Tseng G F, Hu M E
Department of Anatomy, College of Medicine, National Taiwan University, Taipei, ROC.
Acta Anat (Basel). 1996;155(3):184-93. doi: 10.1159/000147803.
The effect of distal axonal injury on the soma-dendritic morphology of intrinsic central neurons was examined using adult rat lumbar spinal cord-projecting rubrospinal neurons as a model. The soma-dendritic morphology was revealed using an improved Golgi-aldehyde method. Impregnated neurons were reconstructed in the two-dimensional plane for analysis. Four weeks after axotomy, neurons had reduced soma sizes and remained multipolar in shape. Some dendrites were found to end not far from their cell bodies. In addition, no long dendrite was identified following axotomy. Sholl's analysis [The Organization of the Cerebral Cortex. London, Methuen, [1956] revealed that axotomized neurons had fewer dendritic branches than control neurons. Total dendritic length was also reduced. Subsequent analyses showed that the average number of dendritic trunks was not altered however the mean number of terminal branches per dendritic trunk was reduced. The dendritic membrane of the normal neurons was usually smooth with occasional short protuberances on the proximal dendrites and spines on the distal dendrites, which did not change after axotomy. In control neurons, we identified an elaborate type of dendritic structure named dendritic appendage aggregates. These aggregates were located preferentially on terminal dendrites and were classified into three categories according to their complexity. The incidence of occurrence for these aggregates decreased following distal axotomy. These phenomena indicate that rat lumbar spinal cord-projecting rubrospinal neurons retract their distal dendrites in response to distal axotomy. The observed anatomic restructuring following axonal injury is likely to be accompanied by an alteration of afferents which normally synapse on distal dendrites.
以成年大鼠腰脊髓投射红核脊髓神经元为模型，研究了轴突远端损伤对中枢内在神经元胞体-树突形态的影响。采用改良的高尔基醛法显示胞体-树突形态。对浸渍的神经元在二维平面上进行重建以进行分析。轴突切断后四周，神经元胞体大小减小，仍呈多极形状。发现一些树突在离其细胞体不远的地方终止。此外，轴突切断后未发现长树突。肖尔分析[《大脑皮层的组织》。伦敦，梅休因，[1956年]]显示，轴突切断的神经元比对照神经元的树突分支更少。总树突长度也缩短了。随后的分析表明，树突干的平均数量没有改变，然而每个树突干的终末分支的平均数量减少了。正常神经元的树突膜通常是光滑的，近端树突上偶尔有短突起，远端树突上有棘，轴突切断后这些都没有改变。在对照神经元中，我们发现了一种精细的树突结构类型，称为树突附属物聚集体。这些聚集体优先位于终末树突上，并根据其复杂性分为三类。远端轴突切断后，这些聚集体的发生率降低。这些现象表明，大鼠腰脊髓投射红核脊髓神经元对远端轴突切断的反应是缩回其远端树突。轴突损伤后观察到的解剖结构重组可能伴随着通常与远端树突形成突触的传入神经的改变。
