Faulkes Z, Paul D H
Department of Biology, University of Victoria, B.C., Canada.
Brain Behav Evol. 1997;49(3):162-78. doi: 10.1159/000112990.
We describe the numbers, central positions, and axonal exit routes of the distal leg motor neurons of four decapod species: squat lobsters (Munida quadrispina), spiny sand crabs (Blepharipoda occidentalis), mole sand crabs (Emerita analoga), and signal crayfish (Pacifastacus leniusculus). As predicted by previous physiological and anatomical identification of axons at the periphery in crayfish and lobsters, cobalt backfills reveal about seventeen cell bodies, which are found in four areas in the ganglion. By comparing their positions and neurite morphologies with the previously identified neurons, functional identifications could be assigned to most of them. The common inhibitor and stretcher inhibitor are located posterior-medial. An anterior-lateral cluster of about twelve somata includes the opener identical to stretcher excitor, one of two bender excitors (bender excitor alpha), four flexor excitors, and two excitors each to the extensor, reductor, and closer muscles. Three cell bodies are posterior-lateral. Of these, the opener inhibitor and the second bender excitor (bender excitor beta) are on about the same dorsoventral plane. The third posterior-lateral cell, the accessory flexor excitor, is noticeably more dorsal than the other two posterior-lateral cell bodies. The reductor muscle is innervated by at least three neurons: the putative common inhibitor and fast and slow excitors. None of the leg motor neurons project into the contralateral hemiganglion. The most variable feature across species is the nerve through which motor axons exit the ganglion: axons leave the ganglia via different routes in each of the four species examined. These differences in the axons' pathway, however, are insufficient to explain the differences in motor output and behaviour of these four species.
我们描述了四种十足目动物腿部远端运动神经元的数量、中心位置和轴突穿出路径：蹲龙虾（四棘刺龙虾）、多刺沙蟹（西方鳃足蟹）、鼹鼠沙蟹（加州美人虾）和信号小龙虾（美洲螯虾）。正如之前对小龙虾和龙虾外周轴突进行生理和解剖鉴定所预测的那样，钴离子逆行填充显示约有17个细胞体，分布在神经节的四个区域。通过将它们的位置和神经突形态与先前鉴定的神经元进行比较，可以对其中大多数进行功能鉴定。常见抑制剂和伸展抑制剂位于后内侧。大约十二个躯体的前外侧簇包括与伸展兴奋器相同的 opener、两个弯曲兴奋器之一（弯曲兴奋器α）、四个屈肌兴奋器，以及分别支配伸肌、内收肌和闭合肌的两个兴奋器。三个细胞体位于后外侧。其中，opener抑制剂和第二个弯曲兴奋器（弯曲兴奋器β）位于大致相同的背腹平面。第三个后外侧细胞，即副屈肌兴奋器，明显比其他两个后外侧细胞体更靠背侧。内收肌至少由三个神经元支配：假定的常见抑制剂以及快速和慢速兴奋器。没有腿部运动神经元投射到对侧半神经节。不同物种之间最可变的特征是运动轴突穿出神经节的神经：在所研究的四个物种中，轴突通过不同的路径离开神经节。然而，轴突路径的这些差异不足以解释这四个物种在运动输出和行为上的差异。
