Fig. 2. Changes in retinoids in response to light or dark adaptation in the isolated retina. Adult chicken eyes were dark adapted for 4 h, and retinae were dissected free of the retinal pigment epithelium (RPE) prior to exposure to light (2500 lux) for 0.5 h, and for 1 h in vitro. Retinoids were extracted and analyzed by HPLC. Means ± S.E.M.. were calculated from results of two experiments. For each of the two experiments, retinoid extracts from pooled retinae from 4-6 eyes per treatment group were analyzed by HPLC.