Fig. 9. A summary of gene expression differences in the developing forebrain of cavefish and surface fish embryos. Schematic representations of lateral views of embryonic brains. The expression patterns of Shh (A), Nkx2.1a (B), Nkx2.1b (C), Lhx6 (D) and Lhx7 (E) are drawn in grey, blue, green, yellow and pink, respectively. For each gene, the dark and light colour schematises the enlarged expression domains in cavefish versus surface fish, respectively. In B to E, the Shh expression pattern, which is larger in cavefish, is also shown in grey. For each gene, the region-specific changes in expression observed in cavefish relative to surface fish embryos or after cyclopamine treatment in cavefish are indicated. The effect on Lhx6 in the hypothalamus is probably mediated through the increase of Nkx2.1a in this region, whereas the effects on Lhx6 and Lhx7 in the po and telencephalon are probably mediated through the increase of Nkx2.1b in the respective regions.