Shivers R R
Cell Tissue Res. 1977 Feb 14;177(4):475-80. doi: 10.1007/BF00220608.
"Tight" or occluding intercellular junctions occur between adjacent glial processes in normal and regenerating crayfish motor nerve sheaths. Although infrequent, these junctions possess the ridge and groove configuration characteristics of freeze-cleaved occluding junctions. When present, nerve sheath tight junctions consist of a single, or at most a few, parallel intramembrane ridges situated on the EF membrane face of the glial plasma membrane. Consequently, such contacts are rarely recognized in thin sections of plastic-embedded nerve sheaths. Crayfish nerve sheath tight junctions are of the fascia occludens type and, therefore, do not impede solute flow across the nerve sheath. Fasciae occludentes of regenerating nerve sheaths occur in close proximity to discoid plaque-like aggregates of particles assumed to represent maculae adhaerentes. This relationship, which was not observed in normal nerve sheaths, suggests a functional association between the two types of junctions, perhaps developmental transformation of one junction type into the other. Although ridges and grooves of tight junctions occur next to cross-fractured trans-glial channels, no functional significance is proposed for this relationship. This study is the first report of tight intercellular junctions in crustacean glial nerve sheaths.
在正常和再生的小龙虾运动神经鞘中，相邻神经胶质细胞突起之间会出现“紧密”或封闭性细胞间连接。尽管这种连接并不常见，但它们具有冷冻蚀刻封闭性连接的嵴和沟结构特征。当存在时，神经鞘紧密连接由位于神经胶质细胞质膜EF膜面上的单个或至多几个平行的膜内嵴组成。因此，在塑料包埋神经鞘的薄切片中很少能识别出这种连接。小龙虾神经鞘紧密连接属于封闭小带类型，因此不会阻碍溶质穿过神经鞘流动。再生神经鞘的封闭小带紧邻假定代表黏着斑的盘状颗粒状聚集体。这种在正常神经鞘中未观察到的关系表明这两种连接类型之间存在功能关联，或许是一种连接类型向另一种连接类型的发育转变。尽管紧密连接的嵴和沟出现在跨神经胶质通道的交叉断裂处旁边，但这种关系的功能意义尚未被提出。本研究是关于甲壳类神经胶质神经鞘中紧密细胞间连接的首次报道。
