Mechanism of controlling blood-cell passage between the sinus endothelial cells

用冷冻断裂法和洗涤剂抽提法对大鼠脾静脉窦内皮细胞间的连接进行了电子显微镜观察。可见粘连和紧密连接。贴壁连接是内皮细胞间的主要连接结构，位于基底面和侧面。在基底外侧贴壁连接处，肌动蛋白细丝与连接膜相连，并与应力纤维中的肌动蛋白细丝连续。在附着点的间隙中存在横桥，桥的间距相当规则。内皮细胞之间也观察到一种紧密连接的形式，闭塞斑点，但并不是在每个细胞结合处都能观察到。电子致密物质在紧密连接的膜的细胞质表面上，将连接膜与大量细丝分开。在基底外侧紧密连接处，肌动蛋白细丝与应力纤维中的肌动蛋白细丝连续。基于这些观察，这两个细胞间连接被认为在窦功能中起重要作用。

Junctions between the sinus endothelial cells of rat spleen were examined by electron microscopy, using both freeze-fracture and detergent-extraction techniques. Adherens and tight junctions were observed. Adherens junctions were the predominant junctional structures between endothelial cells and were located on basolateral and lateral surfaces. At the basolateral adherens junctions, actin filaments were associated with the junctional membrane and were continuous with actin filaments in stress fibers. Cross-bridges were present in the interspaces of the adherens junctions, and spacings of the bridges were fairly regular. A form of tight junction, macula occludens, was also observed between the endothelial cells, it was not observed at every cellular apposition. Electron-dense material, adjoiningthe cytoplasmic surfaces of membranes in the tight junctions, separated the junctional membranes from masses of thin filaments. At basolateral tight junctions, the actin filaments were continuous with those in the stress fibers. Based on these observations, these two intercellular junctions were considered to play important roles in sinus functions.