Fig. 4. Selective expansion of the mesDA domain in Otx2-overexpressing embryos. (A-O) Immunohistochemistry and in situ hybridization performed on adjacent sections through the intermediate mesencephalon of E10.5 tOtx2^bov/+, En1^Cre/+; tOtx2^ov/+ and En1^Cre/+; tOtx2^ov/ov embryos with Otx2 and Lmx1b (A,F,K), Nkx6.1 and Shh (B,G,L), Nkx2.2 and Shh (C,H,M), Nkx2.2 and Foxa2 (D,I,N) antibodies, and Wnt1 probe (E,J,O). The arrow indicates the dorsal border of Lmx1b expression, which is adjacent to the ventral border of Nkx6.1 and the arrowhead indicates the dorsal border of Shh, which is adjacent to or slightly overlapping the ventral border of Nkx2.2. Abbreviations: rp, roof plate.