一、前　言远在 Golgi和 Cajal时代 ,追踪神经元之间的联系即已是神经解剖学研究中的重大目标 ,它对研究神经的功能、神经系统的发育和成熟都具有重要的价值。这种方法学的建立始于 19世纪末的逆行和顺行溃变的研究。逆行溃变主要是指毁损轴突后神经元胞体 (即去除其靶区之后的 I. INTRODUCTION Far in the Golgi and Cajal era, tracing the connections between neurons is already a major goal in neuroanatomical studies. It is of great value in studying the function of nerves, the development and maturation of the nervous system. The establishment of this methodology began with the study of retrograde and forward degeneration at the end of the 19th century. Retrograde degeneration mainly refers to the destruction of post-axonal neuronal soma (ie, after removal of its target region