Fig. 1. Growth cone advance and veil dynamics. (A) Growth cone advance. Blue line traces path traveled by growth cone during a 3-hour time-lapse observation. ^* indicates start point. (B) Veil dynamics. Kymographs (right) of veils in growth cone front (top, left) and rear (bottom, left) show alternation of protrusion and retraction. Black line denotes path along which kymograph was obtained. (C) Orientation of protrusion and retraction phases. `Other' denotes veil dynamics – collapse, ruffling or stalling – not readily categorized as protrusion or retraction. n=151 veils; 20 individual growth cones; 352 minutes observation; 329 transitions recorded.