SPECIFICITY OF SYNAPSE FORMATION

细胞和分子生物学的最新进展表明， 细胞表面粘附和细胞外基质（ECM）分子是 对神经元的生长和引导很重要。这些实际作用 然而，最终必须使用体内研究来确定分子。 拟议的研究将检查这些分子在体内的作用， 利用小鸡的交感神经节前投射。这种神经 系统是理想的，因为这种研究的解剖是相对 简单，发展是很好的理解和假定的途径 轴突生长的速度是可预测的，并且可以被扰动。 建议的体内研究包括：（1）测定空间比， 细胞表面粘附和ECM分子的时间表达， 在体外促进神经元生长。（2）函数的使用 阻断剂，以检查这些分子对轴突生长的作用， 指导细胞表面粘附和ECM分子将通过 免疫和组织化学染色;将评价其功能 根据神经节前投射模式的变化， 局部注射功能性阻滞剂， 轴突这些分子对神经元特异性、生长和 肌束震颤将在不太复杂和更复杂的情况下进一步研究。 控制条件下，通过研究功能阻滞剂对 在组织外植体或低温恒温器切片上生长的神经元， 体外最后，作为确定新指导的第一步， 交感神经节前生长的分子， 组织外植体或低温切片上的节前投射 将检查从不同发育阶段的胚胎中获得的 来提供分子信号在何时何地被表达的信息。 这些对小鸡交感神经系统的系统研究 应该提供重要的见解轴突的指导机制， 从复杂的中央系统中获取知识是极其困难的。 神经系统

Recent advances in cell and molecular biology suggest that a number of cell surface adhesion and extracellular matrix (ECM) molecules are important for neuronal growth and guidance. The actual role of these molecules, however, must ultimately be determined using in vivo studies. The proposed research will examine the role of these molecules in vivo, using the sympathetic preganglionic projections of the chick. this neural system is ideal for such studies because the anatomy is relatively simple, the development is well understood and the presumptive pathways of growing axons are predictable and accessible for perturbation. Proposed in vivo studies include: (1) the determination of the spatio- temporal expression of cell surface adhesion and ECM molecules that are known to promote neuronal growth in vitro. and (2) the use of functional blockers to examine the role of these molecules on axonal growth and guidance. Cell surface adhesion and ECM molecules will be revealed by immuno- and histochemical staining; their functions will be evaluated according to changes in patterns of preganglionic projections subsequent to local injection of functional blockers to the pathway of preganglionic axons. The role of these molecules on neuronal specificity, growth, and fasciculation will be examined further under less complex and more controlled conditions, by studying the effects of functional blockers on identified neurons grown on tissue explants or cryostat sections in vitro. Finally, as a first step towards identifying novel guidance molecules in sympathetic preganglionic outgrowth, the specificity of preganglionic projections on tissue explants or cryostat sections obtained from embryos of different developmental stages will be examined to provide information of where and when molecular cues are expressed. These systematic studies on the sympathetic nervous system of the chick should provide important insights on axonal guidance mechanisms, knowledge that is extremely difficult to obtain from the complex central nervous system.