Figure 2.

Retinal histology in Nrl^+/b2 and Nrl^b2/b2 mice. A, Retinal histology in 3-month-old mice. The ONL in Nrl^+/b2 mice contains cones (large nuclei with dispersed chromatin) and rods (smaller, denser nuclei) in the same proportions as +/+ mice. Nrl^b2/b2 mice, like Nrl^−/− mice, lack rods, have excess cones, and also display ONL folding and shortened outer segments (OS). INL, Inner nuclear layer; IPL, inner plexiform layer; IS, inner segments; OPL, outer plexiform layer. B, Higher magnification from images in A indicating cone nuclei (arrowheads) and a representative rod nucleus (r) in a +/+ mouse. Nrl^b2/b2 mice possess only cone-like nuclei. Scale bars: A, B, 20 μm. C, Counts (mean ± SD) of cone and rod nuclei in ONL fields, determined on 3-μm-thick plastic sections like those in A. Fields avoided grossly folded areas in Nrl^b2/b2 mice. Gray triangle, Retinal pigmented epithelium.