Figure 4
Experimental observations of the “pull” and “protrusion-related push” behavior of the tip cell (in green circle).
These two in-focus images were generated with the two stacks of bright-field images (with a z-step size of 0.75 μm) that were sequentially acquired with a time interval of 15 minutes. The beads that had the observable movement pattern associated with the “pull” type behavior were highlighted with orange circles in both images whose centers were coincident with the locations of those beads in image A-I. They were pulled toward the neighboring protruding lamellipodium, as manifested in image A-II by the deviatioin of their positions from the centers of the circles containing them. It should be noted that the highlighted beads were not in the same plane (which was observed prior to focus stacking). The beads (shown by arrows) linked to the “protrusion-related push” type behavior had a trajectory along the major axis of their relevant ellipse, almost consistent with the protruding direction of the associated lamellipodia.
