Norgestrel-supplemented diet significantly protects against photoreceptor cell death out to P40 in the rd10 retina.

(A) Apoptosis of retinal cells was detected by terminal dUTP nick end-labeling (TUNEL; green & greyscale) of DNA strand breaks in cell nuclei. Norgestrel treatment (NORG diet) decreased TUNEL-positive staining in the central P15 and P20 retina compared to control mice (Control diet). N = 3 mice per group. Hoechst (blue) staining reveals the cell layers in the retina. Scale bar 50μm. (B) Quantification of outer nuclear layer (ONL) thickness in the central and peripheral retina. N = 3 mice per group, n = 20 sections per mouse. Results are presented as mean ± SEM (t-test, *p<0.05, **p<0.01, ***p<0.005).