Fig. 8. Dlx3b and Sox9a crossregulate each other's expression in the otic placode. (A,B) dlx3b (blue) and sox9a (red) colocalize in the presumptive otic placode at the four-somite stage as shown with brightfield (A) and fluorescence (B) optics. sox9a is also expressed in presumptive rhombomere 4. (C,D) dlx3b expression is reduced in the otic placode after injection of sox9a-MO (30/37 embryos). (E,F) sox9a expression (blue) is reduced in the otic placode after injection of dlx3b-MO (44/50 embryos). pax2a expression is shown in red. (G,H) sox9b-MO produces a very slight reduction in sox9a expression in the otic region (15/18 embryos). (I,J) sox9b expression is significantly reduced by dlx3b-MO plus dlx4b-MO injection (16/18 embryos). We observe a similar reduction in sox9b expression in Df^b380 mutants (not shown). Expression of egr2 (krox20) in red indicates the locations of rhombomeres 5 and 6. Four-somite stage (11 h). Dorsal views, anterior towards the left. Scale bar: 100 µm in A-F.