Retinal degeneration becomes apparent in whirlin knockout mice at 28–33 months of age.

<p>(A) Representative dark-adapted ERG tracings show reduced a- and b-waves in response to a series of white light stimuli in whirlin knockout mice at this age. (B) Representative 1-µm retinal sections stained with toluidine blue show shortened OS and reduced ONL in whirlin knockout mice. Scale bars, 5 µm. (C) Representative 1-µm retinal sections stained with toluidine blue show comparable thickness of OS and ONL between whirler mice and age-matched WT (whirlin^+/+) mice. Scale bars, 5 µm. (D) Measurement of OS length and ONL thickness at different locations along the vertical meridian in whirlin knockout retinas. The number of mice measured at each location in each group is indicated above or below the lines. The error bar represents the standard error of the mean. *, p<0.05. Whirlin heterozygous littermates were used as a control in these studies. (E) Measurement of OS length and ONL thickness at different locations along the vertical meridian in whirler retinas. The numbers of mice measured at each point in whirler and age-matched wild-type cohorts are indicated below and above the lines, respectively. The error bar represents the standard error of the mean. RPE, retinal pigment epithelium; OS, outer segment; IS, inner segment; ONL, outer nuclear layer; OPL, outer plexiform layer; INL, inner nuclear layer.