Figure 4

Reduction in the number of cortical progenitor cells in the developing Dicer null cortex. (A-D) The total cortical width and ventricular zone width were measured at three points across each section (medial, lateral and midpoint) and averaged. A total of three matched sections from two or three (E13.5 and E15.5, respectively) Dicer null and control littermate embryos were analysed. There was a significant reduction in both the total cortical width (P = 0.0006) and the ventricular zone (P = 0.003) by at E15.5 but not at E13.5. (E, F) There was a significant reduction (P = 0.02 and 0.001, respectively) in the number of basal progenitor cells (Tbr2+) and proliferating cells (Ki67+) in the E15.5 Dicer null cortex. (G-H) Cells expressing aCasp3 were far more prevalent in the Dicer null cortex at E15.5 compared to controls (P <0.01). A larger proportion of aCasp3+ cells were located in the VZ in Dicer null cortex than the wild-type (72.0% and 33.5%, respectively; P = 0.02). Counts were performed on three sections from two wild-type and two Dicer null cortices. Scale bars: 50 μm.