Fig. 2. Establishment of hindbrain boundaries is dependent on retinoic acid concentration. Dorsal view of whole-mounts of BMS493-treated chick embryos at stage 5 at the following concentration: 10-6 M (a,g), 5x10-7 M (b,c,j,l), 2.5x10-7 M (d), 10-7 M (e,h,m) and 10-8 M (f,i,k,n). Whole-mount in situ hybridization was performed on embryos using digoxigenin-labelled probes for Krox-20 (a-f, stage 11), Hoxb1 (g-i, stage 11), MafB/kr (j,k, stage 10) and follistatin (l-n, stage 12). s6, sixth somite. r4-r7, rhombomeres 4 to 7.
