Hollingworth T, Berry M
Philos Trans R Soc Lond B Biol Sci. 1975 May 8;270(906):227-64. doi: 10.1098/rstb.1975.0008.
The connectivity within the dendritic array of Purkinje cells in the cerebellum and pyramidal cells of the neocortex of the rat, stained by the Golgi-Cox method, has been quantified by the method of network analysis. Connectivity was characterized either by applying the system of Strahler ordering, which assigns a relative order of magnitude to each branch of the arborescence or by the identification of unique topological branching patterns within the tree. The former method has been used to define the entire dendritic array of the Purkinje cell and the apical system of neocortical pyramids. It has been shown that the relation between the numbers of branches of successive Strahler order in Purkinje cells form an inverse geometric series in which the highest order is unity and the ratio between successive orders approximates to 3. On the other hand, the apical dendrites of neocortical pyramids exhibit two bifurcation ratios, i.e. a ratio of 3 between low orders and a ratio of 4 between higher orders. A computer simulation technique was used to generate networks of a size comparable with the Purkinje cell networks and grown according to two hypotheses namely, a 'terminal growth model' in which additional segments were added randomly to the terminal branches only and a 'segmental growth model' in which additional segments were added randomly to any branch within the array including terminal branches. Subsequent ordering of the simulated trees revealed that the relation between the numbers of successive orders for networks generated according to the 'segmental model' tended towards an inverse geometric series with a ratio of 4 and that generated according to the 'terminal model' tended towards a ratio of 3. This result showed that the dendritic tree of Purkinje cells grow in a manner indistinguishable from a system adding branches to random terminal segments and that neocortical apical dendrites add their collateral branches to random segments of the apical shaft but that the collateral branches themselves grow by random terminal branching. The possibility that such conclusions may be influenced by loss of branches incurred by either a failure of impregnation, by sectioning, or by environmental influences was investigated by means of a computer technique...
采用高尔基-考克斯（Golgi-Cox）染色法对大鼠小脑浦肯野细胞（Purkinje cell）和新皮质锥体细胞的树突阵列内的连接性进行了网络分析定量。连接性的特征可通过应用斯特拉勒（Strahler）排序系统来表征，该系统为树状分支的每个分支赋予一个相对数量级，或者通过识别树内独特的拓扑分支模式来表征。前一种方法已被用于定义浦肯野细胞的整个树突阵列和新皮质锥体的顶端系统。结果表明，浦肯野细胞中连续斯特拉勒阶的分支数量之间的关系形成一个反几何级数，其中最高阶为1，连续阶之间的比率约为3。另一方面，新皮质锥体的顶端树突表现出两个分支比率，即低阶之间的比率为3，高阶之间的比率为4。使用计算机模拟技术生成了与浦肯野细胞网络大小相当的网络，并根据两个假设进行生长，即“末端生长模型”，其中仅向末端分支随机添加额外节段，以及“节段生长模型”，其中向阵列内的任何分支（包括末端分支）随机添加额外节段。对模拟树的后续排序显示，根据“节段模型”生成的网络的连续阶数量之间的关系趋向于比率为4的反几何级数，而根据“末端模型”生成的网络趋向于比率为3的反几何级数。这一结果表明，浦肯野细胞的树突树以一种与向随机末端节段添加分支的系统无法区分的方式生长，新皮质顶端树突将其侧支添加到顶端轴的随机节段，但侧支本身通过随机末端分支生长。通过计算机技术研究了这些结论可能受到因浸染失败、切片或环境影响而导致的分支丢失影响的可能性……
