Fig. 2. Expression of Bhlhb5 in GABAergic amacrine and OFF-cone bipolar subtypes. Sections from P28 mouse retinas were doubleimmunolabeled with anti-Bhlhb5 (red) and subtype-specific markers (green) as indicated. (A-C) The Bhlhb5⁺ cells in the GCL and the ACL are Pax6⁺ amacrine cells. (D-F) Bhlhb5 is expressed in GAD65⁺ GABAergic amacrine cells. (G-I) Bhlhb5 is co-expressed with Prox1 in displaced amacrine cells (arrows) in the GCL and bipolar cells (arrowheads) in the INL. (J-L) Bhlhb5 is co-expressed with Chx10 in bipolar cells (arrowheads). Inserts show the double-labeling of bipolar cells (asterisks) at high magnification. (M-O) All Bhlhb5⁺ bipolar cells are Vsx1⁺ cone bipolar cells (white arrowheads). (P-R) All Bhlhb5⁺ bipolar cells (white arrowheads) are recoverin⁺ Type 2 OFF-bipolar cells; red arrowheads indicate the OFF-bipolar cells immunoreactive to recoverin only. Scale bar: 50 µm.