Cytochrome oxidase in rat ocular tissues with special reference to copper.

The localization of cytochrome oxidase, one of the copper metalloenzymes, was determined histochemically and compared with that of copper. Copper and cytochrome oxidase coexisted in the corneal epithelium and endothelium, iris, ciliary body, lens epithelium, and retinal photoreceptor inner segment. In spite of the presence of copper, no cytochrome oxidase was demonstrated histochemically in the retinal pigment epithelium, choroid, sclera, or optic nerve. The coexistence of copper and cytochrome oxidase suggests that copper plays a role in this copper metalloenzyme, while the non-coincidence of localizations of copper and cytochrome oxidase may be attributed to histochemical problems or to some unknown function of copper.