Figure 6

The rhombomere 5 region is broadened in the rSey²/ rSey² hindbrain. (A-F) The expression sites of Hoxb1 and Krox20 (blue) were compared with that of Cyp26b1 (red) in WT (A, D), rSey²/+ (B, E) and rSey²/rSey² (C, F) hindbrains. (A-C) Hoxb1 expression (as a marker of r4) is unchanged in the rSey²/rSey² hindbrain (C). (D-F) Krox20 expression (as a marker of r5; cannot detect in r3 at E11.5) overlaps with Cyp26b1 expression in the dorsolateral domain of the WT and rSey²/+ hindbrain (D and E). The r5 region is slightly broadened in the rSey²/rSey² hindbrain along the anterior-posterior axis (F). (G-I) EphA4 expressed in both r3 and r5 of the E11.5 hindbrain. EphA4 expression domains (blue) are broadened only within the r5 region of the rSey²/rSey² hindbrain (I) as compared to the WT (G). (J-L) The expression site of RARβ (blue) was compared with that of Krox20 (red) in WT (J), rSey²/+ (K) and rSey²/rSey² (L) hindbrains. Krox20 expression is posteriorly expanded in the rSey²/rSey² hindbrain (L), although the anterior border of RARβ expression (anterior edge of r7 in L) is not altered. Scale bar: 500 μm.