All images show dorsal views of the epithalami of wild-type or sox1a mutant embryos with expression of Tg(foxD3:GFP)zf104 and Tg(flh:eGFP)U711 transgenes (green) in the pineal (p) and the parapineal (pp). mRNA expression of genes indicated is shown in magenta. (A–B) Time-course of parapineal migration in Tg(foxD3:GFP);(flh:eGFP) (A) and sox1a-/- Tg(foxD3:GFP);(flh:eGFP) (B) embryos. Note the absence of sox1a mRNA in the parapineal cells of the sox1a-/- mutants. (C–D) otx5 (pineal and parapineal) and gfi1ab (parapineal) mRNA expression in wild-type and sox1a-/- mutant embryos at 50 hpf. (E) Efferent parapineal projections to the left dHb in wild-type and sox1a mutant embryos at 4 dpf. Note the stunted projection arising from the sox1a-/- parapineal (arrow). Scale bars 25 µm.