内骨骼镶嵌是长期以来公认的软骨鱼类的同源性 - 但由于样品制备困难以及缺乏足以可视化微观结构和微关联的技术，对它们相互作用的高分辨率和三维（3D）理解受到了阻碍。我们使用冷冻电子显微镜和同步辐射断层扫描来研究棋盘状骨骼的超微结构，但不会损害组成组织之间或棋盘本身的微妙关系。这些技术的结合可以实现以前从未欣赏过的内部结构的可视化，即连接镶嵌物内的空隙空间的通道。这些棋盘内的“小管”将连续的腔隙空间连接成长腔隙串，从镶嵌块的中心向外辐射。整个小管网络中细胞外基质的连续性可能解释了尽管镶嵌在矿物质中，镶嵌物中的软骨细胞仍然保持活力。细胞外液体交换还可以允许软骨细胞之间营养物质以及机械和矿化信号的传递，其方式类似于骨中的小管网络。这些促进细胞外物质交换的共同适应机制表明早期软骨细胞和骨细胞进化具有一定程度的平行性。
P>The endoskeletal elements of sharks and rays are comprised of an uncalcified, hyaline cartilage-like core overlain by a thin fibro-ceramic layer of mineralized hexagonal tiles (tesserae) adjoined by intertesseral fibers. The basic spatial relationships of the constituent tissues (unmineralized cartilage, mineralized cartilage, fibrous tissue) are well-known - endoskeletal tessellation is a long-recognized synapomorphy of elasmobranch fishes - but a high-resolution and three-dimensional (3D) understanding of their interactions has been hampered by difficulties in sample preparation and lack of technologies adequate for visualizing microstructure and microassociations. We used cryo-electron microscopy and synchrotron radiation tomography to investigate tessellated skeleton ultrastructure but without damage to the delicate relationships between constituent tissues or to the tesserae themselves. The combination of these techniques allowed visualization of never before appreciated internal structures, namely passages connecting the lacunar spaces within tesserae. These intratesseral 'canaliculi' link consecutive lacunar spaces into long lacunar strings, radiating outward from the center of tesserae. The continuity of extracellular matrix throughout the canalicular network may explain how chondrocytes in tesserae remain vital despite encasement in mineral. Extracellular fluid exchange may also permit transmission of nutrients, and mechanical and mineralization signals among chondrocytes, in a manner similar to the canalicular network in bone. These co-adapted mechanisms for the facilitated exchange of extracellular material suggest a level of parallelism in early chondrocyte and osteocyte evolution.