Fig. 2. Exogenous Lmx1a induces ectopic roof plate in the chick developing spinal cord. Expression of MafB (A-E), Msx1/2 (G-K) (both red), Gdf7 (L,M), Bmp4 (N,O), and Wnt1 (P,Q) (all blue) in unelectroporated embryos (A,G,L,N,P) and embryos electroporated with either Lmx1a-IRES-EGFP (B,H,M,O,Q) or EGFP alone (D,E,J,K). All pictures are from stage-24 embryos, 48 hours after electroporation Arrowheads point to ventral boundary of ectopic domains of expression of roof plate markers induced by exogenous Lmx1a. (F) Quantitative analysis of dorsal MafB-positive cells in embryos electroporated with Lmx1a and EGFP alone. (R-U) Expression of MafB (red) and Pax7 (blue) (R,T) or MafB and Pax7 together with GFP (green) (S,U) in intermediate neural plate explants (I.E.), electroporated with Lmx1a-IRES-EGFP (T,U) or EGFP alone (R,S). (V) Quantitative analysis of MafB/Pax7 double-positive cells in intermediate explants electroporated with Lmx1a and EGFP alone.