Fig. 2. Ngn2-expressing progenitors give rise to post-mitotic dentate granule neurons. (A-C) Sections through the hippocampus of Ngn2^KIGFP/+ embryos at E18.5 (A), P1 (B) and P5 (C) immunolabelled for GFP. (D-G') Hippocampal sections of P1 Ngn2^KIGFP/+ brains showing the secondary matrix immunostained for GFP and BrdU after a 30 minutes pulse (D,D'), Prox1 (E,E'), HuC/D (F,F') and Neurod1 (G,G'). Arrows indicate double-labelled cells. (D'',E'',F'',G'') Histograms representing (D'') the percentage of GFP-expressing cells that have incorporated BrdU (blue bars) and the percentage of BrdU-labelled cells expressing GFP (red bars), (E'') the percentage of GFP⁺ cells expressing Prox1 at a low level (light blue bars) or at a high level (blue bars) and (F'',G'') the percentage of GFP⁺ cells expressing HuC/D (F'') and Neurod1 (G''). The high level of GFP expression in Ngn2^KIGFP/+ mice (A) compared with Ngn2 expression (Fig. 1B) reflects the greater stability of GFP. Almost all post-mitotic dentate granule neurons are GFP⁺ and therefore originate from Ngn2-expressing progenitors. Differences in GFP labelling in E-E' and other panels are due to the lower signal obtained with chicken anti-GFP antibody. Scale bars: 100 µm in A-C; 20 µm in D-G. 1ry, primary matrix; 2ry, secondary matrix; 3ry, tertiary matrix; DG, dentate gyrus.