Fig. 1. Dorsally expressed Wnt genes regulate expression of progenitor proteins and result in cell fate changes along the DV axis. (A,B) HH stage 18 chick embryos show that expression of Wnt1 and Wnt3a is restricted to the dorsal-most neural tube. (C-G) Eight hours post-electroporation (8 hours PE) of Wnt1/3a, expression of Pax7 (C) and Pax6 (D) is ventrally expanded. Green shows GFP expression as reporter of ectopic Wnt gene expression (E). Expression of ventral Olig2 (F) and Nkx2.2 (G) is reduced. (H-Q) Twenty-four hours PE, Wnt1/3a causes overgrowth of the electroporated side, expansion of Pax7 (H) and Pax6 (I) expression, loss of intermediate genes Dbx1 (K) and Dbx2 (L), and loss of ventral Olig2 (M) and of Nkx2.2 (N), Foxa2 (O), Nkx6.2 (P) and Nkx6.1 (Q). (J) Green shows GFP expression as a reporter of ectopic Wnt expression. (R-T) Forty-eight hours PE, Wnt1/3a causes phenotype changes on differentiated neurons. (R) Quantitative analysis of Lhx1/5+/Pax2-dI2, Islet1+ dI3 and Lhx1/5+/Pax2+ dI4-dI6/V1 interneurons and of ventral Islet1+ motoneurons (MN) on Wnt1/Wnt3a electroporated versus control pCIG electroporated embryos. (S,T) Double immunofluorescence staining with specific markers for each neuronal population: Lhx1/5+/Pax2-for dI2 (red); Lhx1/5+/Pax2+ for dI4-dI6/V1 (yellow) (S) and Islet1+ for dI3 and MN (red), Pax2 for dI4-V0/V1 (green) (T).