SPECIFICITY OF SYNAPSE FORMATION

这项建议是旨在了解如何 神经节前和节后神经元之间的适当突触连接， 交感神经系统是在胚胎期建立 发展 使用组织学和电生理技术， 将检查，在小鸡，导致有序的发展事件， 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， 从神经嵴，前和节后轴突的生长， 这些事件之间的时间关系。 的第二组中的 研究中，我将测试胚胎轴突生长的能力，以找到它们的 在环境的实验操作之后的适当的目标。 这些研究将检验三个假设：1）投射模式 节前神经元的节段性起源决定于脊髓 脊髓还是脊髓外的组织环境？ 2)是 引导节前轴突所需的目标线索？ 3)是 节前轴突对节细胞的节段性选择性神经支配 根据节前和节后神经元的节段起源， neuraxis？ 拟议的实验将利用 鸡胚，其中可以：1）移植节前神经元 新的环境，而不破坏他们的靶细胞，2）去除 神经嵴细胞，产生特定的交感神经节之前， 它们的迁移和不损害节前神经元，3）标记两者 神经节前和节后神经元来自特定的节段， 神经轴和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。 这些研究将提供关于胚胎发育的新数据。 交感神经节中特殊的突触连接。 与此同时， 这些研究的结果可能代表了一般原则， 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.