SEGMENTAL DIFFERENTIATION IN THE NERVOUS SYSTEM

这项工作的长期目标是了解某些 发展的基本机制，特别是在 神经发生、分化和选择性突触形成。这个目标 是通过研究中枢神经系统的各个区域如何 系统和这些区域内的神经细胞，在形态上和 在发育过程中彼此在生理上存在差异 以执行专门的职能。神经节段的神经系统 药用水蛭之所以被选为这些实验的对象，是因为它的 简单性，研究单个识别的神经元的可能性 重复，以及胚胎和胚胎后的现成可获得性 实验操作的各个阶段。 这个项目包括两个部分。第一部分是关于 中枢神经元的产生可能是怎样的一个非常基本的问题 由外周器官调节的。它包括对相互作用的研究 在男性生殖器和支配它的两个中央神经节之间。 这种相互作用是由一个感应信号介导的，该感应信号触发了 这些神经元中一类特殊神经元的诞生和分化 神经节。提出的实验旨在得出以下问题的答案 问题(1)互动具体发生在什么时候？，(2) 由神经系统或目标定义的交互时间 组织？，以及(3)哪些细胞是感应信号的来源， 哪些细胞将其携带到中枢神经系统，哪些细胞对 信号？与此相关的细胞成分的鉴定 互动是未来探索的必要前提 这种相互作用的分子机制。 该项目的第二部分解决了另一个基本问题： 突触连接形成的选择性是如何实现的。它 包含对以下内容之间的交互的全面检查 已鉴定的运动神经元和外周组织导致 与神经元的目标--男性--形成神经肌肉连接 生殖器。这些实验是以互补的方式进行的， 无论是在动物体内还是在培养中的分离细胞中。 一种多方面的方法，涉及胚胎微扰和 电生理、解剖学和免疫细胞学技术，将 受雇于这个项目。进一步详细研究这些基本原理 药用水蛭的简单神经系统中的问题将提供 适用于正常和异常研究的有价值的见解 开发更复杂的系统。

The long-range goal of this work is to understand certain fundamental mechanisms of development, particularly regarding neurogenesis, differentiation and selective synapse formation. This goal is addressed by studying how individual regions of the central nervous system, and nerve cells within those regions, become morphologically and physiologically differentiated from one another during development in order to perform specialized functions. The segmented nervous system of the medicinal leech was chosen for these experiments because of its great simplicity, the possibility of studying individual identified neurons repeatedly, and the ready accessibility of embryonic and postembryonic stages to experimental manipulation. There are two parts to this project. The first part concerns the very basic question of how the generation of central neurons may be regulated by peripheral organs. It comprises the study of an interaction between the male genitalia and the two central ganglia that innervate it. This interaction is mediated by an inductive signal that triggers the birth and differentiation of a special population of neurons in these ganglia. The experiments proposed are designed to yield answers to the questions (1) when exactly does the interaction take place?, (2) is the time of interaction defined by the nervous system or by the target tissue?, and (3) which cells are the source of the inductive signal, which carry it to the central nervous system, and which cells respond to the signal? Identification of the cellular elements involved in this interaction is a necessary prerequisite for the future exploration of the molecular mechanisms of this interaction. The second part of this project addresses another basic question: how selectivity in the formation of synaptic connections is achieved. It consists of a comprehensive examination of the interactions between an identified motor neuron and peripheral tissues that result in the formation of neuromuscular junctions with the neuron's target, the male genitalia. These experiments are carried out, in a complementary manner, both in the animal and in isolated cells in culture. A multi-faceted approach, involving embryological perturbations and electrophysiological, anatomical and immunocytological techniques, will be employed in this project. Further detailed study of these fundamental problems in the simple nervous system of the medicinal leech will provide valuable insights applicable to the study of both normal and abnormal development of more complex systems.