Figure 11.

K_v2.1^−/− rods undergo slow degeneration. (A) Paraffin-embedded ultrathin sections of heterozygous and Kv2.1^−/− retinas of 6-mo-old mice stained for hematoxylin and eosin. Sections have been aligned at the ELM, showing that the OS, IS, and ONL layers are smaller in the K_v2.1^−/− mouse. Scale bar, 10 µm. (B) OCT B-scans of central retina of K_v2.1^−/− mice at 6 wk and 24 wk of age. There is a notable decrease in the OS, IS, and ONL layer thickness over time in K_v2.1^−/− mice. Scale bar, 100 µm. (C) Quantification of the OS, IS, ONL, and IPL layers in the same mice from 6 wk to 6 mo of age (mean ± SEM, n = 4 per genotype). The OS layer is shorter in K_v2.1^−/− mice at all ages, and there is a progressive decline in IS and ONL thickness over time. (D) TEM sections showing individual rod photoreceptors in WT and K_v2.1^−/− mice. Mitochondria in the K_v2.1^−/− rod inner segments are more abundant and look distorted as compared with WT. Dark adaptation before euthanasia did not change this effect. Scale bar, 1 µm. IPL, inner plexiform layer; OPL, outer plexiform layer; GCL, ganglion cell fiber layer; TEM, transmission EM.