Segmental differentiations of cell junctions in the vascular endothelium. The microvasculature
Segmental differentiations of cell junctions in the vascular endothelium. The microvasculature
复制标题
血管内皮细胞连接的节段分化。
作者：
M. Simionescu;N. Simionescu;G. Palade
在大鼠网膜和肠系膜中发现了由小动脉、毛细血管和新生小静脉（ACV单位）组成的小血管单位。它们被固定在原位和处理的电子显微镜无论是作为整个单位或作为解剖段。对后者的系统检查（在薄切片中，以及在冷冻裂解制备物中）表明，血管内皮的细胞间连接在微血管系统中从一个节段到另一个节段具有特征性变化。在小动脉中，内皮具有连续的和精细的紧密连接，内插有大的间隙连接。毛细血管内皮具有由分支或交错股形成的紧密连接;在该水平不存在间隙连接。细胞周微静脉表现出组织松散的内皮连接，具有不连续的低轮廓脊和凹槽，通常没有颗粒。在这些血管中没有发现缝隙连接。肌性小静脉的内皮具有相同类型的连接（不连续的脊和低轮廓的凹槽）;此外，它显示出比小动脉更小且频率更低的孤立间隙连接。交通连接（macula communicans）一词被提议作为间隙连接的替代品，因为后者一般来说是不合适的，并且在血管内皮的特殊情况下容易混淆。
Small vascular units consisting of an arteriole, its capillaries, and the emerging venule (ACV units) were identified in the rat omentum and mesentery. They were fixed in situ and processed for electron microscopy either as whole units or as dissected segments. Systematic examination of the latter (in thin sections, as well as in freeze- cleaved preparations) showed that the intercellular junctions of the vascular endothelium vary characteristically from one segment to another in the microvasculature. In arterioles, the endothelium has continuous and elaborate tight junctions with interpolated large gap junctions. The capillary endothelium is provided with tight junctions formed by either branching or staggered strands; gap junctions are absent at this level. The pericytic venules exhibit loosely organized endothelial junctions with discontinuous low-profile ridges and grooves, usually devoid of particles. No gap junctions were found in these vessels. The endothelium of muscular venules has the same type of junctions (discontinuous ridges and grooves of low profile); in addition, it displays isolated gap junctions of smaller size and lower frequency than in arterioles. The term communicating junction (macula communicans) is proposed as a substitute for gap junctions, since the latter is inappropriate, in general, and confusing in the special case of the vascular endothelium.