SPECIFICITY OF SYNAPSE FORMATION

这项建议是旨在了解 大鼠神经节前和节后神经元之间适当的突触联系 交感神经系统是在胚胎时期建立的。 发展。利用组织学和电生理学技术，我 将在雏鸟身上检查导致有序的发育事件 节前和节后神经元之间的突触关系。这些 实验将描绘交感神经节形成的时间。 从神经脊来看，节前和节后轴突的生长和 这些事件之间的时间关系。在第二组 研究，我将测试胚胎轴突的生长能力，以找到它们 在对环境进行试验性操作后，选择合适的目标。 这些研究将检验三个假设：1)投射模式 节前神经元在脊髓中的节段性起源 脊髓或脊髓外的组织环境？2)是 引导节前轴突所需的靶线索是 节前轴突对神经节细胞的分段选择性神经支配 根据节前和节后神经元的节段性起源 神经轴？拟议的实验将利用可访问性 可能的鸡胚：1)移植节前神经元 在不中断其目标细胞的情况下将其转移到新环境，2)移除 在此之前产生特定交感神经节的神经脊细胞 它们的迁移且不损害节前神经元，3)标记两者 节前和节后神经元起源于延髓的特定节段 神经轴，并检查标记细胞之间的突触相互作用 解剖学和细胞内记录方法的结合。 这些研究将为胚胎发育提供新的数据。 交感神经节中的特定突触连接。同时， 这些研究的结果可能代表了普遍的原则， 适用于中枢神经系统的发育。

This proposal is a continuation of studies aimed at understanding how appropriate synaptic connections between pre- and postganglionic neurons in the sympathetic nervous system are established during embryonic development. Using histological and electrophysiological techniques, I will examine, in the chick, the developmental events that result in ordered synaptic relations between pre- and postganglionic neurons. These experiments will delineate the time of formation of sympathetic ganglia from the neural crest, the outgrowth of pre- and postganglionic axons and the temporal relationships between these events. In a second group of studies, I will test the ability of growing embryonic axons to find their appropriate targets after experimental manipulations of the environment. These studies will test three hypotheses: 1) Are the projection patterns of preganglionic neurons determined by their segmental origin in the spinal cord or by the tissue environment outside of the spinal cord? 2) are target cues required for the guidance of preganglionic axons? 3) Is segmentally selective innervation of ganglion cells by preganglionic axons based on the segmental origins of pre- and postganglionic neurons in the neuraxis? The proposed experiments will exploit the accessibility of the chick embryo where it is possible to: 1) transplant preganglionic neurons to a novel environment without disrupting their target cells, 2) remove the neural crest cells that give rise to specific sympathetic ganglia prior to their migration and without damage to preganglionic neurons, 3) label both pre- and postganglionic neurons arising from particular segments of the neuraxis and examine the synaptic interactions between labelled cells using a combination of anatomical and intracellular recording methods. These studies will provide new data on the embryonic development of specific synaptic connection in sympathetic ganglia. At the same time, results from these studies are likely to represent general principles that are applicable to the development of the central nervous system.