Fig. 1. Assay for retinal progenitor proliferation in explants and in ovo. (A) E5.5 retinal explants electroporated with pCAG:CA-ß-catenin or pCAG:GFP were cultured for 18 hours and exposed to [³H]thymidine for 6 hours. The percentage of [³H]thymidine⁺ cells were quantified following autoradiography. Bars represent the percentage of cells labeled with [³H]thymidine among the GFP⁺ population. Error bars represent the s.d. (B,C) An in vivo assay for retinal cell proliferation using BrdU (B) and pH3 (C) in an E7.5 retinas infected with RCAS:CA-ß-catenin or RCAS:GFP. (D-F) Representative images of an RCAS:GFP-infected retina at E7.5 showing BrdU incorporation (green) and pH3 (red) in the central retina (D), the peripheral retina including the CMZ (E) and in the ciliary/iris epithelia (F). (G) Relative position of sections shown in D,E and F and used for scoring in B and C. (H) Representative image of an E7.5 retinal section showing BrdU labeling (green) and pH3 (red) in a thin and folded region induced with RCAS:CA-ß-catenin from the central part of the retina. Le, lens. Scale bar: 75 µm.