Bone: ultrastructure, mineralogy and chemistry

骨骼是构成我们骨骼的材料，是一种精心设计的材料，由等量的两种成分组成：矿物质和胶原蛋白。这种矿物质由钙盐和磷酸盐的微小晶体组成，这是我们身体中的两种基本化学物质。胶原蛋白是一种蛋白质，是我们体内最丰富的蛋白质，也存在于皮肤和肌腱中。骨骼中的胶原蛋白形成了纤细的“原纤维”，这些纤维捆绑在一起，沿着我们长骨的轴线排列，但是矿物质在哪里呢？以前的研究人员认为它主要在胶原蛋白内部，填充胶原蛋白端到端分子之间的小间隙。然而，我们的研究表明，这种观点是错误的，几乎所有的骨矿物质都是以细长的支柱的形式存在的，这些支柱平行于胶原纤维，并像桶周围的棍棒一样堆叠在它们周围。这些支柱本身是由更小的晶体片组成的，这些晶体片显然是粘在一起制成的。

Bone, the material out of which our bones are constructed, is a finely engineered material made of equal amounts of two components: mineral and collagen. The mineral consists of tiny crystals of a salt of calcium and phosphate, two of the essential chemicals in our body. Collagen is a protein, the most abundant one in our body, also found in skin and tendons. The collagen of bone forms wispy “fibrils” that are bundled together and lined up along the axes of our long bones, but where is the mineral? Previous researchers thought that it was mainly inside the collagen, filling little gaps between end-to-end molecules of collagen. Our research has shown, however, that this view is mistaken, and that almost all the mineral in bone is in the form of slender struts that run parallel to the collagen fibrils and are stacked around them like staves around a barrel. These struts are themselves composed of even smaller crystal flakes that are apparently glued together to make the struts.