Fig. 4. Spine abnormalities induced by ARHGEF6 knockdown in hippocampal organotypic slice cultures. (A) Dendritic segments in cells transfected with EGFP (Ctrl) or co-transfected with EGFP and either a non-silencing siRNA or silencing siR1 and siR2 constructs. Note the increase in elongated spines and filopodia. Bar, 3 µm. (B) Blind quantitative analysis of large mushroom-type spines (spine head diameter >0.7 µm) shows a significant reduction in siR1 (dark grey bar) and siR2 (grey bar) transfected cells versus EGFP-transfected control neurons (white bar) or non-silencing siRNA transfected cells. (C) Increase in filopodia observed under the same experimental conditions. (D) Increase in elongated spines (1.8 µm). Data are mean ± s.e.m., n=6-20; ^*P<0.05.