Fig. 1. BMS493, a retinoid antagonist, treatment impairs hindbrain development in a stage-dependant manner. Dorsal view of whole-mounts (a-c,g-k,m-q) or flat-mounted hindbrains (d-f,l) of control (h,I,k,n) and antagonist-treated (5x10-6 M) chick embryos at stage 5 (a,j,k), stage 6 (b,m), stage 6+ (c-e,n), stage 7 (f), stage 7+ (g), stage 8- (p) and stage 9 (q). The embryos were collected after approximately 24 hours of culture and the expression of Krox-20 (a-d,f-h, stage 11), MafB/kr (e,i,j, stage 9), Hoxb1 (k-n, stage 11) and follistatin (o-q, stage 12) was analysed. Stages indicated at the bottom-right of the pictures correspond to the stage of treatment. s1, first somite; s6, sixth somite; r4-r7, rhombomeres 4 to 7.
