Fig. 5. Treatment of wild-type embryos with either retinoic acid or R115866 phenocopy the stocksteif mutant phenotype. (A) After treatment of wild-type embryos with 1 µM RA, three phenotypic classes were observed, with the most severe phenotype completely mimicking the sst mutant phenotype. (B) Results are shown for RA treatments that were started at the days indicated and continued until the embryos were fixed at 8 dpf. Control treatments with only DMSO were started at day 4. (C) Treatment of wild-type embryos with 0.5 µM R115866 resulted in the same three phenotypic classes as shown for the RA treatments in A.