Fig. 1. Six3, Irx3, Gbx2, Dlx2 and Wnt3 expression in the developing forebrain. (A-J) In situ hybridization of Six3 (A,B), Irx3 (C,D), Dlx2 (E,F), Gbx2 (G,H) and Wnt3 (I,J) at HH stage 7-8 (upper panels) and HH stage 19 (lower panels). At HH stage 7-8, Six3 (A) and Irx3 (C) are anterior and posterior to the prospective zli, respectively. At this stage, Gbx2 (G) expression is confined to the prospective hindbrain, and Dlx2 (E) and Wnt3 (I) expression is negligible. At HH stage 19, the expression domains of Irx3 (D), Gbx2 (H) and Wnt3 (J) are posterior to the zli, whereas Six3 (B) and Dlx2 (F) are expressed anterior to this structure. Arrowheads indicate the position of the zli. Scale bar: 100 µm.