Larkman A U
University Laboratory of Physiology, Oxford University, United Kingdom.
J Comp Neurol. 1991 Apr 8;306(2):307-19. doi: 10.1002/cne.903060207.
The aim of this study was to provide quantitative descriptions of the branching patterns of basal and apical dendrites of pyramidal neurones from the visual cortex of the rat. Thirty-nine neurones from cortical layers 2/3 and 5, that had been injected with horseradish peroxidase, reconstructed, and measured with the light microscope as part of an earlier study (Larkman and Mason, '90; J. Neurosci. 10:1407-1414), were used. The cells had previously been divided into three classes, layer 2/3 cells and thick and slender layer 5 cells, on the basis of their dendritic morphology. The branching pattern of the basal and apical oblique dendrites was similar for all the cells. Between 3 and 9 basal trees arose from the soma and the number of tips in each tree varied widely, between 1 and 13. The path lengths of all the basal dendrites of a given cell were relatively constant, however. Most basal dendritic branching occurred close to the soma, such that terminal segments were much longer than intermediate segments and contributed approximately 90% of the total dendritic length of each tree. Terminal segments showed only a narrow range of diameters. Most apical oblique trees arose from the proximal part of the apical trunk. They tended to be less highly branched but were otherwise extremely similar to basal trees. Distal oblique trees were unbranched or branched only once, and their terminal segments tended to be shorter and thinner than those of basal trees. The branching pattern of the apical terminal arbors was different, with many longer intermediate segments. The terminal segments tended to be thinner than those of basal or proximal oblique trees. Slender layer 5 cells were without obvious terminal arbors. The basal and proximal oblique dendrites jointly sampled a roughly spherical volume of cortex centred about the soma, and together they accounted for the substantial majority of the cell's total dendritic shaft membrane area. Comparisons with previous studies suggest that intracellular HRP injection can yield a more complete visualization of dendritic morphology than is obtained using Golgi-based methods (unless cells are reconstructed across tissue slabs), and can therefore result in a different view of the relative importance of the various components that make up the cell's dendritic system.
本研究的目的是对大鼠视觉皮层锥体细胞的基底树突和顶树突的分支模式进行定量描述。作为早期研究（Larkman和Mason，1990年；《神经科学杂志》10：1407 - 1414）的一部分，使用了39个来自皮层2/3层和5层、已注射辣根过氧化物酶、进行了重建并在光学显微镜下测量的神经元。这些细胞先前根据其树突形态被分为三类，即2/3层细胞以及厚层和细长层5细胞。所有细胞的基底树突和顶斜树突的分支模式相似。3至9个基底树突丛从胞体发出，每个树突丛的末梢数量差异很大，在1至13个之间。然而，给定细胞的所有基底树突的路径长度相对恒定。大多数基底树突分支发生在靠近胞体的位置，使得末端节段比中间节段长得多，并且占每个树突丛总树突长度的约90%。末端节段的直径范围很窄。大多数顶斜树突丛从顶干的近端部分发出。它们的分支程度往往较低，但在其他方面与基底树突丛极为相似。远斜树突不分支或仅分支一次，其末端节段往往比基底树突的末端节段更短更细。顶末端分支的分支模式不同，有许多更长的中间节段。末端节段往往比基底或近端斜树突的末端节段更细。细长层5细胞没有明显的末端分支。基底树突和近端斜树突共同采样了一个以胞体为中心的大致球形的皮层体积，它们一起占了细胞总树突轴膜面积的绝大部分。与先前研究的比较表明，与基于高尔基方法（除非跨组织切片重建细胞）相比，细胞内辣根过氧化物酶注射能够更完整地呈现树突形态，因此可能会对构成细胞树突系统的各种成分的相对重要性产生不同的看法。
