Peripheral pathways are pioneered by an array of central and peripheral neurones in grasshopper embryos
Peripheral pathways are pioneered by an array of central and peripheral neurones in grasshopper embryos
复制标题
外周通路是由蚱蜢胚胎中的一系列中枢和外周神经元开创的
作者：
R. Ho;C. Goodman
在胚胎发育过程中，神经元生长锥沿着沿着定型的通路穿越长距离到达它们适当的靶点。自从Harrison的最初观察以来，越来越多的证据支持这样的观点，即轴突通路在发育早期是“开拓性的”，当时距离很短，地形相对简单;因此，轴突支架被竖立起来，后来的神经元可以在上面导航。蚱蜢胚胎已经成为一个有吸引力的准备，研究寻路，因为神经系统是相对简单的，和个别识别的神经元在外周和中枢神经系统（CNS）的胚胎是大的，高度可访问的。外周神经和中枢神经系统之间的第一条轴突通路是如何建立的？贝特描述了肢芽中的一对细胞和触角中的两对细胞，他们被认为建立了从外周到中枢神经系统的数百微米距离的第一条外周通路;他称这些细胞对为“先驱神经元”。柯氏石证实了这一发现，并描述了第二对在肢芽中的先驱者。我们在这里报告了使用单克隆抗体（称为I-5）对蚱蜢胚胎中的外周寻路进行的进一步分析，该单克隆抗体对负责建立第一条路径的细胞进行染色5，6。与早期的报道相反，我们发现了一个大阵列的周边细胞负责建立第一个途径，与探路者和地标细胞间隔很短的时间间隔沿着的路线。此外，生长锥从中央运动神经元作出重要贡献的第一周边pathways 6。
During embryonic development, neuronal growth cones traverse long distances along stereotyped pathways to arrive at their appropriate targets. Since Harrison's initial observations1, increasing evidence has supported the notion that axonal pathways are “pioneered” early in development when the distances are short and the terrain relatively simple; thus an axonal scaffold is erected upon which later neurones can navigate. Grasshopper embryos have emerged as an attractive preparation in which to study pathfinding because the nervous system is relatively simple, and the individual identified neurones in the periphery and central nervous system (CNS) of the embryo are large and highly accessible. How are the first axonal pathways established between the periphery and CNS? Bate2 has described a single pair of cells in the limb buds, and two pairs in the antennae, which were thought to establish the very first peripheral pathways over distances of several hundred micrometres from the periphery to CNS; he called these pairs of cells ‘pioneer neurones’. Keshishian3 confirmed this finding and also described4 a second pair of pioneers in the limb buds. We report here a further analysis of peripheral pathfinding in the grasshopper embryo using a monoclonal antibody, called I-5, which stains the cells responsible for establishing the first pathways5,6. In contrast to the earlier reports, we find a large array of peripheral cells responsible for establishing the first pathways, with both pathfinders and landmark cells spaced at short intervals along the route. Furthermore, growth cones from central motoneurones make important contributions to the first peripheral pathways6.