Nordlander R H
J Comp Neurol. 1986 Nov 15;253(3):403-13. doi: 10.1002/cne.902530308.
The purpose of this study was to identify, characterize, and follow the morphogenesis of motoneurons innervating tail myotomes of Xenopus during early and middle larval stages (33-48). Application of horseradish peroxidase to a single myotome results in a column of labeled motor cells extending over four spinal segments. By midlarval stages two morphologically distinct cell types were recognizable in this column-primary and secondary motoneurons. Primary motoneurons occupied the more rostral and secondary motoneurons the more caudal portions of the column with some overlap of the two populations. Primary neurons developed earlier, were larger, and displayed thicker axons and proximal dendrites. Secondary neurons, in contrast, were smaller, more variable in configuration and dendritic distribution, and displayed thinner axons and dendrites. Development of the labeled motor column during the period observed involved the addition of more labeled neurons, principally secondary cells, and the enlargement of individual cell somata with the progressive elaboration of more and longer dendrites into the developing lateral fasciculus.
本研究的目的是识别、描述并追踪非洲爪蟾幼体早期和中期（33 - 48期）支配尾部肌节的运动神经元的形态发生。将辣根过氧化物酶应用于单个肌节，会导致一列标记的运动细胞延伸跨越四个脊髓节段。到幼体中期，在这一列中可识别出两种形态上不同的细胞类型——初级和次级运动神经元。初级运动神经元占据该列更靠前的部分，次级运动神经元占据更靠后的部分，这两个群体有一些重叠。初级神经元发育较早，体积较大，轴突和近端树突较粗。相比之下，次级神经元较小，形态和树突分布更具变异性，轴突和树突较细。在观察期内，标记运动柱的发育涉及更多标记神经元（主要是次级细胞）的增加，以及单个细胞体的增大，同时更多更长的树突逐渐伸入发育中的外侧束。
