Fig. 6. MALS^TKO embryos display significant differences in labeling index and quit fraction during early neurogenesis. (A-H) Coronal sections of E11.5 (A,B), E12.5 (D,E) and E13.5 (G,H) MALS^TKO mutants and matching littermate control brains injected with BrdU 2 hours (A,B,G,H) or 24 hours (D,E) before sacrifice. Sections were immunostained with antibodies to BrdU (A,B,D,E,G,H) and Ki67 (D,E). (C) At E11.5, MALS^TKO progenitors have a lower labeling index (total number of BrdU⁺ cells/total number of cells) than do controls. (F) A larger number of MALS^TKO mutant progenitors at E12.5 have quit the cell cycle relative to control littermates (BrdU⁺ Ki67^-/total number of BrdU⁺ cells). (I) MALS^TKO mutant progenitor cells recover normal cell-cycle dynamics just a day later at E13.5, at which time no differences in the labeling index are apparent. Scale bar: 10 µm.