Cullen M J
Department of Anatomy and Cell Biology, University of Southern California, School of Medicine, Los Angeles 90033.
J Neurocytol. 1988 Feb;17(1):105-15. doi: 10.1007/BF01735383.
Transection of mouse sciatic nerves produced microscopic changes in the myelin sheaths distal to the transection. Studied with freeze-fracture, these microscopic changes were correlated with alterations in the macromolecular organization of nerve membranes. In control mice, sciatic nerve myelin contained randomly distributed intramembranous particles. In the early stages of myelin breakdown the lamellae split and large areas of myelin membrane lacked intramembranous particles. The remaining particles clustered with a greater than normal density. Degenerating myelin was found within Schwann cells which still had an outer mesaxon and a normal distribution of intramembranous particles on the cell outer membrane. As the degeneration proceeded, myelin ovoids formed which completely lacked intramembranous particles. The findings suggest that during Wallerian degeneration there is a progression of myelin changes leading to the eventual loss of myelin intramembranous particles. These observations are morphological evidence that Schwann cells remove components from selective portions of their membrane during Wallerian degeneration.
切断小鼠坐骨神经会导致切断部位远端的髓鞘出现微观变化。通过冷冻断裂技术研究发现，这些微观变化与神经膜大分子组织的改变相关。在对照小鼠中，坐骨神经髓鞘含有随机分布的膜内颗粒。在髓鞘分解的早期阶段，板层分裂，大片髓鞘膜缺乏膜内颗粒。剩余的颗粒聚集，密度高于正常水平。在仍有外髓鞘系膜且细胞外膜上膜内颗粒分布正常的施万细胞内发现了正在退化的髓鞘。随着退化过程的进行，形成了完全缺乏膜内颗粒的髓鞘卵圆体。这些发现表明，在华勒氏变性过程中，髓鞘变化不断进展，最终导致髓鞘膜内颗粒丢失。这些观察结果是形态学证据，表明施万细胞在华勒氏变性过程中从其膜的选择性部分去除成分。
