Clark R D
J Comp Neurol. 1976 Nov 15;170(2):253-65. doi: 10.1002/cne.901700209.
The morphological effects of separation from the soma were examined in isolated arborization and isolated axon segments of an identified motor neuron in the Polynesian field cricket, Teleogryllus oceanicus. The identified neuron, the contralateral dorsal longitudinal motor neuron of the metathoracic ganglion (CDLM), possesses an arborization most of which lies contralateral to its soma within the metathoracic ganglion. Midline surgical lesions in the metathoracic ganglion separated CDLM into a distal segment composed of the axon and most of the arborization, and a proximal segment comprised of the remaining arborization, neuritie, and soma. Isolated axonal segments were produced by cutting the nerve root containing the axon of CDLM close to the ganglion. The normal anatomy of CDLM was determined by axonal dye-fills using cobaltous chloride. Morphological changes in the isolated arborization of CDLM were examined by axonal dye-fills at successive time intervals. Changes in the isolated CDLM axon were examined via dissection and histological cross-sections of the distal nerve at graded time intervals. In one example, a remnant of the isolated CDLM arborization survived to 168 days postoperative, a time comparable to the longest previously-reported physiological and morphological survival times of distal axonal segments of invertebrates. In general the isolated arborization does not survive this long. Normally-occurring branches of the arborization can be preserved about 0 to 50 days. After this period branches of the arborization seem to be lost in progressive fashion from smaller to larger, leading to complete loss of the arborization and axon in most cases at 100 or more postoperative days. There is evidence for the presence of supernumerary fibers in the isoalted CDLM arborization between 0 to 63 days postoperative. Such supernumerary fibers indicate an independent capacity for outgrowth of the isolated arborization without connection to the nucleus. The distal axonal segment of CDLM degenerates physiologically and morphologically within 4 to 15 days after peripheral nerve section. This time course is close to that of Wallerian degeneration of vertebrate peripheral nerve axons.
在波利尼西亚田蟋Teleogryllus oceanicus中，对一个已鉴定运动神经元的孤立树突分支和孤立轴突节段进行了与胞体分离后的形态学效应研究。这个已鉴定的神经元，即后胸神经节的对侧背纵运动神经元（CDLM），其树突分支大部分位于后胸神经节内与其胞体相对的一侧。在后胸神经节进行中线手术损伤，将CDLM分为一个由轴突和大部分树突分支组成的远端节段，以及一个由其余树突分支、神经突和胞体组成的近端节段。通过在靠近神经节处切断包含CDLM轴突的神经根来制备孤立的轴突节段。使用氯化钴进行轴突染料填充来确定CDLM的正常解剖结构。在连续的时间间隔进行轴突染料填充，以检查CDLM孤立树突分支的形态变化。通过在分级时间间隔对远端神经进行解剖和组织学横切，来检查孤立的CDLM轴突的变化。在一个例子中，孤立的CDLM树突分支的一个残余部分存活到术后168天，这个时间与之前报道的无脊椎动物远端轴突节段最长的生理和形态学存活时间相当。一般来说，孤立的树突分支存活不了这么久。树突分支正常出现的分支可以保留大约0到50天。在此之后，树突分支的分支似乎以渐进的方式从较小的分支逐渐丢失到较大的分支，在大多数情况下，术后100天或更长时间会导致树突分支和轴突完全丧失。有证据表明，在术后0到63天之间，孤立的CDLM树突分支中存在多余的纤维。这种多余的纤维表明孤立的树突分支具有在不与细胞核连接的情况下独立生长的能力。CDLM的远端轴突节段在周围神经切断后4到15天内发生生理和形态学退化。这个时间进程与脊椎动物周围神经轴突的华勒氏变性相近。
