Figure 5

Role of p21 in hypoxic preconditioning. Hypoxic preconditioned (hypoxia) or normoxic (normoxia) p21^-/- mice were exposed to 13'000 lux of white light for 2 hours and retinal morphology was analyzed 10 days thereafter. Dark-adapted knockout mice served as controls (dark control). Hypoxic preconditioning almost completely protected the retina of p21^-/- mice leading to a retinal morphology indistinguishable from controls. Exposure of normoxic mice led to a complete degeneration of photoreceptors in the central retina. Shown are representative samples of control and light exposed mice. n = 2 (controls); n = 4 (light exposed mice). Abbreviations as in Fig. 1. Scale bar: 25 μm.