Fig. 3. CR4.2 directs GFP expression in Foxn4⁺ cells and differentiating horizontal cells.

Chick retinas were electroporated with either the control CAG-GFP construct or CR4.2-βGP-GFP (CR4.2-GFP) construct at embryonic day 4 (E4). Transfected retinas were harvested at E6, E7, and E8 during development, sectioned, and immunostained for GFP (green), Foxn4 (red, panels A–F), and Lim1+2 (red, panels G–L). (A–F) Double labeled cells (boxed regions) are shown in higher magnification on the right (indicated by arrowheads; arrows point to Foxn4-negative cells). (M,N) Quantification of double labeled cells (GFP⁺/Foxn4⁺ or GFP⁺/Lim1+2⁺). Error bars represent standard error of the mean. Data represent the mean ± s.d.; n≥3. ONBL, outer neuroblastic layer; INBL, inner neuroblastic layer; ONL, outer nuclear layer; INL, inner nuclear layer; GCL, ganglion cell layer. Scale bar: 20 µm.