SPECIFICITY OF SYNAPSE FORMATION

细胞和分子生物学的最新进展表明，许多 细胞表面黏附和细胞外基质(ECM)分子 对神经元的生长和引导很重要。它们的实际作用 然而，分子最终必须通过活体研究来确定。 这项拟议的研究将检验这些分子在体内的作用， 利用小鸡的交感神经节前投射。这个神经 系统是此类研究的理想系统，因为解剖学相对 简单地说，发展是很好理解的，假定的路径是 生长中的轴突的数量是可预测的，并且容易受到扰动。 建议的活体研究包括：(1)空间分布的测定 细胞表面黏附和细胞外基质分子的时间表达 已知能在体外促进神经元生长。以及(2)功能语法的使用 阻滞剂研究这些分子对轴突生长和 指导。细胞表面黏附和细胞外基质分子将通过以下方式揭示 免疫和组织化学染色；将评估它们的功能 根据节前投射模式的变化 节前通路局部注射功能性阻滞剂 轴突。这些分子在神经元特异性、生长和发育中的作用 我们将在不太复杂和更复杂的情况下进一步研究这种情况 受控条件，通过研究功能阻滞剂对 在组织外植体或冷冻切片上生长的已鉴定神经元 体外培养。最后，作为确定小说指导的第一步 交感神经节前突起中的分子，特异性 组织外植体或冷冻机切片上的节前投射 将检测从不同发育阶段的胚胎中获得的 以提供何时何地表达分子线索的信息。 雏鸡交感神经系统的系统研究 应该为轴突引导机制提供重要的见解， 从复杂的中心获得极其困难的知识 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.