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

用透射电镜和免疫荧光显微镜观察了大鼠脾窦内皮细胞的微细结构。此外，计算机辅助重建还显示了小管的三维排列，经皂甙提取后，在细胞的基部发现了明显的电子致密的应力纤维，并显示出两种特征性类型和两种类型的混合型。从统计学上看，两种类型的应力纤维的长度有显著差异。磷酸酪氨酸定位于内皮细胞的基底部分和细胞间粘附部位。窦内皮细胞内有两种类型的应力纤维，它们形成一个广泛的网络，窦内皮细胞表面连接的小管系统由细长的小管组成，小管分支、闭合，与质膜相连。它们在细胞器中进进出出，特别是在质膜的球形内陷处紧密排列，同时也沿着它们运行。从计算机辅助重建的小管，这是从质膜的各个部位内陷，被发现是相互连续的，并穿透窦内皮细胞，同时也分支和扩张，形成一个复杂的网络中的细胞质。然而，目前尚不清楚脾窦内皮细胞表面连接小管系统的网络是否具有任何生理意义。

Fine structure of sinus endothelial cells in the rat spleen were examined by transmission electron microscopy and immunofluorescence microscopy. In addition, the three dimensional arrangement of the canaliculi was also demonstrated by computer-aided reconstruction.After extraction with saponin, the stress fibers were found to be conspicuously electron-dense in the basal portion of the cells and demonstrated two characteristic types and the mixed type of these. Statistically, the lengths of two types of stress fibers are significantly different. Phosphotyrosine is localized in the basal part and at the intercellular adhesion site of the endothelial cells. Two types of stress fibers were organized in the sinus endothelial cells and they form a wide-spread network.The surface connected canalicular system of the sinus endothelial cells consisted of slender canaliculi which were branched, anastomosed, and showed continuity with the plasma membrane. They twisted in and out among the organelles and were particularly found in close apposition to the spherical invaginations of the plasma membrane while also running along them. From a computer-aided reconstruction the canaliculi, which were invaginated from various sites of the plasma membrane, were found to be continuous with each other and penetrate the sinus endothelial cell, while also branching and anastomsing to form a complex network in the cytoplasm. However, it is unclear at present as to whether or not the network of the surface connected canalicular system in the splenic sinus endothelial cells has any physiological significance.