Fig. 9. caNotch⁺ progenitors lose the ability to generate low-layer neurons. Shown are P5 cortices after transplantation at E13.5 of progenitors that had been prepared after electroporation of pCAG-ExZ at E13.5 (A,E), after double electroporation of pCAG-ExZ at E13.5 and pXCANCre at E15.5 (B,F), or after double electroporation of pCAG-ExNotchZ at E13.5 and pXCANCre at E15.5 (C,D,G). Blue and red signals show immunostaining with antibodies recognizing ß-gal (A-D) and Lhx2 (D), respectively. C and D show the same section. D is a merged view. All ß-gal⁺ neurons were also positive for Lhx2. E15.5 progenitors single transfected with pCAG-ExZ at E13.5 showed the same results as did E15.5 progenitors double transfected with pCAG-ExZ at E13.5 and pXCANCre at E15.5 (data not shown), confirming that Cre did not affect the laminar fate of neurons. (E-G) Ratios of ß-gal⁺ neurons that were distributed to each layer of the cortex. Each ratio was calculated from 10 brains. Results were as follows. In E: layers II and III, 23.8±9.1%; layer IV, 32.7±5.1%; layer V, 40.1±8.7%; layer VI, 0.3±0.5%; and white matter (WM), 3.1±2.3%. In F: layers II and III, 97.1±3.5%; layer IV, 1.0±1.2%; layer V, 0.9±0.7%; and WM, 1.1±3.1%. In G: layers II and III, 89.7±7.4%; Layer IV, 4.3±3.5%; layer V, 2.0±4.2%; layer V1, 1.8±0.5%; and WM, 0.3±1.1%. Scale bar: 150 µm for A-D.