Expression patterns in key basal ganglia structures of BAC transgenic mice. (A) Drd1a-EGFP, (B) Drd2-EGFP, and (C) Drd1a-tdTomato BAC lines. Fluorescence was most prominent in striatal soma and axonal projections. Scale bar, 1 mm. Other abbreviations: GPe, globus pallidus externa; SNr, substantia nigra pars reticulata; Str, striatum. Reproduced with permission from [243].