Effects of RA on rod and cone opsin expression. Panels show lateral views of whole-mounted eyes from DMSO-treated zebrafish embryos (A, C, E, G) or embryos treated with RA (B, D, F, H) at 51 hpf and fixed at 75 hpf. Embryos were hybridized with rod opsin riboprobes (A and B), red cone opsin riboprobes (C and D), blue cone opsin riboprobes (E and F), or UV cone opsin riboprobes (G and H). v, ventral (for all panels); scale bar = 40 μm; * indicates slight damage to eye tissue during processing.

Whole mount double immunocytochemistry using a combination of the zpr-1 (red/green cones) antibody (green fluorescence) and a blue cone opsin antibody (red fluorescence). Regions of whole mounted eye from DMSO-treated control embryos (A) and from RA-treated embryos (B), showing cells stained by each antibody. Embryos were treated at 51 hpf and fixed at 75 hpf. Scale bar = 10 μm.

Sectioned zebrafish embryo eyes processed for immunocytochemistry with an anti-RALDH2 (dorsal retinal RA synthesizing enzyme) antibody (red fluorescence). Embryos were fixed at 45 hpf (A), 52 hpf (B), and 80 hpf (C). The antibody labels neuroepithelial cells (large arrowheads) and a few developing neurons, including photoreceptors (arrows), in dorsal retina. At 52 and at 80 hpf, some staining is also evident in ventral retina, throughout the RPE (small arrowheads), and in extraocular locations. v, ventral (in all panels); scale bar = 40 μm.

Sectioned eyes derived from embryonic zebrafish, transgenic for a RARE-driven YFP transgene. Embryos were fixed at 45 hpf (A), 52 hpf (B and E), 65 hpf (C and F), and 80 hpf (D and G). (A–D) Immunocytochemistry using an anti-GFP antibody (red fluorescence) shows that neuroepithelial cells (large arrowheads) and a few developing neurons in marginal regions, as well as the RPE (small arrowheads), express the transgene and are therefore likely influenced by RA signaling. Labeling in the dorsal retina decreases after 52 hpf. (E–G) Double immunocytochemistry using the anti-GFP antibody and the zpr-1 (red/green cones) antibody (green fluorescence). Colocalization of the two antibodies (yellow fluorescence) was found in a few ventral photoreceptors at 52 hpf and 80 hpf (arrows). v, ventral (in all panels); scale bar = 40 μm.