Retinal neurones of cyprinid fish: intracellular marking with horseradish peroxidase and correlative morphological analysis.

An isolated retinal preparation from the cyprinid fish, roach, is described, in which neurones have been labelled ionophoretically with horseradish peroxidase (HRP), and then processed in a variety of steps to provide anatomical information concerning their form, structural relationships and synaptic contacts. This includes the use of computer graphics for 3D visualisation of fine structural features and generation of views from various angles. The practical procedures that have been devised should be useful for efficient and quantitative correlation of electrophysiological and morphological properties of retinal neurones.