Fig. 4. PAX77 cells are under-represented in the cortical proliferative layers of PAX77⁺;Tg^-wild-type;Tg⁺ chimeric embryos at E16.5. (A,B,F,G) Coronal sections through the cortex of a PAX77⁺;Tg^-wild-type;Tg⁺ chimera at E16.5. (A,B) Tg⁺ cells (marked with brown dots) and Tg^- cells were counted in the proliferative layers (VZ and SVZ), intermediate zone (IZ) and cortical plate (CP). (C-E) Ratios of observed/expected contributions of Tg^- (i.e. PAX77) cells in (C) VZ and SVZ, (D) IZ and (E) CP. (C) PAX77;Tg^- cells are significantly under-represented in the proliferative layers along the chimeric cortex and (D) in the IZ of the rostral chimeric cortex. (F,G) Example of Tg⁺ (arrow) and Tg^- (arrowhead) apical progenitors in M-phase labelled with anti-phosphorylated histone H3 (grey). Scale bars: 50 µm in A; 10 µm in B,F,G.