Meller K
Cell Tissue Res. 1985;242(2):289-300. doi: 10.1007/BF00214541.
The ultrastructure of the optic and trigeminal nerves of the rat, cryofixed by use of a liquid nitrogen-propane jet, was examined, paying special attention to the myelin sheath and the cytoskeleton of the axoplasm. The cytoskeleton of the axoplasm is formed by a meshwork of neurofilaments and microtubules connected both to each other and also to the cell organelles and axolemma. These cross-linkers are fixed to the longitudinal neurofilaments in a helical arrangement, which could be a morphological substrate for the diverse axonal transport phenomena. The myelin sheath is formed by concentrically apposed membrane pairs, which are not fused together. The corresponding major and intraperiod lines seen using classical electron microscopy are in fact fissures that are obscured by the pattern of the selective deposition of osmium at certain sites and cannot be interpreted as specific structures. The cryofixed myelin membranes have the appearance of predominantly globular subunits arranged in an asymmetrical bilayer. The globular particles are of diverse diameter and occupy varying positions within the membrane. The tight junctions or zonulae occludentes of the myelin are formed by arrays of isolated particles, and consequently the fibril formation seems to be a result of the chemical fixation.
对使用液氮 - 丙烷喷射冷冻固定的大鼠视神经和三叉神经的超微结构进行了检查，特别关注髓鞘和轴浆的细胞骨架。轴浆的细胞骨架由神经丝和微管的网络构成，它们相互连接，也与细胞器和轴膜相连。这些交联剂以螺旋排列固定在纵向神经丝上，这可能是各种轴突运输现象的形态学基础。髓鞘由同心并置的膜对形成，它们并未融合在一起。使用经典电子显微镜观察到的相应主线条和周期内线实际上是裂缝，这些裂缝被锇在某些部位的选择性沉积模式所掩盖，不能被解释为特定结构。冷冻固定的髓鞘膜主要呈现为不对称双层排列的球状亚基。球状颗粒直径各异，在膜内占据不同位置。髓鞘的紧密连接或闭锁小带由孤立颗粒阵列形成，因此原纤维的形成似乎是化学固定作用的结果。
