Figure 7. Retinal degeneration in P180 mice heterozygous or homozygous for the Rosa26-floxSTOP/SRF-VP16 transgene. Histological sections of P180 retinas are shown displaying degenerative processes in Rosa26-floxSTOP/SRF-VP16 heterozygous (het) and homozygous (hom) animals. A-C: Hematoxylin and eosin staining. Note the scattered degeneration in the posterior part of heterozygous and homozygous retinas. Peripheral regions show no degeneration. Scale bars represent 200 μM. D-F: Higher magnifications of P180 retinas are displayed. Wild-type retina (D) showing ganglion cell layer, inner plexiform layer, inner nuclear layer, outer nuclear layer, inner and outer segments and retinal pigment epithelium (RPE). Degeneration of the photoreceptor layer in adult heterozygous (E) and homozygous (F) retinas is shown. In (F), arrowheads point to regions of complete degeneration of the inner and outer nuclear layers, whereas inner nuclear layers can be found at least partially in other places (asterisks). Occasionally, even the ganglion cell layer can no longer be found (indicated by horizontal double-headed arrow). Scale bars represent 50 μM. G: Quantification of individual mice displaying retinal degeneration in histological sections. Retinas displaying areas in the outer nuclear layer with eight or fewer layers of photoreceptor nuclei were classified as having “partial retinal degeneration.” Sixty percent of the heterozygous animals and over 80% of the homozygous animals showed partial degeneration.