Fig. 7.

Fgf8a and Tbx2b act additively in the formation of parapineal cells, whereas Fgf8a acts downstream of Tbx2b to prevent the formation of cone photoreceptors. (A-D) Dorsal views of uninjected (NI) WT (A), uninjected fgf8a^x15 mutant zebrafish larvae (B), WT injected with tbx2b^MO (C) and fgf8a^x15 mutant embryos injected with tbx2b^MO (D) at 96 hpf, labeled for gfi-1.2 to mark parapineal cells (arrowheads). (E) Many fewer parapineal cells are detected when tbx2b and fgf8a are simultaneously reduced than when either is singly depleted (^**P<0.005, ^***P<0.0005). (F-I) Dorsal views of confocal slices of WT;NI (F), fgf8a^x15;NI (G), WT;tbx2b^MO (H) and fgf8a^x15 ;tbx2b^MO (I) larvae labeled with foxd3:GFP to mark the entire pineal complex and Arr3a to mark cone photoreceptors. (J) Tbx2b depletion reduces the number of cone photoreceptors to a level indistinguishable from non-injected WT and tbx2b morphants (^***P<0.0005). Error bars represent s.e.m. Scale bars: 25 μm.