hoxa5a and hoxb5b mRNA expression. Upper panels (A, C, E, G) - whole mounts are shown in lateral views. Lower panels (B, D, F, H) - higher magnification and same orientation of area framed in A, C, E, G. Abbreviations (as above): Hr, hindbrain rhombomeres; PA, pharyngeal arch. Scale bars: 0.2 mm (A, C, E, G), 0.1 mm (B, D, F, H).