Immunostaining shows the expression of iNOS, nNOS, and eNOS (green) in control (B,F,J) and diabetic (D,H,L) retinas. DAPI staining (red) shows cell nuclei in control (A,E,I) and diabetic (C,G,K) retinas. iNOS expression in the ONL, IPL and GCL of diabetic retinas (D) is raised compared to controls (B). nNOS (F,H) and eNOS (J,L) expression is unaltered in diabetic retinas. Scale bar, 20 µm.