Figure 3.

Leader cells and single-cell speed are insufficient to explain wound dynamics. (a) Characteristic leader cell observed in our experiments, identified by the perimeter of the lamellipodium (red line) being two- to threefold larger than a typical cell on the boundary (12, 58). Scale bar, 20 μm. (b) The border velocity does not depend significantly on leader cell number for I-FN (red), I-PL (green), or II-FN, but does increase for MDCK II cells on PL (Fig. S1f). Box-and-whisker plots indicate the median, extrema, quartiles, and outliers for the indicated number of leader cells (n). (c) Cell perimeters are measured manually in ImageJ (59) (yellow contours) and used to compute the ratio of perimeter to the square root of cell area, p₀. The values of this parameter for the cells shown are 4.26 (I-FN) and 4.17 (I-PL). (d) Histogram of the persistence times computed by fitting mean-squared displacements from isolated cell movements for I-FN (red) and I-PL (green) to a persistent random walk model. Inset shows the corresponding average values for the persistence times. To see this figure in color, go online.