Abstract
Morphological subclasses of cone bipolar cells in the cat retina were studied in Golgi preparations and through the combination of Golgi impregnation with quantitative electron-microscopic autoradiography of 3H-glycine accumulation. Camera lucida drawings, computer-assisted rotations, and radial sections provided the morphological details used in assigning individual cells to morphologically defined subclasses. Selected Golgi-impregnated cells from retinas preloaded with 3H-glycine were sectioned for autoradiographic analysis. Grain densities were quantitated and compared on a normalized scale with the labeling of amacrine cells with 3H-glycine. Eleven types of cone bipolar cells were identified, 6 with axon terminals ramifying in sublamina a and 5 with axons terminating in sublamina b. Of these cells, types CBb2 and CBb5 showed the highest affinity for glycine, with labeling at 41 and 38% with respect to the most heavily labeled amacrine cells. Types CBb1, CBb3, CBa2, and CBa6 were labeled at approximately 20% of maximal labeling. The accumulation of glycine by these cells suggests that they may be involved in providing inhibitory input to the inner retina.