Six S-cone terminals are identified by their connections with 12 S-cone ON bipolar cells. A, This map, derived from Tsukamoto et al. (1992), represents a hypothetical horizontal section through the base of the cone terminals, reconstructed from 319 serial, vertical sections of 0.09 μm thickness. We identified all of the bipolar cells that are postsynaptic to the 118 shaded terminals. With five exceptions, each cone terminal contacts a pair of midget bipolar cells, one ON and one OFF. The five exceptional terminals (bold outlines) do not contact ON midget bipolar cells; instead, they contact S-cone ON bipolar cells. The terminal with the dashed contour is only partially contained within the series so we cannot determine whether it contacts an ON midget bipolar cell; this terminal is identified as that of an S cone on the basis of its contacts with S-cone ON bipolar cells. One ON midget bipolar cell is two headed and is shared by two L/M cones. B, The six S-cone terminals (white outlines) contact 12 S-cone ON bipolar cells (colored wire-frame reconstructions). The S-cone ON bipolar cell dendrites that are within the series receive synapses exclusively from S cones. This figure is modified from Herr et al. (2003), their Figure 8.