Fig. 3. Filopod formation, retraction and relocation for a representative cell turning towards an aggregation stream in response to a spatial gradient of chemoattractant. (A) Reconstruction of the full cell, including nucleus, pseudopodia and filopodia. (B) Reconstruction only of pseudopodia and filopodia. The cell is viewed from 55°. Time is presented in seconds (sec). The arrow in the lower right corner of the 0 second panel denotes the direction of the aggregation stream, which is out of sight beyond the lower right-hand corner. See legend to Fig. 1B for color code. A, anterior end of cell; U, uropod; a, b, c, pseudopodia in order of appearance.