Finlay H M, McCullough L, Canham P B
Department of Medical Biophysics, University of Western Ontario, London, Canada.
J Vasc Res. 1995 Sep-Oct;32(5):301-12. doi: 10.1159/000159104.
Measurements on the directional organization of collagen are necessary for relating the structure and mechanical function of blood vessels. The birefringent optical property of collagen has enabled us to assess the collagen architecture for brain arteries, which are prone to spasm and aneurysm formation. Using the universal stage and polarizing microscope, we measured the three-dimensional organization of the collagen of the main layers of the artery wall, and examined the effect of distending pressure on that organization. Adult arteries obtained from autopsy were fixed at one of three distending pressures, 30, 120 and 200 mm Hg; they were embedded in paraffin and sectioned parallel to the vessel axis at 4 microns thickness. Sections were stained with picrosirius red, a birefringent enhancement stain specific for collagen. Orientation data were obtained from tangential sections from thirteen arteries. We chose to use tangential sections that graze the curving surface of individual layers, to permit measurements that are equally sensitive to fibres in the mechanically meaningful range of directions including longitudinal, helical and circumferential. Each measurement was from a single fibre or group of fibres at a specific location; the mean direction and its variation of alignment within each artery layer were calculated. In some arteries, the adventitia and subendothelium measurements were separated into sublayers, distinguishable by the birefringent optical appearance. Main findings included a substantial component of longitudinal fibres in the adventitia and subendothelium, highly varied in coherence and mean direction, and a thin collagen layer of the adventitia, radially outside the medial muscle cells, that was highly organized circumferentially (circular standard deviation of 9 degrees). At higher pressures, the collagen fabric of all the layers was increasingly coherent and more circumferential in direction.
测量胶原蛋白的定向组织对于了解血管的结构和力学功能至关重要。胶原蛋白的双折射光学特性使我们能够评估脑动脉的胶原蛋白结构，脑动脉容易发生痉挛和形成动脉瘤。我们使用万能载物台和偏振显微镜，测量了动脉壁主要层中胶原蛋白的三维组织，并研究了扩张压力对该组织的影响。从尸检中获取的成年动脉在三种扩张压力（30、120和200毫米汞柱）之一固定；将它们嵌入石蜡中，并沿血管轴平行切成4微米厚的切片。切片用天狼星红染色，天狼星红是一种对胶原蛋白具有特异性的双折射增强染色剂。从13条动脉的切向切片中获取取向数据。我们选择使用掠过各层弯曲表面的切向切片，以便对包括纵向、螺旋状和圆周方向在内的机械意义方向范围内的纤维进行同样敏感的测量。每次测量均来自特定位置的单根纤维或一组纤维；计算每条动脉层内的平均方向及其排列变化。在一些动脉中，外膜和内皮下层的测量被分为可通过双折射光学外观区分的子层。主要发现包括外膜和内皮下层中纵向纤维的大量成分，其连贯性和平均方向变化很大，以及外膜中一层薄的胶原蛋白层，位于内侧肌细胞的径向外侧，其在圆周方向上高度有序（圆形标准差为9度）。在较高压力下，所有层的胶原蛋白结构越来越连贯，方向上越来越呈圆周状。
