Individual filopodia rotate in the direction of a right-handed screw. (A) Time-lapse DIC images of filopodia of a single growth cone in a 3D collagen gel. (inset) Cartoon showing the experimental setup of a growth cone migrating in the gel (dark pink) toward the objective lens (gray). The focal plane was positioned at the level of the filopodial tips. Representative trajectories of the filopodial tips are indicated by series of color-coded diamonds. Each color corresponds to the single filopodium tracked for a maximum of 100 s. Each diamond represents the position of the tip at 1-s intervals. (B) The line traces indicate the paths of the single filopodial tips shown in A. Arrows indicate the direction of movement, showing that the filopodia display a general tendency to rotate counterclockwise from the observer’s perspective. (C) Time-lapse DIC images and representative trajectories of filopodia of a growth cone that has protruded from a collagen gel (dark pink) into a liquid medium (light pink). Each color corresponds to the single filopodium tracked for a maximum of 100 s. Each diamond represents the position of the tip at 1-s intervals. (D) The line traces indicate the paths of the single filopodial tips shown in C. Arrows indicate the direction of movement. (E) Schematic diagram of a growth cone showing individual filopodia rotating in the right-screw direction on their longitudinal axis. Original image data of A and C can be found in DataViewer. Bar, 5 µm.