Palka J, Schubiger M, Ellison R L
Dev Biol. 1983 Aug;98(2):481-92. doi: 10.1016/0012-1606(83)90377-9.
We have analyzed the growth of axons in the wings of the mutants Hairy wing and hairy of Drosophila melanogaster. These mutants produce many supernumerary bristle organs and sensilla campaniformia, whose axons grow between the two wing epithelia and can be visualized in both pupal and adult stages. The sensory axons of wild-type animals follow two paths in the wing, within longitudinal veins L1 and L3, and always grow with a distal to proximal polarity. In the mutants, all axons following these two paths likewise grow with correct polarity. Axons elsewhere in the wing, however, are found to grow in many different directions, including from proximal to distal and hence directly away from the central nervous system. A variety of patterns of axon growth and fasciculation are seen in different individuals. Only if the supernumerary axons encounter the two normal paths do they reliably grow toward the base of the wing. We conclude that these two paths provide polarity information for axon growth, information which is either not used or not available elsewhere in the wing in spite of the obvious morphological polarization of every epithelial cell. The time course of neural differentiation suggests that the normal sensory cells of mutant wings, which grow axons relatively early, may be the source of polarity information for the later-differentiating supernumerary cells.
我们分析了果蝇黑腹果蝇突变体“多毛翅”和“多毛”翅膀中轴突的生长情况。这些突变体产生许多额外的刚毛器官和钟形感器，其轴突在两个翅膀上皮之间生长，并且在蛹期和成虫期都可以观察到。野生型动物的感觉轴突在翅膀中沿着两条路径生长，即在纵脉L1和L3内，并且总是以从远端到近端的极性生长。在突变体中，沿着这两条路径的所有轴突同样以正确的极性生长。然而，在翅膀其他部位的轴突被发现以许多不同的方向生长，包括从近端到远端，因此直接远离中枢神经系统。在不同个体中可以看到各种轴突生长和束状化模式。只有当额外的轴突遇到这两条正常路径时，它们才可靠地向翅膀基部生长。我们得出结论，这两条路径为轴突生长提供极性信息，尽管每个上皮细胞都有明显的形态极化，但翅膀其他部位要么不使用要么没有这种信息。神经分化的时间进程表明，突变体翅膀中相对较早生长轴突的正常感觉细胞可能是后来分化的额外细胞极性信息的来源。
