Fig. 3

Epithelial wound healing by lamellipodia-dependent cell migration has three distinct phases. a Lamellipodia are clearly evident in Phase 1 (arrowheads). (Note that in the upper left portion of the wound there is a tear in the basement membrane (*) which heals by a different mechanism – see text). b In Phase 2, lamellipodia begin to meet across the wound gap. The region of contact is extending by “zippering” (arrows). c Puckers in the area that “zippered” indicate that contraction has begun (arrow indicate zippers, outlined arrows indicate contractions). d Contractions continue along the length of the closed wound (outlined arrows). e Reduced “puckering” indicates the progressive relaxation of contractions. Areas that contracted first also relaxed first. f At 55 min, the epithelial sheet is intact and no scarring is apparent. g-l Tracing of the perimeters of the cells shown in a-f. Wound marginal cells change shape (e.g. cell 2, highlighted in red) and position (e.g. cells 8–11) dramatically during wound healing. Much of the shape change is associated with contraction of the edge of the cell at the wound periphery. The shape change persists even after the wound is healed. Interestingly, cells that were not directly in contact with the wound (e.g. cell highlighted in green) show little if any shape change. m-n Actin accumulates at the site of a recently closed epithelial wound. m DIC of fixed cells after closure of a linear wound. The seam is a region where lamellipodia have zippered together. n Phalloidin staining of the cells in (n) shows accumulation of actin at the seam. Experiment was replicated >10 times. Scale bar = 50 μm