BACKGROUND In the microcirculation, red blood cells (RBCs) were observed to be confined to an axial stream surrounded by a marginal RBC depleted layer. This axial accumulation of RBCs is considered to arise from the RBC deformability. OBJECTIVE To quantitatively evaluate the effect of RBC deformability on their axial accumulation at a flow condition comparable to that in arterioles by developing a new observation system for accurate measurements of radial RBC positions in the cross section of capillary tubes. METHODS The cross-sectional distributions of normal and hardened RBCs as well as softened RBCs suspended in capillary tube flows were measured with high spatial resolution. A new observation system was developed in which enface views of the cross-section of the tube were obtained at small distances upstream of the outlet at various longitudinal positions in the tube. RESULTS The radial positions of individual RBCs were detected within 1 μm accuracy. It was found that normal and softened RBCs rapidly migrated away from the wall towards the tube axis, whereas glutaraldehyde-hardened RBCs were dispersed widely over the tube cross-section, depending on the concentration of glutaraldehyde solution. CONCLUSIONS The newly devised observation system revealed quantitatively the essential role of RBC deformability in their axial accumulation.

中文翻译：

---

通过一种新技术确定毛细管中正常和异常红细胞的横截面分布。

背景技术在微循环中，观察到红细胞（RBC）被限制在由边缘RBC耗尽层围绕的轴向流中。RBC的这种轴向积累被认为是由RBC的可变形性引起的。目的通过开发一种新的观察系统来精确测量毛细管横截面中径向红细胞的径向位置，从而定量评估在与小动脉相当的流动条件下红细胞可变形性对其轴向累积的影响。方法以高空间分辨率测量悬浮在毛细管流中的正常和硬化的RBC以及软化的RBC的横截面分布。开发了一种新的观察系统，在该观察系统中，在管子的各个纵向位置上，在出口上游的小距离处可获得管子的横截面视图。结果检测到单个RBC的径向位置精度在1μm以内。发现正常的和软化的RBC迅速从壁向管轴迁移，而戊二醛硬化的RBC根据戊二醛溶液的浓度广泛地分散在管的横截面上。结论新设计的观测系统定量地揭示了RBC变形在其轴向累积中的重要作用。发现正常的和软化的RBC迅速从壁向管轴迁移，而戊二醛硬化的RBC根据戊二醛溶液的浓度广泛地分散在管的横截面上。结论新设计的观测系统定量地揭示了RBC变形在其轴向累积中的重要作用。发现正常的和软化的RBC迅速从壁向管轴迁移，而戊二醛硬化的RBC根据戊二醛溶液的浓度广泛地分散在管的横截面上。结论新设计的观测系统定量地揭示了RBC变形在其轴向累积中的重要作用。