Math5-null mice have fewer rods. Rod photoreceptors in wild-type (A) and Math5−/− (B) retinas were immunostained with RetP1, which labels rod outer (OS) and inner (IS) segments, and perikarya in the ONL. Math5−/− have persistent hyaloid vasculature (arrow) in the vitreous.8 (C) Rod perikarya counts per field, normalized to wild-type. Scale bar, 50 μm; **P < 0.001. Error bars, ±SEM.