Fig. 2. Nkx2.1+/Th+ hypothalamic DA neurons are generated from Nkx2.1+/Shh+ progenitors in the lateral tuberal hypothalamus. (A,B) Transverse sections through embryonic day 6 (E6) tuberal hypothalamus (shown in A'), immunolabelled with Th (green) (A), Shh (red) (B) or both (B'). Th and Shh show extensive overlap. Blue shows DAPI counterstain. (C-F) Fate mapping of germinal zone of lateral tuberal hypothalamus. (C) Schematic, showing DiI labelling at stage 15. (D-F) Transverse sections through DiI-labelled embryos, fixed immediately (D) or developed to E6 (E,F). Immunolabelling with anti-Shh confirms that lateral tuberal cells are targeted at stage 15 (arrow, D) and remain in situ at E6 (arrow, E). Immunolabelling with anti-Th shows that DiI-labelled cells (red) co-label with anti-Th antibody (green; arrows in F). (G-I) Transverse sections through E6 tuberal hypothalamus, immunolabelled with Th (green) and Nkx2.1 (red) (G,H) or Th (red) and Lim1 (green) (I). Many Th+ neurons co-express Nkx2.1. Likewise, extensive co-expression of Th and Lim1 is detected. (J-L) Confocal image showing overlapping expression of Nkx2.1 and Msx1 in the lateral tuberal hypothalamus. Scale bars: 140 µm in A,B,G; 60 µm in D; 120 µm in E; 20 µm in F; 30 µm in H; 25 µm in J-L.