Berthold C H, Rydmark M
J Neurocytol. 1983 Jun;12(3):475-505. doi: 10.1007/BF01159386.
The general ultrastructural organization of nodes of Ranvier in peripheral nerve fibres from 2 to 20 microns 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 fibre size up to a fibre diameter of 8-10 microns. At this fibre size the nodal gap was of a fairly even height (1 micron) 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 fibres (D less than 3 microns) the nodal gap was low (less than 0.1 microns) and contained no or few microvilli. In fibres greater than 10 microns in diameter the relative size and the degree of structural order of the nodal Schwann cell compartment decreased with increasing fibre size. Drastic sectorial variations in nodal gap height and local thinning-out of the brush-border became prominent features in the largest fibres. 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 extracellular 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.
利用成年猫的腹侧和背侧脊髓神经根连续切片，研究了直径为2至20微米（D）的外周神经纤维中朗飞结的一般超微结构组织。进行这项研究是为了收集和整理对朗飞结进行形态计量分析所需的必要信息。在所有情况下，朗飞结可分为中央结轴突段和周围的结雪旺细胞区室。后者包括结间隙基质物质、或多或少重叠的结雪旺细胞环，通常还有从结雪旺细胞环发出并占据结间隙的雪旺细胞刷状缘。结雪旺细胞区室的相对大小和组织水平随着纤维大小的增加而增加，直至纤维直径达到8 - 10微米。在这个纤维大小下，结间隙在结轴突周围各处具有相当均匀的高度（1微米），并包含由紧密排列、或多或少呈放射状排列的雪旺细胞微绒毛组成的厚刷状缘。在非常小的纤维（D小于3微米）中，结间隙很低（小于0.1微米），且没有或只有很少的微绒毛。在直径大于10微米的纤维中，结雪旺细胞区室的相对大小和结构有序程度随着纤维大小的增加而降低。结间隙高度的剧烈扇形变化和刷状缘的局部变薄在最大的纤维中成为突出特征。讨论了结雪旺细胞区室在体内可能的组织形式。初步计算表明，直接围绕结轴突的细胞外空间可能相当小，并且这个细胞外空间与神经内膜空间之间开放进行自由交流的区域可能非常有限，仅占结轴膜面积的2%。还讨论了计算各种结结构参数的算法。
