Eisen J S, Myers P Z, Westerfield M
Nature. 1986;320(6059):269-71. doi: 10.1038/320269a0.
How is the adult pattern of connections between motoneurones and the muscles that they innervate established during vertebrate development? Populations of motoneurones are thought to follow one of two patterns of development: (1) motor axons initially follow stereotyped pathways and project to appropriate regions of the developing muscle or (2) motor axons initially project to some regions that are incorrect, the inappropriate projections being eliminated subsequently. Here we observed individually identified motoneurones in live zebra fish embryos as they formed growth cones and as their growth cones navigated towards their targets. We report that from axogenesis, each motor axon followed a stereotyped pathway and projected only to the specific region of the muscle appropriate for its adult function. In addition, the peripheral arbor established by each motoneurone was restricted to a stereotyped region of its own segment and did not overlap with the peripheral arbor of the other motoneurones in that segment. We conclude that the highly stereotyped pattern of innervation seen in the adult is due to initial selection of the appropriate pathway, rather than elimination of incorrect projections.
在脊椎动物发育过程中，运动神经元与其所支配肌肉之间的成人连接模式是如何建立的？运动神经元群体被认为遵循两种发育模式之一：（1）运动轴突最初沿着固定的路径延伸，并投射到发育中肌肉的适当区域；或者（2）运动轴突最初投射到一些不正确的区域，随后这些不适当的投射会被消除。在这里，我们在活斑马鱼胚胎中观察了单个被识别的运动神经元，观察它们形成生长锥以及生长锥向目标导航的过程。我们报告，从轴突发生开始，每个运动轴突都沿着固定的路径延伸，并且仅投射到与其成人功能相适应的肌肉特定区域。此外，每个运动神经元建立的外周树突仅限于其自身节段的固定区域，并且与该节段中其他运动神经元的外周树突不重叠。我们得出结论，在成体中看到的高度固定的神经支配模式是由于最初选择了适当的路径，而不是消除不正确的投射。
