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 神经发生、分化和选择性突触形成。 这一目标 是通过研究中枢神经的各个区域 系统，以及这些区域内的神经细胞，在形态上变得 在发育过程中， 以履行专门职能。 神经节神经系统 选择药用水蛭进行这些实验是因为它的巨大 简单性，研究单个神经元的可能性 反复地，以及胚胎和胚后的 实验操作的阶段。 这个项目有两个部分。 第一部分涉及 一个非常基本的问题， 由外周器官调节。 它包括研究一种相互作用 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， 这些神经细胞中一个特殊群体的诞生和分化 神经节 所提出的实验旨在回答 问题（1）互动究竟是什么时候发生的？(2)是 由神经系统或目标定义的相互作用时间 纸巾？以及（3）哪些细胞是感应信号的源， 将其运送到中枢神经系统， 信号？识别参与此过程的细胞成分 互动是未来探索的必要前提， 这种相互作用的分子机制。 本项目的第二部分涉及另一个基本问题： 突触连接形成的选择性是如何实现的。 它 包括全面检查 确定运动神经元和外周组织，导致 与神经元的目标，即男性，形成神经肌肉接头 生殖器 这些实验是以互补的方式进行的， 无论是在动物中还是在培养的分离细胞中。 一个多方面的方法，包括胚胎学的扰动， 电生理学、解剖学和免疫细胞学技术， 在这个项目中使用。 进一步深入研究这些基本 药用水蛭简单神经系统的问题 适用于正常和异常研究的宝贵见解 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.