Fig. 3. Non-cell-autonomous effect of ectopic Lmx1a-generated roof plate on the specification of dorsal interneurons in chick neural tube. Expression of LH2A/B (A-C), Lim1/2 (E-G) and Islet1 (H-L) in neural tubes of unelectroporated embryos (A,E,H) and embryos electroporated with Lmx1a-IRES-EGFP (B,C,F,G,I-L) (all red). All pictures are taken at stage 24, 48 hours after electroporation Arrowheads and arrows point to non-affected and affected neuronal populations, respectively. Insets show higher magnifications of boxed regions. Lim1/2 and Isl1 expressing cells in the ventral half of the neural tube are marked by `V'. (M,N) Visualization of expression of LH2A/B (red) together with GFP (green) in intermediate explants (I.E.) electroporated with Lmx1a-IRES-EGFP (N) or EGFP alone (M). (D,O) Quantitative analysis of LH2-positive cells in embryos (D) or I.E. (O) electroporated with Lmx1a and EGFP alone.