Chien C B, Rosenthal D E, Harris W A, Holt C E
Department of Biology, University of California, San Diego, La Jolla 92093-0322.
Neuron. 1993 Aug;11(2):237-51. doi: 10.1016/0896-6273(93)90181-p.
We have developed an exposed brain preparation for observing growth cone pathfinding behavior while performing in vivo pharmacological manipulations, and we used it to test whether Xenopus retinal growth cones need filopodia to navigate. Time-lapse video observation showed that cytochalasin B acted quickly and reversibly when applied; cytochalasin B-treated growth cones lacked filopodia, but had active lamellipodia and continued to advance slowly. Whereas normal retinotectal axons visualized with horseradish peroxidase turn caudally in the mid-diencephalon to reach the tectum, cytochalasin B-treated axons grew past the normal turning point and, instead, continued straight within the diencephalon. In dose-response experiments, pathfinding became abnormal in the same concentration range in which filopodia disappeared. These results suggest that filopodia are necessary for retinal growth cones to respond to guidance signals in the diencephalon.
我们开发了一种暴露脑的制备方法，用于在进行体内药理学操作时观察生长锥的路径寻找行为，并用它来测试非洲爪蟾视网膜生长锥是否需要丝状伪足来导航。延时视频观察显示，细胞松弛素B应用后作用迅速且可逆；经细胞松弛素B处理的生长锥缺乏丝状伪足，但有活跃的片状伪足并继续缓慢前进。用辣根过氧化物酶可视化的正常视网膜 - 脑顶盖轴突在中脑间脑处转向尾侧以到达脑顶盖，而经细胞松弛素B处理的轴突越过正常转折点，而是在间脑内继续直行。在剂量反应实验中，在丝状伪足消失的相同浓度范围内路径寻找变得异常。这些结果表明丝状伪足对于视网膜生长锥响应间脑的引导信号是必要的。
