Figure 7. TH⁺ (tyrosine hydroxylase immunopositive) cells have glutamatergic, not GABAergic signatures. The nine panels show nine TH⁺ cells from a single rabbit retina (A-I), probed for TH, glutamate and GABA in serial 200 nm sections. Each panel shows four mappings: upper left TH (yellow) + glutamate (blue), upper right TH (yellow) + GABA (red), lower left glutamate alone (cyan), lower right GABA alone (yellow). The location of each TH⁺ cell is circled. Each TH⁺ cell has a glutamate signal higher than the surrounding amacrine cell somas and equivalent to that of a ganglion cell. TH⁺ cells have no measurable GABA signal. Scale, 10 μm.