Progressive remodeling of the oligodendrocyte process arbor during myelinogenesis
Progressive remodeling of the oligodendrocyte process arbor during myelinogenesis
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DOI：
10.1159/000111414
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发表时间：
1996-07-01
影响因子：
2.9
通讯作者：
Friedrich, VL
中科院分区：
文献类型：
--
作者：
Hardy, RJ;Friedrich, VL
髓鞘在中枢神经系统（CNS）中发育，作为少突胶质细胞的过程的精细化。虽然从薄切片电子显微镜研究中了解了少突胶质细胞围绕轴突的螺旋缠绕过程及其随后转化为髓鞘的许多细节，但对髓鞘形成细胞的三维结构还不完全了解。为了表征这方面的少突胶质细胞的发展，我们标记厚（100- 300 μ m）部分的发展中小鼠中枢神经系统与少突胶质细胞标记抗体，记录单个细胞在连续的光学切片共聚焦显微镜，并创建全细胞重建的少突胶质细胞之前和髓鞘形成过程中开始。我们区分了少突胶质细胞成熟的三个阶段，在所有三个阶段都被O 4、O 1和Ranscht单克隆抗体以及针对髓鞘特异性蛋白CNP和髓鞘碱性蛋白的抗体标记。在轴突鞘化开始之前存在的髓鞘前少突胶质细胞发出多个具有主导径向取向的不规则突起，这些突起，其通常终止于细胞体的50 μ m内，具有细胞体本身的3-8倍或更大的表面积，并且可以代表用于对每个细胞的局部环境进行取样和用于识别靶轴突的机制。移行细胞已经开始形成一个或多个髓鞘;这些细胞随着髓鞘节间数量的增加而逐渐减少其放射状突起的数量。每个移行细胞的放射状突起在鞘化开始的突起乔木的部分中减少最多，表明放射状突起的精细化或稳定性的方向控制。成熟的含髓鞘少突胶质细胞完全缺乏放射状突起，而是发出一些稀疏的分支突起，将细胞体与髓鞘节间连接起来。髓鞘形成的最早阶段的三维分析揭示了两个不同的阶段，髓鞘节间形成的起始事件是薄的无分支过程的生长，称为“起始过程”，沿着轴突。第二阶段，螺旋ensheathment的目标轴突，开始通过精心制作从每个启动过程的板层延伸，周向延伸的目标轴突，从而形成其髓鞘的第一个转弯。
Myelin sheaths develop in the central nervous system (CNS) as elaborations of the processes of oligodendrocytes. Although many details of the spiral wrapping of oligodendrocyte processes around axons and their subsequent transformation into myelin sheaths are known from thin-section electron-microscopic studies, the three-dimensional architecture of the myelin-forming cells is incompletely understood. To characterize this aspect of oligodendrocyte development, we labeled thick (100- to 300-mu m) sections of developing murine CNS with oligodendrocyte marker antibodies, recorded individual cells in serial optical sections by confocal microscopy, and created whole-cell reconstructions of oligodendrocytes before and during the initiation of myelination. We distinguish three stages in the maturation of oligodendrocytes, which at all three stages are labeled by the O4, O1 and Ranscht monoclonals and by antibodies against the myelin-specific proteins CNP and myelin basic protein, Premyelinating oligodendrocytes, present before axonal ensheathment begins, emit multiple irregular processes which have predominant radial orientation, These processes, which generally terminate within 50 mu m of the cell body, have a surface area 3-8 times or more that of the cell body itself and may represent a mechanism for sampling the local environment of each cell and for identifying target axons. Transitional cells have initiated one or more myelin sheaths; these cells progressively reduce the number of their radial processes as they increase the number of their myelin internodes. The radial processes of each transitional cell are most reduced in parts of the process arbor where ensheathment has begun, suggesting directional control in the elaboration or stability of the radial processes, Mature myelin-bearing oligodendrocytes entirely lack the radial processes and instead emit a few sparsely branching processes which connect cell bodies with myelin internodes. Three-dimensional analysis of the earliest stages in myelin sheath formation reveals two distinct phases, The initiating event in the formation of myelin internodes is the growth of thin unbranched processes, termed 'initiator processes', along axons. The second phase, spiral ensheathment of target axons, begins through the elaboration from each initiator process of lamellar extensions which extend circumferentially around the target axon and thereby form the first turn of its myelin sheath.