Fig. 3. Mitral cells are derived from the rostral part of the wild-type telencephalon. (A) Experimental procedures for cell tracing of the mitral cell progenitors by electroporation of GFP-expression vector. (B-D) A rostral-lateral view (B) and parasagittal sections (C,D) of the head of electroporated, wild-type embryos. At 24 hours after electroporation, strong GFP-fluorescence is seen at the rostral area of the telencephalon that expresses Pax6 (C,D). (E-E'',F-F'') Distribution of GFP-positive cells in the telencephalon after 2 days of TOC. The OB evaginates at the rostral-most area of the telencephalic explants. F-F'' are transverse sections of a TOC sample. GFP-positive cells contribute to the OB marked by CR and Nrp staining (E',F'). (G-G'') Confocal images of GFP-positive cells in the OB. Nrp is expressed at the neuropiles of the GFP-labeled cells (arrowheads). (H-H'') BrdU incorporation in the GFP-positive cells in the OB. tel, telencephalon; LV, lateral ventricle. Scale bars: B-D, 500 µm; E-F'', 100 µm; G-G'', 20 µm; H-H'', 10 µm.