Cribb A M, Scott J E
Manchester University, UK.
J Anat. 1995 Oct;187 ( Pt 2)(Pt 2):423-8.
Tendons are parallel arrays of collagenous fibres which are specialised to resist and transmit tensile stresses. The response of tendon fibres to tensile stress is age-dependent and complex. Elastic elongation at low stress is accompanied by the disappearance of alternate light and dark bands seen in transmitted polarised light. This region of the stress/strain curve is associated with straightening of fibre 'crimps'. At higher stress, elongation is still elastic and reversible until break point is reached. This behaviour may be associated with straightening of a helical arrangement of collagen fibrils. In addition to the collagen fibrils, there are transverse and longitudinal proteoglycan filaments, many of which bridge and link between the fibrils. We have investigated the effect of various levels of stress from very low up to breaking point on the appearance of the proteoglycan filaments and their relationships with the collagen fibrils. Proteoglycan-collagen fibril interactions in rat and mouse tail and flexor digitorum tendons were visualised by Cupromeronic blue staining, applied to dissected fibres in the resting state and at stresses up to breaking. Proteoglycan filaments were seen to be orthogonally arranged in every D period, probably at the d band in mature tendons. In immature tendons proteoglycan filaments took up more varied orientations, but were mainly orthogonal or axially arranged with respect to the collagen fibrils. Both pictures appeared unchanged after application of stress of any level up to breaking point. Young tendons ruptured at lower stresses than mature tendons. It is suggested that PG bridges between collagen fibrils play a part in transmitting and resisting tensile stresses in tendons, contributing to the strength of the tissue.
肌腱是胶原纤维的平行排列结构，专门用于抵抗和传递拉伸应力。肌腱纤维对拉伸应力的反应取决于年龄且较为复杂。低应力下的弹性伸长伴随着在透射偏振光下可见的明暗交替带的消失。应力/应变曲线的这一区域与纤维“卷曲”的伸直有关。在较高应力下，伸长仍然是弹性的且可逆，直到达到断裂点。这种行为可能与胶原原纤维螺旋排列的伸直有关。除了胶原原纤维外，还有横向和纵向的蛋白聚糖丝，其中许多在原纤维之间架桥并连接。我们研究了从极低到断裂点的各种应力水平对蛋白聚糖丝外观及其与胶原原纤维关系的影响。通过应用铜铬蓝染色，对处于静止状态以及高达断裂应力下的大鼠和小鼠尾巴及指浅屈肌腱的解剖纤维进行观察，从而使蛋白聚糖 - 胶原原纤维相互作用可视化。在每个D周期中，蛋白聚糖丝呈正交排列，可能位于成熟肌腱的d带处。在未成熟肌腱中，蛋白聚糖丝的取向更多样化，但主要相对于胶原原纤维呈正交或轴向排列。在施加高达断裂点的任何应力水平后，这两种情况均未发生变化。年轻肌腱比成熟肌腱在更低应力下断裂。有人提出，胶原原纤维之间的蛋白聚糖桥在肌腱中传递和抵抗拉伸应力方面发挥作用，有助于组织的强度。
