AXON-TARGET INTERACTIONS IN DEVELOPING CEREBELLUM

这项拟议的研究将调查正在生长的轴突的成熟情况， 使用小鼠小脑作为模型系统，并将解决三个相关的 问题：1)过渡期间形态和细胞学的变化 生长锥至成熟的突触茎；2)生长的顶端和 成熟的突触周围反映轴突的起源与 生长顶端与其微环境的相互作用；(3)对什么 生长轴突在突触形成中采取的策略 连接包括错误，如果是这样，它们进行了哪些重新安排以形成 适当的联系。一旦形成具体的步骤 连接被描绘，这种特异性的分子基础可以在 未来是可以探索的。 未成熟轴突的形式和生长的尖端将在 向靶结构生长，在轴突等待和 在形成突触连接的过程中。轴突将被标记为 辣根过氧化物酶(HRP)脑片注射，然后 光镜和电子显微镜分析。的三维形态 轴突及其生长的尖端将与它们的细胞学相关， 突触模式和与周围细胞的相互作用。不断增长的 生长期间有关轴突的提示将与时期的提示进行对比。 等待和突触发生的过程。等待轴突与靶的关系 细胞将用HRP标记和特异性抗血清来确定 突触和浦肯野细胞。攀援纤维和苔藓纤维将被识别 通过注射其特定的轴突路径或起源核，以及 关于临时连接重排的参数 具有攀缘纤维和苔藓纤维的轴突的攀缘纤维分支 功能将被记录在案。删除源文件的影响 攀爬纤维对苔藓纤维的成熟度将进行评估。这个 轴突生长尖端与靶细胞的相互作用将通过 纯化颗粒或浦肯野细胞与小脑传入神经共培养。

The proposed research would investigate the maturation of growing axons, using mouse cerebellum as a model system, and would address three related issues: 1) the changes in form and cytology during the transition of growth cone to mature synaptic arbor; 2) to what extent the growing tip and mature synaptic bouton reflect the origin of the axon versus the interaction of the growing tip with its microenvironment; (3) to what extent the strategies taken by growing axons in formation of synaptic connection include error, and if so, what rearrangements they make to form proper connections. Once the steps in the formation of specific connections are delineated, the molecular basis for such specificity can in the future be explored. The form of immature axons and growing tips will be characterized during outgrowth towards target structures, during the period axons wait and during the formation of synaptic connections. Axons will be labeled with horseradish peroxidase (HRP) by injection into brain slices, followed by light and electron microscopic analysis. The three dimensional forms of axons and their growing tips will be correlated with their cytology, synaptic patterns and interactions with surrounding cells. The growing tips on axons during outgrowth will be contrasted with those during periods of waiting and synaptogenesis. The relations of waiting axons with target cells will be determined with HRP labeling and specific antisera to synapses and Purkinje cells. Climbing and mossy fibers will be identified by injection of their specific axon pathways or nucleus of origin, and the parameters of the rearrangement of transient connections of supernumerary climbing fiber branches and of axons with both climbing and mossy fiber features will be documented. The effect of deletion of the source of climbing fibers on the maturation of mossy fibers will be assessed. The interaction of axonal growing tips with target cells will be studied by co-culturing cerebellar afferents with purified granule or Purkinje cells.