A Study on the Origin of Intraretinal Action Potential of the Cyprinid Fish by Means of Pencil-Type Microelectrode

Pencil-type microelectrodes consisting of a superfine inner pipette and a Ringer-filled outer pipette (5μ) were applied to the retina of the Cyprinid fish (Cyprinus auratus) to record the intraretinal action potentials (EIRG's).2. The configuration of the EIRG was typical of Svaetichin's cone action potential. The depth for maximal EIRG's was 80-90μ from the vitreous side and 160-170μ from the distal tips of rods, and appeared histologically to be proximal to the receptors.3. When an electrode was used with its inner pipette protruded a fixed length out of the tip of the outer pipette, both pipettes recorded similar EIRG's depending upon the depth of their insertion into the retina. With a tip distance of less than 30μ, the simultaneously recorded EIRG's through both pipettes were usually so identical that it was difficult to obtain their separate tracings.4. It was concluded that the EIRG has its main origin in a retinal layer proximal to the receptors and that the recording of the EIRG may not be intracellular.