The retinoid cycle is a recycling system that replenishes the 11-cis-retinal chromophore of
rhodopsin and cone pigments. Photoreceptor-specific retinol dehydrogenase (prRDH)
catalyzes reduction of all-trans-retinal to all-trans-retinol and is thought to be a key enzyme
in the retinoid cycle. We disrupted mouse prRDH (human gene symbol RDH8) gene
expression by targeted recombination and generated a homozygous prRDH knock-out
(prRDH–/–) mouse. Histological analysis and electron microscopy of retinas from 6-to 8 …