Figure 6

More retinal ganglion cells are born in albino than in pigmented retina at embryonic day 15. (A) Timeline of 5-ethynyl-2’-deoxyuridine (EdU) injections (10 am, 2 pm, 6 pm) at embryonic day (E)15 and sacrifice at E17.5. Each box represents 4 hours. All quantifications for (B-D) were carried out in the second and fourth sections rostral to the optic nerve. Ventrotemporal (VT) region defined as most peripheral 800 pixels (1 pixel = 0.3205 μm). (B) Bar graph comparing the number of Zic2⁺, Islet1/2⁺ cells in VT retina labeled with EdU in pigmented (n = 4) and albino (n = 4) retina. A similar number of Zic2⁺ RGCs are born at E15 in pigmented and albino retina. (C) Bar graph comparing the number of Zic2^-–, Islet1/2⁺ cells labeled with EdU in pigmented (n = 4) and albino (n = 4) VT retina. A significantly greater number of Zic2⁻ RGCs are born at E15 in albino retina. (D) Bar graph comparing the number of Islet1/2⁺ cells in the VT region labeled with EdU in pigmented (n = 4) and albino (n = 4) retina. The number of Islet1/2⁺ cells at E17.5 that become post-mitotic at E15 is significantly higher in VT retina of albino mice (n = 4) compared with pigmented mice (n = 4). Error bars indicate SEM. Two-tailed unpaired t-test: * P < 0.05, ***P < 0.001. N.S., not significant.