Triphasic Chromaticity-Type Horizontal Cells Selectively Contact Short Wavelength-Sensitive Cone Photoreceptors in the Retina of a Cyprinid Fish, Rutilus rutilus

Light and electron microscopic characteristics of horizontal cells generating triphasic chromaticity-type light-evoked responses were studied following intracellular recording and staining with horseradish peroxidase in cyprinid fish (roach) retinae. The cellular morphology of the cells was found consistently to correspond to the H3 category of horizontal cells described previously in goldfish. Ultranstructural examination of the cone pedicles containing the stained horizontal cells' dendritic profiles revealed selective contacts with short wavelength-sensitive cone photoreceptors. The results support the feedback cascade model of horizontal cell chromatic connectivity in the cyprinid fish retina.