Fig. 9. The residual otic cells that form in Df^b380 mutants require Fgf3 and Fgf8 signaling. (A,B) Loss of dlx3b, dlx4b and sox9a function in Df^b380 mutants results in formation of only a few residual otic cells, as indicated by pax2a expression, that form a small epithelial ball (19/44 Df^b380 embryos). (C) Injection of fgf3-MO into Df^b380 mutants further reduces the number of otic cells, but the residual cells still form an epithelial-like structure (9/21 embryos). (D) Df^b380;fgf8^– double mutants lack all detectable otic cells (11/11 embryos). (E,F) fgf8^– mutants form a somewhat variably smaller but otherwise fairly normal otic vesicle. (G) Injection of fgf3-MO into wild-type embryos results in a small and somewhat disorganized otic vesicle. (H) Injection of fgf3-MO into fgf8^– mutants results in a very reduced number of disorganized otic cells (25/26 embryos). More than half of the injected embryos form a relatively large placode or vesicle-like otic mass (not shown), suggesting a less severe otic phenotype compared with fgf8^– mutants injected with fgf3-MO. Prim-5 (24h). Side views, anterior towards the left, dorsal towards the top. Scale bar: 25 µm.