SEM of C2C12 myotubes treated with WF (5, 10, 15, 20, 25 μg.mL-1 for 24 h). A, in the absence of WF, C2C12 myotubes had a normal, elongated shape. B-H, C2C12 myotubes incubated for 24 h with 1 (B), 3 (C), 5 (D), 10 (E), 15 (F), 20 (G) and 25 (H) μg of WF.mL-1. The morphological analysis of WF-treated C2C12 cells revealed a loss of cell-to-cell contact, with consequent detachment and damage to the collagen matrix (arrowheads), cell retraction, altered cell shape and vesicle formation (arrows in panel E, F and H). 2500×.