Midbrain dopaminergic neurons are reduced in Uncx4.1−/−embryos. (A-D) Compared with control, tyrosine hydroxylase (TH)-positive neurons are reduced in Uncx4.1−/− embryos at E11.5 (A-B) and E17.5 (C-D). (E-N) Immunohistochemistry (IHC) reveals a reduced expression of dopamine transporter (DAT) (E-F), Pitx3 (G-H), Nurr1 (I-J) Calbindin (K-L) and Calretinin (M-N) in Uncx4.1−/− embryos compared to control. (O-P) In situ hybridization (ISH) using a probe against Otx2 shows that the expression of Otx2 is reduced in Uncx4.1-deficient mice compared to control. (Q, R) Quantification of TH-, Pitx3-, Calbindin- and Calretinin-positive cell numbers in the ventral midbrain of Uncx4.1-deficient and control embryos. Error bars represent the standard deviation. P values <0.05 were assessed as statistically significant. E, embryonic day; SN, substantia nigra; vMB: ventral midbrain, VTA, ventral tegmental area.