Morphological subtyping of bipolar cells in mouse and rat. Adapted from Ghosh et al. . Shown are drawings of bipolar cells after injection with intracellular dyes. The cone bipolars are numbered 1 through 9, and the rod biolar is labeled RB. The layers of the retina are the outer plexiform layer (OPL), inner nuclear layer (INL), the inner plexiform layer (IPL) and the ganglion cell layer (GCL). The dashed line midway through the IPL represents the division above which the axons of OFF-bipolars extend and below which axons of ON-bipolars are found.