Fig. 2. Zebrafish fgf3 expression overlaps with fgf8 expression in presumptive r4. In situ hybridization of fgf3 (in blue in A-E,H) and fgf8 (in blue in F,G and pink in H). Other markers are shown in red: pax2a at the MHB (A-G); no tail in the notochord (A); and krox-20 in r3 and r5 (B-G). Anterior is towards the top (A,B,F,H) or towards the left (C-E,G). In H, only the strong fgf8 expression in r4 is detectable in the double label (compare with F). Stages are indicated (lower right-hand corners). Scale bars: 100 µm in A,C; 50 µm in B,D-H. ntc, notochord; mhb, midbrain-hindbrain boundary; r3, rhombomere 3; r5, rhombomere 5; fb, forebrain; tb, tail bud.