Fig. 4. Effect of tip removal on cell movement in slugs. (A) The tracks of three cells are indicated by black dots and superimposed on the brightfield image of the first time point. The arrow indicates the direction of cell movement. The pattern of dots in each track shows that cells go through phases of fast and slow movement. (B) Velocity plot of four cells, including the three cells from A. The periodic movement changes are obvious. (C) Tracks of four cells from the same slug after the tip was removed. The broken line marks the position where the tip was cut off. (D) Velocity profiles of the four cells shown in C. The coordinated behaviour of the cells is lost. Scale bar: 100 µm.
