Fig. 1. Ectopic expression of Zic2 in mouse RGCs by in utero electroporation. (A) Schematic summarizing electroporation procedures. Plasmids (blue) were microinjected into the eye cup at embryonic stages. Two or 3 days later, embryos were analyzed to visualize EGFP-targeted cells in retinal whole-mounts (right) and axons in the optic chiasm (left). (Ba) Retinal section of a E16.5 embryo co-electroporated at E13.5 with plasmids bearing the coding sequences of EGFP and Zic2. Green cells in the center of the retina are targeted cells after the electroporation process. Scale bar: 100 µm. (Bb-d) Higher magnification of the boxed area in Ba showing Zic2/EGFP-targeted cells. EGFP is visualized in green and ectopic Zic2 is visualized in red by anti-Zic2 labeling. In the merged image (d), all of the targeted cells are Zic2-positive. Scale bar: 30 µm. (C) Quantification of the proportion of cells that co-express EGFP, Zic2 or both, in embryonic retinas as compared with the total number of transfected cells after electroporation.