RA inhibits primitive erythropoiesis in WT zebrafish embryos. Dorsal view of flat-mounted 5-ss wild-type AB embryos. Head is oriented to the left, posterior embryo to the right. Higher power view in the bottom panels is indicated by the boxed region in the top panels. Representative embryos are shown from a single experiment. Similar results were obtained from 2 other replicate experiments. (A-D) Whole-mount in situ hybridization for scl expression in embryos treated with increasing concentrations of RA from 90% epiboly until 5 ss. (E-H) Whole-mount in situ hybridization for gata1 expression in embryos treated with increasing concentrations of RA from 90% epiboly until 5 ss. All embryos are fixed at 5 ss.