We examine the structure of the bone of the pharyngeal jaws of a large fish, the black drum (Pogonias cromis), that uses its tooth-jaw complex to crush hard-shelled bivalve mollusks. During mastication huge compressive forces are concentrated in a tiny zone at the tooth-bone interface. We report on the structure of this bone, with emphasis on its contact with the teeth, at different hierarchical levels and in 3D. Micro-CT shows that the molariform teeth do not have roots and are supported by a circular narrow bony rim that surrounds the periphery of the tooth base. The lower pharyngeal jaw is highly porous, as seen by reflected light microscopy and secondary electron microscopy (SE-SEM), with porosity decreasing close to the bone-tooth interface, and back-scattered electron (BSE-SEM) microscopy showing a slight elevation in mineral density. Focused ion beam - scanning electron microscopy (FIB-SEM) in the serial surface view (SSV) mode reveals a most surprising organization at the nanoscale level: parallel arrays of mineralized collagen fibrils surrounding channels of ∼ 100 nm diameter, both with their long axes oriented along the load direction. The channels are filled with organic matter. These fibril-channel arrays are surrounded by a highly disordered mineralized material. This unusual structure clearly functions efficiently under compression, but the precise way by which this unique arrangement achieves this function is unknown.

中文翻译：

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承受异常高机械负荷的鱼咽颚的独特三维结构。

我们检查了一种大鱼的咽颚骨结构，黑鼓（Pogonias cromis）使用其齿颚复合体来压碎硬壳双壳类软体动物。在咀嚼过程中，巨大的压力集中在牙骨界面的一个小区域。我们报告了这种骨骼的结构，重点是它与牙齿的接触，在不同的层次和 3D 中。显微 CT 显示磨牙状牙齿没有牙根，由围绕牙基外围的圆形窄骨缘支撑。下咽颌是高度多孔的，如反射光显微镜和二次电子显微镜 (SE-SEM) 所见，孔隙率在骨牙界面附近减少，背散射电子 (BSE-SEM) 显微镜显示轻微升高在矿物密度。连续表面视图 (SSV) 模式下的聚焦离子束 - 扫描电子显微镜 (FIB-SEM) 揭示了纳米级最令人惊讶的组织：围绕直径约 100 nm 的通道的矿化胶原纤维平行阵列，均具有长轴沿荷载方向。通道充满有机物。这些原纤维通道阵列被高度无序的矿化材料包围。这种不寻常的结构在压缩下显然能有效发挥作用，但这种独特的排列实现这一功能的确切方式尚不清楚。两者的长轴都沿载荷方向定向。通道充满有机物。这些原纤维通道阵列被高度无序的矿化材料包围。这种不寻常的结构在压缩下显然能有效发挥作用，但这种独特的排列实现这一功能的确切方式尚不清楚。两者的长轴都沿载荷方向定向。通道充满有机物质。这些原纤维通道阵列被高度无序的矿化材料包围。这种不寻常的结构在压缩下显然能有效发挥作用，但这种独特的排列实现这一功能的确切方式尚不清楚。