Doniach T, Phillips C R, Gerhart J C
Department of Molecular and Cell Biology, University of California, Berkeley 94720.
Science. 1992 Jul 24;257(5069):542-5. doi: 10.1126/science.1636091.
It has long been thought that anteroposterior (A-P) pattern in the vertebrate central nervous system is induced in the embryo's dorsal ectoderm exclusively by signals passing vertically from underlying, patterned dorsal mesoderm. Explants from early gastrulae of the frog Xenopus laevis were prepared in which vertical contact between dorsal ectoderm and mesoderm was prevented but planar contact was maintained. In these, four position-specific neural markers (engrailed-2, Krox-20, XlHbox 1, and XlHbox 6) were expressed in the ectoderm in the same A-P order as in the embryo. Thus, planar signals alone, following a path available in the normal embryo, can induce A-P neural pattern.
长期以来，人们一直认为脊椎动物中枢神经系统的前后（A-P）模式仅由来自下方有模式的背侧中胚层垂直传递的信号诱导胚胎背侧外胚层形成。制备了非洲爪蟾早期原肠胚的外植体，其中背侧外胚层和中胚层之间的垂直接触被阻止，但平面接触得以维持。在这些外植体中，四种位置特异性神经标记物（engrailed-2、Krox-20、XlHbox 1和XlHbox 6）在外胚层中以与胚胎相同的A-P顺序表达。因此，仅平面信号沿着正常胚胎中可用的路径，就可以诱导A-P神经模式。
