Matus A I, Walters B B, Jones D H
J Neurocytol. 1975 Jun;4(3):357-67. doi: 10.1007/BF01102118.
The ultrastructure of synaptic junctions in whole brain tissue and isolated synaptic membranes has been compared. Type 1 junctions are present in the isolated membranes,readily identified by the presence of dense-staining material associated with the postsynaptic membrane, but the dense projections present at the presynaptic membrane in intact tissue are absent. Type 2 junctions are not easily recognized because of the absence of prominent junctional densities, but apposed membranes with the appearance of type 2 junctions are seen in isolated membrane preparations. Junctions without dense-staining material are also seen among SYNAPtosomes and survive the hypotonic conditions used during isolation of the membranes. It thus seems probable that both type 1 and 2 junctions are present in isolated synaptic membrane preparations. In type 1 junctions after isolation,the postsynaptic thickening and cleft substance are together seen to be composed of an array of 200 A dense-staining subunits spanning the postsynaptic unit membrane. The relationship of this structure to the ultrastructure of the cleft substance and postsynapticthickening in intact tissue is discussed.
对全脑组织和分离出的突触膜中突触连接的超微结构进行了比较。1型连接存在于分离出的膜中，通过与突触后膜相关的深色染色物质的存在很容易识别，但完整组织中突触前膜上存在的致密突起不存在。2型连接由于缺乏明显的连接密度而不易识别，但在分离的膜制剂中可以看到具有2型连接外观的并列膜。在突触小体中也可见没有深色染色物质的连接，并且在膜分离过程中使用的低渗条件下仍能存活。因此，1型和2型连接似乎都存在于分离出的突触膜制剂中。分离后在1型连接中，突触后增厚和裂隙物质一起被视为由一系列跨越突触后单位膜的200埃深色染色亚基组成。讨论了这种结构与完整组织中裂隙物质和突触后增厚的超微结构之间的关系。
