Lees S, Capel M, Hukins D W, Mook H A
Forsyth Dental Center, 140 Fenway, Boston, Massachusetts 02115, USA.
Calcif Tissue Int. 1997 Jul;61(1):74-6. doi: 10.1007/s002239900298.
Previous studies showed that the equatorial diffraction spacing of the collagen molecules in mineralized tissues decreases when the tissue is dried and that the spacing in totally dried tissue is about the same (1.1 nm) whether mineralized or not. Here we report that spacing decreases were observed in both mineralized and unmineralized turkey leg tendon after soaking in various sodium chloride solutions up to 4.0 M concentration. The effect was seen by X-ray diffraction as well as by neutron diffraction. No effect was seen in turkey leg tendon soaked in 3.0 M ethylene glycol solution. The spacing in unmineralized tissue decreased from 1.459 +/- 0.011 nm in 0.15 M saline to 1.403 +/- 0.025 nm in 1.5 M saline, a change of 0.056 +/- 0.03 nm or 3.84%. In mineralized turkey leg tendon the corresponding spacings were 1.387 +/- 0.012 and 1.321 +/- 0.019 nm, a change of 0.046 +/- 0.02 nm or 3.4%. No significant dimensional change was noted in the thickness even though the equatorial diffraction spacing decreased by 3.4%. Electron microscopy showed the collagen fibrils within the mineralized turkey leg tendon to be surrounded by highly mineralized material. Presumably the composition of the extrafibrillar material is different from the intrafibrillar and therefore the extrafibrillar material is a different kind of composite. If it is assumed that the extrafibrillar material does not change dimensions significantly, then the collagen molecules in the fibrils can be mobile within the dimensionally stable cage-like structure.
先前的研究表明，矿化组织中的胶原分子在组织干燥时赤道衍射间距会减小，并且完全干燥的组织中的间距无论是否矿化都大致相同（1.1纳米）。在此我们报告，在浸泡于浓度高达4.0M的各种氯化钠溶液后，矿化和未矿化的火鸡腿肌腱中均观察到间距减小。通过X射线衍射以及中子衍射都能看到这种效应。浸泡于3.0M乙二醇溶液的火鸡腿肌腱中未观察到效应。未矿化组织中的间距从0.15M盐水中的1.459±0.011纳米减小至1.5M盐水中的1.403±0.025纳米，变化了0.056±0.03纳米，即3.84%。在矿化的火鸡腿肌腱中，相应的间距分别为1.387±0.012纳米和1.321±0.019纳米，变化了0.046±0.02纳米，即3.4%。尽管赤道衍射间距减小了3.4%，但厚度未观察到明显的尺寸变化。电子显微镜显示矿化的火鸡腿肌腱内的胶原纤维被高度矿化的物质所包围。推测纤维外物质的组成与纤维内不同，因此纤维外物质是一种不同类型的复合材料。如果假设纤维外物质的尺寸变化不显著，那么纤维中的胶原分子可以在尺寸稳定的笼状结构内移动。
