Abstract：
Scales are structures composed of mineralized collagen fibrils embedded in the skin of fish. Here we investigate structures contributing to the bulk of the scale material of the sturgeon (Acipencer guldenstatii) at the millimeter, micrometer and nanometer length scales. Polished and fracture surfaces were prepared in each of the three anatomic planes for imaging with light and electron microscopy, as well as focused ion beam - scanning electron microscopy (FIB-SEM). The scale is composed of three layers, upper and lower layers forming the bulk of the scale, as well as a thin surface layer. FTIR shows that the scale is composed mainly of collagen and carbonated hydroxyapatite. Lacunae are present throughout the structure. Fracture surfaces of all three layers are characterized by large diameter collagen fibril bundles (CFBs) emanating from a plane comprising smaller diameter CFBs orientated in different directions. Fine lineations seen in polished surfaces of both major layers are used to define planes called here the striation planes. FIB-SEM image stacks of the upper and lower layers acquired in planes aligned with the striation planes, show that CFBs are oriented in various directions within the striation plane, with larger CFBs emanating from the striation plane. Fibril bundles oriented in different directions in the same plane is reminiscent of a similar organization in orthodentin. The large collagen fibril bundles emanating out of this plane are analogous to von Korff fibrils found in developing dentin with respect to size and orientation. Scales of the sturgeon are unusual in that their mineralized collagen fibril organization contains structural elements of both dentin and bone. The sturgeon scale may be an example of an early evolved mineralized material which is neither bone nor dentin but contains characteristics of both materials, however, the fossil data required to confirm this is missing.
摘要：
鳞片是由嵌入鱼皮中的矿化胶原纤维组成的结构。在这里，我们研究了在毫米处对st鱼（Acipencerguldenstatii）的大部分规模材料做出贡献的结构，微米和纳米长度尺度。在三个解剖平面中的每个平面上准备了抛光表面和断裂表面，以进行光学和电子显微镜成像，以及聚焦离子束扫描电子显微镜（FIB-SEM）。尺度由三层组成，上层和下层形成了大部分的规模，以及一个薄的表面层。FTIR显示水垢主要由胶原和碳酸化羟基磷灰石组成。空隙存在于整个结构中。所有三个层的断裂表面的特征在于大直径胶原原纤维束(CFB)从包含沿不同方向取向的较小直径CFB的平面发出。在两个主要层的抛光表面中看到的细线用于定义这里称为条纹平面的平面。在与条纹平面对齐的平面中获取的上层和下层的FIB-SEM图像堆栈，表明CFB在条纹平面内沿各个方向定向，从条纹平面发出较大的CFB。在同一平面上以不同方向定向的原纤维束让人联想到orthodentin中的类似组织。从该平面发出的大胶原蛋白原纤维束在大小和方向上类似于在牙本质发育中发现的vonKorff原纤维。st鱼的鳞片是不寻常的，因为它们的矿化胶原蛋白原纤维组织包含牙本质和骨骼的结构元素。st鱼规模可能是早期进化的矿化材料的一个例子，该材料既不是骨骼也不是牙质，但包含两种材料的特征。然而,确认这一点所需的化石数据丢失了。
