Cullen M J, de Vries G H, Webster H D
Brain Res. 1981 Dec 21;229(2):311-22. doi: 10.1016/0006-8993(81)90996-3.
The macromolecular organization of membranes isolated from the rabbit optic nerve and tract was analyzed using the freeze-fracture technique. A myelin fraction and two axolemma-enriched fractions were prepared from a preparation of myelinated axons isolated by flotation in a buffered salt-sucrose medium. In the myelinated axon preparation, axolemma and myelin membranes were easily identified. Larger areas of the axon membrane and myelin membrane totally lacked intramembranous particles. The particles remaining on the myelin membrane formed patches of evenly distributed elongated and globular particles. In contrast, the particles remaining on the axolemma were globular in shape and tightly clustered. Particle clustering and particle-free areas were not characteristic of either the axolemma or myelin membrane of whole nerves fixed in situ and processed for freeze-fracture. The isolated myelin membrane fraction contained a large number of vesicles completely lacking intramembranous particles. Of the remaining membrane vesicles, profiles with dispersed elongated and globular particles predominated. A small percentage of vesicles displayed intramembranous particles of the same size, shape and clustering pattern as that seen on the axolemma of the myelinated axon preparation. The two axolemma fractions were enriched in membrane containing tightly clustered globular particles. Particle-free vesicles as well as some myelin membrane vesicles were also seen in the axolemma fractions.
采用冷冻蚀刻技术分析了从兔视神经和视束分离出的膜的大分子结构。通过在缓冲盐 - 蔗糖介质中漂浮分离出有髓轴突制备物，从中制备出一个髓磷脂组分和两个富含轴膜的组分。在有髓轴突制备物中，轴膜和髓磷脂膜很容易识别。轴突膜和髓磷脂膜的较大区域完全没有膜内颗粒。留在髓磷脂膜上的颗粒形成了均匀分布的细长颗粒和球状颗粒的斑块。相比之下，留在轴膜上的颗粒呈球状且紧密聚集。颗粒聚集和无颗粒区域并非原位固定并进行冷冻蚀刻处理的完整神经的轴膜或髓磷脂膜所特有。分离出的髓磷脂膜组分含有大量完全没有膜内颗粒的囊泡。在其余的膜囊泡中，具有分散的细长颗粒和球状颗粒的轮廓占主导。一小部分囊泡显示出与有髓轴突制备物的轴膜上所见相同大小、形状和聚集模式的膜内颗粒。两个轴膜组分富含含有紧密聚集的球状颗粒的膜。在轴膜组分中也可见无颗粒囊泡以及一些髓磷脂膜囊泡。
