Myosin II inhibition attenuates veil retraction but does not affect reductions in actin veil network densities evoked by Arp2/3 complex inhibition. (A) Electron micrographs of growth cones treated with blebbistatin (60 µM, 20 min, top) or pretreated with blebbistatin (60 µM, 10 min) followed by blebbistatin and CK666 (50 µM, 20 min, bottom). Blue boxed areas on the left panels are presented in high magnification on the right. Asterisk, actin veil; arrows, edge of veils. (B) Quantification of actin veil network properties from 1 × 1 µm² regions in distal P-domain of growth cones treated as in A. Data for control and CK666-treated growth cones from Fig. 2 G are shown for comparison. n, 45 regions from 3 GCs for blebbistatin; 42 regions from 3 GCs for blebbistatin with CK666. *, P < 0.01 with two-tailed unpaired t test versus control; NS, not significant. (C) Representative images of the leading edge of growth cones treated as in A. See Fig. S5 A for the entire growth cones. (D) Histograms of exposed filopodium lengths. CK666 and control from Fig. 2 E for comparison. See Fig. S5, B and C, for statistical analysis. Bars: (A, both panels) 2 µm; (C) 5 µm.