Fig. 3. Correct specification of mesDA neurons in Ngn2 mutants. In wild-type mice, the two major mesDA neuron subtypes, the SN and VTA neurons, are characterized by their expression of Girk2 (in SN DA neurons) and calbindin (in VTA DA neurons). (A-L) In postnatal Ngn2 mutant mice (D,E), double-stained sections showed that the expression of calbindin (red, E,F) in the Th-positive VTA neurons (green) was similar to that seen in wild-type mice (B,C), and Girk2 (red, K,L) was expressed in Th-positive SN neurons (green) in a pattern indistinguishable from that of wild type (H,I). (M-R) The expression of Pitx3 (red) was maintained in all Th-positive neurons (green) in Ngn2 mutants (R). Scale bars: 100 µm.