Fig. 8. EYFP⁺/ß-gal⁺ neurons of layers II and III are born after Cre transfection. P5 cortices after double electroporation of pCAG-EYFP (A-D) or pCAG-ExNotchZ at E13.5 (E-H), and of pXCANCre at E15.5, and after BrdU labeling at E16.5, are shown. Red and green signals show immunostaining with the anti-BrdU and anti-GFP antibodies, respectively. Arrowheads indicate neurons that were heavily labeled with BrdU. C and G are merged views of the sections shown in A and B, and E and F, respectively. (D,H) Ratios of neurons that were heavily (h) and lightly (l) labeled with BrdU in the EYFP⁺ population. Ratios were calculated from 5 brains. After EYFP transfection, layers II and III contained 46.1±3.7% heavily- and 12.0±3.4% lightly-labeled neurons, whereas layer IV contained 2.9±0.1% heavily- and 1.3±1.1% lightly-labeled neurons. EYFP/caNotch transfection showed 48.1±3.5% heavily- and 8.2±2.3% lightly-labeled neurons in layers II and III. Scale bars: 200 µm for A,E; 20 µm for B,C,F,G.