Immunocytochemical staining of fresh frozen rhesus monkey retinas was performed using indirect immunofluorescence and immunoperoxidase (avidin-biotin-complex). Affinity-purified antibodies to interphotoreceptor retinoid-binding protein (IRBP) obtained from rabbits was used to localize IRBP on frozen sections. Fresh frozen pineal glands from the same species were stained by the avidin-biotin-peroxidase method. In addition, retinas from rod-dominant and cone-dominant species were examined. Immunocytochemical staining revealed localization of IRBP in the interphotoreceptor space of peripheral equatorial and posterior retina, with marked decrease in staining in the fovea. A transition zone was noted at the ora serrata, where staining was present in the peripheral retina up to the ora serrata, but was absent in ciliary epithelium. Cone-dominant retinas (chick and turtle) showed lack of reactivity to IRBP. Rod-dominant rat retina showed localization of IRBP to the interphotoreceptor space. Primate and rat pineal showed immunocytochemical localization of IRBP.
