Fig. 1

mbl embryos show altered AP regionalisation of the ventral midline of the neural plate. Dorsal views of wild-type and mbl embryos with anterior on the top. In this and other figures, where indicated, stage is shown bottom left, genes analysed by in situ hybridization are shown bottom right and the experimental procedure is top right. Arrowheads point to hypothalamic (nk2.1a) gene expression. pax2.1 is used as a marker of the prospective midbrain in A-H and K-L. The asterisk indicates the prospective hypothalamic domain of reduced foxa2 expression in a wild-type embryo (C) and brackets indicate the AP length of the prospective floorplate domain rostral to the midbrain in wild-type (C,G) and mbl (D,H) embryos. The inset panel between G and H shows nk2.1a expression in the prospective hypothalamus in yellow and foxa2 in the prospective floorplate in blue. The margin of the neural plate, the hatching gland, the prospective notochord and eye field (red) are shown by dlx3, hgg1, ntl and rx3 expression domains in I,J. The mbl embryo lacks rx3 expression in the eye field. (K-L) Transplanted cells overexpressing wnt8b (brown) suppress nk2.1a expression (blue, arrowhead) and expand rostrally pax2.1 expression (white asterisk) in a wild-type host embryo. Abbreviations: tb, bud stage, e, prospective eye, hg, hgg1 expression in the prechordal plate, hy, hypothalamus, mb, midbrain, n, prospective notochord; s, somite stage; wt, wild type