Yamada K M, Spooner B S, Wessells N K
Proc Natl Acad Sci U S A. 1970 Aug;66(4):1206-12. doi: 10.1073/pnas.66.4.1206.
The motile tips of elongating axons consist of growth cones from which microspikes protrude. Cytochalasin B causes retraction of microspikes, rounding-up of growth cones, and cessation of axon elongation. Drug withdrawal is followed by resumption of growth cone and microspike activity and of axon elongation. In contrast, colchicine causes shortening and retraction of axons, but it does not initially affect the tips. Growth cones and microspikes of elongating axons contain a network of 50 A microfilaments, the pattern of which is altered by cytochalasin treatment. These experiments indicate that both structural integrity of the axon and continuing function of its motile tip are essential elements in axonal elongation.
正在延伸的轴突的运动性末梢由生长锥构成，微刺从生长锥中突出。细胞松弛素B会导致微刺缩回、生长锥变圆以及轴突延伸停止。药物撤除后，生长锥和微刺的活性以及轴突延伸会恢复。相比之下，秋水仙碱会导致轴突缩短和缩回，但最初并不影响末梢。正在延伸的轴突的生长锥和微刺含有一个50埃的微丝网络，细胞松弛素处理会改变其模式。这些实验表明，轴突的结构完整性及其运动性末梢的持续功能都是轴突延伸的关键要素。
