Hirano S, Kumaresan K, Ali M M, Sohal G S
Department of Anatomy, Medical College of Georgia, Augusta 30912.
Int J Dev Neurosci. 1991;9(4):371-9. doi: 10.1016/0736-5748(91)90059-u.
About half of the trochlear motor neurons die during the course of normal development. The present study was undertaken to determine whether the afferent synapses form before the onset of motor neuron death and also to determine whether the number of synapses differs between the healthy and degenerating trochlear motor neurons. Brains of duck embryos from days 10 to 20 were prepared for quantitative electron microscopical observations on synaptogenesis. Results indicate that synapses form on the trochlear motor neuron soma before cell death begins suggesting that afferent input is in a position to exert an influence on survival or death of motor neurons. There were no significant differences in the number of synapses between the healthy and dying neurons during the period of cell death. This observation suggests that the mechanism by which afferent synapses could be involved in neuron survival or death is not related to the number of synapses on the cell soma. The number of synapses on the cell process, synaptic transmission and/or molecules released at the synapses are likely candidates for the mechanism of action of afferent input.
在正常发育过程中，约一半的滑车运动神经元会死亡。本研究旨在确定传入突触是否在运动神经元死亡开始之前形成，以及健康和退化的滑车运动神经元之间的突触数量是否存在差异。制备了第10至20天鸭胚的大脑，用于对突触发生进行定量电子显微镜观察。结果表明，在细胞死亡开始之前，突触就已在滑车运动神经元胞体上形成，这表明传入输入能够对运动神经元的存活或死亡产生影响。在细胞死亡期间，健康神经元和濒死神经元之间的突触数量没有显著差异。这一观察结果表明，传入突触参与神经元存活或死亡的机制与胞体上的突触数量无关。细胞突起上的突触数量、突触传递和/或突触处释放的分子可能是传入输入作用机制的候选因素。
