Gotow T, Hashimoto P H
J Neurocytol. 1982 Jun;11(3):447-62. doi: 10.1007/BF01257988.
Morphological investigations on the permeability of intercellular junctions between ependymal cells and between capillary endothelial cells in the subcommissural organ (SCO) of the guinea pig have been carried out using freeze-fracturing and tracer experiments with horseradish peroxidase (HRP). The ependymal junction reveals a moderately developed network of tight junctional strands surrounding the tall ependymal cell. The apical portion of this junctional network tends to form nearly complete strands, whereas the basal portion usually shows irregular, fragmented strands often arranged in hairpin-like structures. The passage of intraventricularly infused HRP is blocked, leaving unstained areas, at the level of membrane fusions. At the same time the lateral intercellular space below the junction is densely stained, probably due to invasion from the basal side through adjacent ordinary ependymal junctions. The SCO capillary endothelium shows a high distribution density of pinocytotic vesicles. Vesicular transport of intravascularly injected HRP is observed, but no HRP penetration occurs through the endothelial junction. The active participation of vesicles in tracer movement is shown in preparations fixed before administration of HRP. Extravasation of this tracer is indicated to some degree in the SCO capillary, but permeability here appears to be comparable to that of ordinary brain capillaries. Accordingly, the SCO ependymal tight junction seems to form an effective barrier not to blood plasma or similar materials but to apically secreted substances, preventing them from spreading back into SCO intercellular spaces.
利用冷冻断裂技术以及辣根过氧化物酶（HRP）示踪实验，对豚鼠连合下器官（SCO）室管膜细胞间以及毛细血管内皮细胞间连接的通透性进行了形态学研究。室管膜连接显示出围绕高柱状室管膜细胞的紧密连接链的适度发达网络。该连接网络的顶端部分倾向于形成近乎完整的链，而基部通常显示出不规则的、断裂的链，这些链常排列成发夹状结构。脑室内注入的HRP在膜融合水平处的通过被阻断，留下未染色区域。与此同时，连接下方的细胞间侧间隙被密集染色，这可能是由于从基部通过相邻的普通室管膜连接侵入所致。SCO毛细血管内皮显示出高密度的胞饮小泡分布。观察到血管内注射的HRP的小泡运输，但没有HRP通过内皮连接渗透。在给予HRP之前固定的制剂中显示了小泡在示踪剂移动中的积极参与。在SCO毛细血管中，这种示踪剂有一定程度的外渗，但此处的通透性似乎与普通脑毛细血管相当。因此，SCO室管膜紧密连接似乎形成了一个有效的屏障，不是阻止血浆或类似物质，而是阻止顶端分泌的物质，防止它们扩散回SCO细胞间空间。
