Tracing the spatiotemporal dynamics of BBs. (A) Migratory tracks of individual BBs recruited into eight alignments indicated by different colors. See Video 3. Time stamps shown are in hours:minutes. (B) Time course of BB alignment evaluated using Ia. A, alignment; P, partial alignment; S, scatter; F, floret. Horizontal dashed lines indicate boundaries that separate different patterns. (C) Number of BBs in individual cells during the development of BB alignment. The number of BBs remained almost constant during the stereotyped patterns of BB development. Note that apparent small fluctuations in BB numbers were caused by the fact that part of a cell was occasionally out of focus during the live imaging. (D) Temporal change in the velocities of BBs averaged within single cells (left). BB motion drifting caused by cell stretching (right, blue box) and BB motion under no significant cell deformation (right, pink box). Quantitative analyses in B–D were performed using the same cells (n = 14). Gray regions in B and D represent the 25–75 percentile band at each time point. Bars: (A) 5 µm; (D) 10 µm.