Fig. 5. Expression of fgf8 and fgf3 in the hindbrain. Dorsal view (anterior towards the left) of specimens double stained for Fgf gene expression (blue) and krox20 (red). Loss of krox20 staining in r5 identifies val/val mutants. (A,B) fgf8 expression at 12 h in wild-type (A) and val/val (B) embryos. Brackets indicate the r4 domain of fgf8. No change is detected in the mutant. (C,D) fgf3 expression at 12 h in wild-type (C) and val/val (D) embryos. (E,F) fgf3 expression at 14 h in wild-type (E) and val/val (F) embryo. Brackets indicate the domain of fgf3 corresponding to either r4 (C,E) or r4 to rX (D,F). fgf3 is ectopically expressed in the rX region in val/val embryos. Scale bar: 80 µm.