Effect of cytochalasin D on morphology of GC cultured on LN substratum. GC from small and large follicles were cultured for 48 h on LN with or without (control) cytochalasin D at different concentrations (between 0.05 and 5 μg/ml) in culture medium, and then actin was stained with FITC-conjugated phalloidin. (a): representative microscopical fields of cultured GC; GC spread on LN in control or in presence of low concentrations of cytochalasin D; most cells adopted a spindle-shaped morphology at 0.5 μg/ml of cychochalasin D, then rounded up at higher doses. (b) and (c): percentages of unspread cells, i.e. spindle-shaped (dashed line) and round (solid line) GC from small (b) and large (c) follicles; empty bars: percentages of round cells in control; solid bars: percentages of round cells with anti-α6 IgG (0.5 μg/ml) in culture medium. Data represent mean ± SEM of 3 independent experiments. In each graph, different letters indicate significant differences (p < 0.001); *** : p < 0.001, with vs. without anti-α6 IgG.