Bullwhip cells are not immunoreactive for GABA or glycine, and CGACs are immunoreactive for GABA but not glycine. Vertical sections of the retina were labeled with antibodies to GLP1 (red; a,c,d and f) and GABA (green; b and c) or glycine (green; e and f). Arrows indicate GLP1-positive bullwhip cells that are negative for GABA or glycine, and the arrow-heads indicate a CGAC that is labeled for GLP1 and GABA. The calibration bar (50 μm) in panel c applies to panels a–c, and the bar in f applies to d–f. Abbreviations: OPL – outer plexiform layer, INL – inner nuclear layer, IPL – inner plexiform layer, GCL – ganglion cell layer.