Figure 4.

Six-month Ikbkap CKO retinas were grossly normal except for the reduction in RGCs. A, H&E staining showing control and mutant (CKO) eyes. The mutant eyes at 6 months appear normal. B, Retinal cross sections at central (>0.25 mm from ONH), middle (1 mm from ONH), and peripheral (1.75 mm from ONH) retinas in the temporal hemisphere. Retinal structure of the mutant was grossly normal, except for the reduction in cell number in the GCL that is apparent toward the peripheral retinas. C, Reduction in cell number was observed in the mutant GCL at 1 mm from the ONH (middle). Images of the temporal retina are shown. D, Mutant retinas showed reduced numbers of RGC marker, Brn3 (red). Islet1 (green) IHC showed normal cholinergic amacrine and optic nerve bipolar cells. E, Choline acetyltransferase (green) IHC showed normal number and structure of cholinergic amacrine cells. PKD2L-1 (red) IHC indicated normal photoreceptor cilia structure. F, Müller glial marker Sox9 (green), Sox2 (red), and GFAP (blue) showed normal, nonactivated Müller glia in the mutant retinas. G, Because of variability in the phenotype, degenerating mutant retinas were occasionally observed at 6 months. In these retinas, Müller glia were activated (GFAP upregulation), and photoreceptor rosettes were seen. D–G, Images represent 1 mm from the ONH at the temporal retina. Scale bars, 250 μm (A) and 50 μm (B–G).