Photoreceptor layer composition in the retina of the frog (Rana esculenta).

Retinas of Rana esculenta frogs were studied by light and electron microscopy in order to establish the photoreceptor layer composition. We found 56% red rods, 9% green rods, 19% single cones, and 16% double cones. This work provides the morphological basis for electrophysiological investigations concerning the mass receptor potential of isolated Rana esculenta retinas.