FIG. 7.

E2F3 positively regulates progenitor proliferation. Sections from E15.5 E2F3-deficient embryos and their corresponding wild-type littermates were labeled with an antibody to PH3 to label cells in the M phase of the cell cycle (A). PH3-labeled cells lining one lateral ventricle were counted every fifth section between anatomical landmarks, and the total number of PH3-labeled cells counted was expressed as the mean ± SEM. (B). Significantly fewer PH3-labeled cells were observed for E2F3^−/− embryos than for wild-type littermates (B) (four embryos per genotype). Cell death was assessed by examining both TUNEL and AC-3 immunohistochemistry combined with Hoechst nuclear staining at E13.5 (C). Labeled cells were quantified throughout the telencephalic hemisphere from eight matched sections per embryo. No difference in the levels of cell death between control and E2F3-deficient embryos was detected (C) (three embryos per genotype). Significance was determined using a two-tailed t test. *, P < 0.05. Bar = 250 μm. ge, ganglionic eminence.