ELECTRON-MICROSCOPIC SERIAL SECTION ANALYSIS OF NODES OF RANVIER IN LUMBOSACRAL SPINAL ROOTS OF THE CAT - ULTRASTRUCTURAL ORGANIZATION OF NODAL COMPARTMENTS IN FIBERS OF DIFFERENT SIZES
ELECTRON-MICROSCOPIC SERIAL SECTION ANALYSIS OF NODES OF RANVIER IN LUMBOSACRAL SPINAL ROOTS OF THE CAT - ULTRASTRUCTURAL ORGANIZATION OF NODAL COMPARTMENTS IN FIBERS OF DIFFERENT SIZES
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DOI：
10.1007/bf01159386
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发表时间：
1983-01-01
期刊：
影响因子：
--
通讯作者：
RYDMARK, M
中科院分区：
文献类型：
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作者：
BERTHOLD, CH;RYDMARK, M
用连续切片的脊神经腹根和背根，观察了成年猫外周神经纤维中直径为2-20微米的Ranvier结节的一般超微结构。进行这项研究是为了收集对兰维尔结节进行形态计量分析所需的信息，并将其系统化。在所有病例中，Ranvier结节均可分为中央结节轴索段和周围结节雪旺细胞室。后者包括一种结节间隙基质物质，或多或少重叠的结节雪旺细胞环，以及通常从结节雪旺细胞环发出的占据结节间隙的雪旺细胞刷状边界。节状雪旺细胞室的相对大小和组织水平随着纤维直径的增加而增加，直至纤维直径为8-10µm。在这种纤维大小下，结节间隙在结节轴突周围是相当均匀的高度(1微米)，并包含一层浓密排列的、或多或少呈放射状排列的雪旺细胞微绒毛的浓密的刷状边缘。在极小的纤维(D<；3µm)中，节隙很低(<；0.1µm)，没有或很少微绒毛。在直径为10微米的纤维中，节状雪旺细胞室的相对大小和结构有序度随着纤维尺寸的增加而减小。在最大的纤维中，结节间隙高度的显著扇形变化和刷状边缘的局部变薄成为显著特征。文中还讨论了结节雪旺细胞室可能的体内组织。初步计算表明，直接围绕结节轴突的细胞外间隙可能很小，这种细胞外间隙和神经内间隙之间的自由通信开放的面积可能非常有限，仅占结节轴膜面积的2%。讨论了各种节点结构参数的计算方法。
The general ultrastructural organization of nodes of Ranvier in peripheral nerve fibers from 2-20 .mu.m in diameter (D) was investigated in the adult cat using serially sectioned ventral and dorsal spinal roots. The study was performed in order to collect and systematize information considered necessary for a morphometric analysis of the node of Ranvier. In all cases a node of Ranvier could be divided into a central nodal axon segment and a surrounding nodal Schwann cell compartment. The latter included a nodal gap matrix substance, more or less overlapping nodal Schwann cell collars and, as a rule, also a Schwann cell brush-border emanating from the nodal Schwann cell collars and occupying the nodal gap. The relative size and the organization level of the nodal Schwann cell compartment increased with increasing fiber size up to a fiber diameter of 8-10 .mu.m. At this fiber size the nodal gap was a fairly even height (1 .mu.m) all around the nodal axon and contained a thick brush-border of densely packed, more or less radially arranged Schwann cell microvilli. In very small fibers (D < 3 .mu.m) the nodal gap was low (< 0.1 .mu.m) and contained no or few microvilli. In fibers > 10 .mu.m in diameter the relative size and the degree of structural order of the nodal Schwann cell compartment decreased with increasing fiber size. Drastic sectorial variations in nodal gap height and local thinning-out of the brush-border became prominent features in the largest fibers. The possible in vivo organization of the nodal Schwann cell compartment is discussed. Preliminary calculations indicate that the extracellular space directly surrounding the nodal axon might be quite small and that the area open for free communication between this extracelluar space and the endoneurial space might be very much restricted, measuring as little as 2% of the area of the nodal axolemma. Algorithms for calculating various nodal structural parameters are discussed.