Retinal histologic examination after 10 weeks of diabetes. Representative photomicrographs of retinal sections from a control eye (A) and a diabetic eye without (B) or with (C) pulses of ischemia. No evident alterations in retinal morphologic features were observed. Immunohistochemical detection of NeuN-positive neurons in the GCL from a control eye (D) and a diabetic eye without (E) or with (F) ischemia pulses. A strong NeuN immunostaining was confined to ganglion cells in the GCL (red). Cell nuclei were counterstained with DAPI (blue). Cell count in the GCL evaluated by hematoxylin-eosin staining, DAPI staining, and NeuN immunostaining (G). No differences in the number of cells were observed by these methods. Retinal layer thickness assessed in different groups after 10 weeks of diabetes (H). Whole retina thickness was 137.5 ± 12.3 μm, 158.2 ± 10.8 μm, and 152.0 ± 19.2 μm in control, diabetic, and diabetic with ischemia pulses groups, respectively. These values did not differ among groups. Scale bar: 50 μm (upper); 100 μm (middle). Data are the mean ± SEM (n = 5 eyes per group). IPL, inner plexiform layer; INL, inner nuclear layer; ONL, outer nuclear layer; OS, outer segments of photoreceptors.