Quantification of VD/DD growth cone dynamics. (A) A time lapse series of a wild-type VD growth cone showing the emergence and retraction of an individual filopodium (arrows). The scale bar represents 5 μm, and the time after the start of the time lapse experiment is indicated in the lower left of each panel. (B-D) Quantification of filopodia initiation rate, stability, and maximal length. Error bars represent standard error of the mean. Asterisks indicate significant differences between wild type and the mutant (P < 0.0006). NS = not significantly different. The number of growth cones analyzed and the total number of filopodia (in parentheses) is indicated in the bars in (D). (B) Initiation rates of filopodia (average initiation events per minute); (C) average filopodial duration (in minutes); and (D) average filopodial maximal length.