Figure 3

Reduced proliferative pool in mutant embryos compared to the control at embryonic day (E)13.5. (A-D) Control (A, B) or mutant embryos (C, D) were pulsed with bromodeoxyuridine (BrdU) for 12 hours to label all cells that had passed through S-phase during the pulse. (A, C) Low power images with boxed areas indicating location of higher magnification (B, D) images. (E) Quantification of the proportion of BrdU-positive cells as a proportion of total cells. The proportion of BrdU-positive cells is significantly lower in the mutant. (F, G) There are no significant differences in cell cycle (F) or S-phase (G) length between mutant and control embyos. (H, I) FACS analysis of DNA content of E13.5 control and mutant cerebral cortical cells. (H) A histogram of dissociated cells from control cerebral cortex indicating populations in G0/G1, S, and M-phases of the cell cycle sorted by their DNA content. (I) The proportion of cells in each phase of the cell cycle, calculated from histograms like those shown in (H), in control and mutant cerebral cortex. The mutant has significantly more cells in G0/G1 and significantly fewer cells in S/G2 than the mutant, consistent with a reduction in the population of proliferating cells. All sections are coronal and dorsal is up. Scale bars: (A, C) 400 μm; (B, D) 50 μm. Error bars in (E, F, G, I) are standard error of the mean with Student's t-test p-values for control versus mutant comparison indicated above bars.