Black J A, Waxman S G, Smith M E
J Neuropathol Exp Neurol. 1987 Mar;46(2):167-84. doi: 10.1097/00005072-198703000-00005.
Axonal membrane structure during acute experimental allergic encephalomyelitis (EAE) was examined with freeze-fracture electron microscopy. Axons without myelin sheaths were prevalent within EAE spinal cords. Often these axons were associated with astrocytic processes, though membrane specializations were not observed at these sites. The demyelinated axons exhibited a highly asymmetrical partitioning of intramembranous particles (IMP), with approximately 2,000 particles/micron2 on P-faces and approximately 150/micron2 on E-faces. This distribution and density of IMP is similar to myelinated internodal membrane. The IMP were generally randomly distributed along the axons. However, in some regions, E-faces of demyelinated axons without paranodal-like membrane specialization in the vicinity displayed a greater than normal (approximately 500/micron2) particle density. Many of the IMP in these regions of increased density were of a large (greater than 10 nm) diameter. Axonal membrane bounded by a single set of paranodal oligodendroglial loops ('heminodal') was also observed, and the axolemma adjacent to the terminal glial loop exhibited a gradient of morphologies. The E-faces of presumed heminodal membrane most often displayed a moderately low density of IMP. However, in several instances, heminodal membrane exhibited a moderately high IMP density (approximately 1,100/micron2), similar to that observed within normal nodal membrane. In all cases, a high percentage of the E-face IMP within heminodal membrane were large. The results demonstrate that acute demyelination is associated with a maintenance of the integrity of certain components of the axolemma and an apparent dedifferentiation in other constituents.
采用冷冻断裂电子显微镜检查急性实验性过敏性脑脊髓炎（EAE）期间的轴突膜结构。EAE脊髓内无髓鞘的轴突很常见。这些轴突常与星形胶质细胞突起相关，尽管在这些部位未观察到膜特化。脱髓鞘轴突的膜内颗粒（IMP）呈现高度不对称分布，P面约有2000个颗粒/μm²，E面约有150个颗粒/μm²。IMP的这种分布和密度与有髓神经纤维节间膜相似。IMP通常沿轴突随机分布。然而，在某些区域，附近无节旁样膜特化的脱髓鞘轴突的E面显示出高于正常（约500个颗粒/μm²）的颗粒密度。这些密度增加区域的许多IMP直径较大（大于10nm）。还观察到由单组节旁少突胶质细胞环（“半节点”）界定的轴突膜，与终末胶质环相邻的轴膜表现出形态梯度。推测的半节点膜的E面最常显示IMP密度适中偏低。然而，在一些情况下，半节点膜显示出适中偏高的IMP密度（约1100个颗粒/μm²），与正常节点膜内观察到的相似。在所有情况下，半节点膜内E面IMP的很大比例都很大。结果表明，急性脱髓鞘与轴膜某些成分完整性的维持以及其他成分的明显去分化有关。
