Fig. 2. Ectopic Nkx2-2 is sufficient to repress the mDA neuronal fate and to induce rostral 5HT neurons in the ventral midbrain. (A) Fluorescent immunostaining for Otx2 (red), Nkx2-2 (green), Shh (red), Th (green) and 5HT (green), or in situ hybridization with Wnt1 probe on coronal sections of wild-type, conditional En1^+/Cre; Otx2^flox/flox, Nkx2-2^-/- single and compound En1^+/Cre; Otx2^flox/flox; Nkx2-2^-/- triple mutant mouse embryos at E12.5 (n=3 for each genotype). Wnt1 expression in the dorsal midline (RP) of the midbrain remained unaffected in all mutants (white arrows). (B) Schematic drawing of a cross-section through the ventral midbrain of E12.5 wild-type mouse embryos summarizing our results.