Metz J, Forssman W G, Ito S
Cell Tissue Res. 1977 Feb 14;177(4):459-74. doi: 10.1007/BF00220607.
The ultrastructure of the cell membrane and intercellular junctions was studied after isolation of exocrine pancreatic cells by tryptic digestion and mechanical treatment. The number and distribution of membrane associated particles does not change significantly when acinar cells in situ are compared to those after the isolation procedure. However, intercellular junctions undergo distinct alterations. Gap junctions in normal pancreatic cells are macular in shape and localized at the lateral parts of the cell membrane. In isolated acinar cells gap junctions are irregularly shaped, more extended, and frequently associated with tight junctions. Tight junctions form belt-like structures which are found to persist after isolation but subsequently become elongated and interrupted. Thus extensive macular areas of tight junctions develop. Further, the strands on the P-face and the grooves on the E-face of freeze-fracture replicas change in array, dissociate, and become loosely packed on large membrane areas. The present investigation shows that the intramembranous proteins of tight and gap junctions are mobile structures within the fluid membrane. The shape of their array is dependent on the form of the intercellular contact zone.
通过胰蛋白酶消化和机械处理分离外分泌胰腺细胞后，对细胞膜和细胞间连接的超微结构进行了研究。将原位腺泡细胞与分离后的腺泡细胞相比，膜相关颗粒的数量和分布没有明显变化。然而，细胞间连接发生了明显改变。正常胰腺细胞中的缝隙连接呈斑状，位于细胞膜的侧面。在分离的腺泡细胞中，缝隙连接形状不规则，更伸展，且常与紧密连接相关。紧密连接形成带状结构，发现其在分离后持续存在，但随后变长并中断。因此，紧密连接的广泛斑状区域形成。此外，冷冻断裂复制品的P面的条带和E面的凹槽在排列上发生变化，解离，并在大的膜区域松散堆积。本研究表明，紧密连接和缝隙连接的膜内蛋白是流体膜内的可移动结构。它们排列的形状取决于细胞间接触区的形式。
