The fine anatomy of the optic nerve of anurans--an electron microscope study.
The fine anatomy of the optic nerve of anurans--an electron microscope study.
复制标题
DOI：
10.1083/jcb.7.1.107
复制
发表时间：
1960-02
期刊：
影响因子：
--
通讯作者：
MATURANA HR
中科院分区：
文献类型：
--
作者：
MATURANA HR
在无尾两栖类的视神经中，许多有髓和无髓轴突在电子显微镜下表现为紧密的束，由一个或几个胶质细胞紧密结合。在这些纤维束中，无髓纤维（直径为0.15至0.6 μ m）比有髓纤维多许多倍，并且通过90至250 A宽的细胞外间隙彼此分离，与周围的神经胶质细胞或相邻的髓鞘分离。该细胞间隙通过到达表面的众多中轴突和细胞边界与神经外围的细胞外间隙连续。大量桥粒加强了相邻胶质细胞膜的附着。有髓鞘的轴突不遵循任何优先路线，并且像无髓鞘的轴突一样，具有弯曲的路径，不断改变它们的相对位置并从一束传递到另一束。在朗维尔氏结，它们与周围细胞的关系完全像无髓鞘轴突。在节间，它们位于无髓轴突之间，与周围的神经胶质细胞没有明显的髓细胞连接。在缺乏结缔组织分离单个有髓纤维和每个胶质细胞同时与许多轴突相关的情况下，这种髓源性连接被其他通过的纤维高度扭曲，并且很难证明。然而，髓鞘层在郎维氏结处的终止方式和髓鞘层的螺旋形分布表明，这些纤维的髓鞘形成是通过类似于周围神经的过程发生的。在有髓视纤维中没有Schmidt-Lantermann切口。
In the optic nerve of Anurans numerous myelinated and unmyelinated axons appear under the electron microscope as compact bundles that are closely bounded by one or several glial cells. In these bundles the unmyelinated fibers (0.15 to 0.6 µ in diameter) are many times more numerous than the myelinated fibers, and are separated from each other, from the bounding glial cells, or from adjacent myelin sheaths, by an extracellular gap that is 90 to 250 A wide. This intercellular space is continuous with the extracellular space in the periphery of the nerve through the numerous mesaxons and cell boundaries which reach the surface. Numerous desmosomes reinforce the attachments of adjacent glial membranes. The myelinated axons do not follow any preferential course and, like the unmyelinated ones, have a sinuous path, continuously shifting their relative position and passing from one bundle to another. At the nodes of Ranvier they behave entirely like unmyelinated axons in their relations to the surrounding cells. At the internodes they lie between the unmyelinated axons without showing an obvious myelogenic connection with the surrounding glial cells. In the absence of connective tissue separating individual myelinated fibers and with each glial cell simultaneously related to many axons, this myelogenic connection is highly distorted by other passing fibers and is very difficult to demonstrate. However, the mode of ending of the myelin layers at the nodes of Ranvier and the spiral disposition of the myelin layers indicate that myelination of these fibers occurs by a process similar to that of peripheral nerves. There are no incisures of Schmidt-Lantermann in the optic myelinated fibers.