Flower N E, Filshie B K
J Cell Sci. 1975 Jan;17(1):221-39. doi: 10.1242/jcs.17.1.221.
The junctional structures present between the midgut cells of 3 lepidopteran caterpillars have been examined using freeze-etching, conventional staining and lanthanum tracer techniques. The bonding junction present in this type of tissue is the so-called continuous junction. Septa have only occassionally been reported in conventionally strained cross-sections of these junctions. During the present study septa have been observed in such sections but were more readily located in tissue treated with lanthanum tracer. Tangential sections of lanthanum-impregnated tissue show that these septa are parallel-sided, in contrast to the honeycomb appearance of the septa in septate junctions. The septa in freeze-etch replicas of glutaraldehyde-fixed tissue often show continuous rods on one membrane face, suggesting that the continuous junction may be more akin to the tight junction than to the normal septate junction. However, freeze-etch replicas of unfixed tissue appear much more like replicas of normal septate junctions. The main differences between septate and continuous junctions appear to be that the inter-membrane septa of the continuous junction are parallel-sided in tangential section, as against the honeycomb appearance of the septate junction, and that the particles which delineate the septa in freeze-etched preparations appear to be both somewhat differentl bonded and closer together in the continuous junction. A diagram is presented showing the internal and inter-membrane structures of the 2 types of junction based on the present study, and suggesting a possible explanation of the fact that septa are more readily seen in cross-sections of septate junctions than in continuous junctions. As septa are present in both types of junction, and because their freeze-etch appearances are not very different, it is suggested that the two types of septate junction be called 'smooth septate' and 'pleated septate' junctions, to indicate their characteristic appearances in tangential section.
利用冷冻蚀刻、常规染色和镧示踪技术，对3种鳞翅目毛虫中肠细胞间的连接结构进行了研究。这类组织中存在的结合连接是所谓的连续连接。在这些连接的常规染色横切面上，仅偶尔报道有隔膜。在本研究中，在这类切片中观察到了隔膜，但在用镧示踪剂处理的组织中更容易找到。镧浸渍组织的切向切片显示，这些隔膜的两侧是平行的，这与分隔连接中隔膜的蜂窝状外观形成对比。戊二醛固定组织的冷冻蚀刻复制品中的隔膜在一个膜面上通常显示连续的杆状物，这表明连续连接可能更类似于紧密连接而非正常的分隔连接。然而，未固定组织的冷冻蚀刻复制品看起来更像正常分隔连接的复制品。分隔连接和连续连接之间的主要区别似乎在于，连续连接的膜间隔膜在切向切片中两侧是平行的，而分隔连接的隔膜呈蜂窝状外观，并且在冷冻蚀刻制剂中勾勒隔膜的颗粒在连续连接中似乎结合方式有所不同且靠得更近。根据本研究给出了一个图表，展示了这两种连接的内部和膜间结构，并对在分隔连接的横切面上比在连续连接中更容易看到隔膜这一事实提出了一种可能的解释。由于两种连接中都存在隔膜，并且它们的冷冻蚀刻外观差异不大，因此建议将这两种分隔连接分别称为“平滑分隔”和“褶皱分隔”连接，以表明它们在切向切片中的特征外观。
