Fig. 4. Selective loss of retinal cell subtypes in Bhlhb5-null retinas. (A-X) Sections from P21 mouse retinas were immunolabeled with subtype-specific markers (green) and nuclear-counterstained with PI (red). Loss of Bhlhb5 leads to a severe loss of amacrine cells immunoreactive for Pax6 (A,G) and GAD65 (B,H) and to an absence of TH⁺ (C,I) and Prox1⁺ (D,J) amacrine cells. There is no overt change in the number of amacrine cells immunoreactive to ChAT (E,K), calretinin (F,L) and Isl1 (M,S). A significant loss of Vsx1⁺ CB cells was observed in Bhlhb5-null retina (N,T). However, no discernible change is seen in the number of PKC⁺ RB (O,U) and Go⁺ ON-bipolar (P,V) cells, and Brn3b⁺ (Q,W) and Brn3a⁺ (R,X) ganglion cells. Scale bar: 100 µm.