Fig. 4. Dorsal-to-ventral migration within the basal telencephalon. (A) A grafting experiment performed at E13.5, in which ventrally migrating cells are analysed. The box delineates the area shown in C-E''. (B) Example of a graft in which GFP-positive cells have reached the POa. Arrows in C show co-localization of COUP-TFI (red) with GFP (green), whereas no co-labelling with COUP-TFII (red) has been identified (D) within the migratory cells. (E-E'') Arrows in (E'') indicate that migrating cells are neurons by double labelling of GFP (green) with Tuj1 (red). (E'') is a merge of panels (E) and (E'). (F) Double immunofluorescence of COUP-TFI (green) and GABA (red) shows that some COUP-TFI-positive cells (arrows) are GABAergic in the ventral migratory stream. (G) By electroporation of a GFP-expressing construct into the MLGE region, GFP-positive cells migrate ventrally, and these cells express COUP-TFI (arrows in H). Similarly, by inserting a DiI crystal into the MLGE region, fluorescent cells are detected ventrally, in the POa/hypothalamic region (I). These cells co-express COUP-TFI (J). The arrow indicates a leading process. Note that the diffuse red signal in J is the result of the DiI signal after fixation.