Figure 2.

Typical time-lapse movie and image analysis of neutrophil engulfing an IgG-coated bead. Here the bead has diameter 4.6 μm. Data from Herant et al. (14). (A) Raw images of three frames at various stages of engulfment. At t≈2 s, the bead has been released onto the cell, with a contact area of a≈2 μm. At this point engulfment has not yet started. At t≈27 s, the bead is approximately half-engulfed, with the lower lobe noticeably ahead of the upper lobe. At t≈48 s, engulfment is complete, the bead is entirely within the cell, and the phagosome is fully formed. Scale bar: 5 μm. (B) The same frames as in panel A after automatic image analysis. (Blue) Cell; (red) bead; (green) outline of the pipette; (yellow) membrane attached to the bead. (C) Engulfment as a function of time. For both the upper and lower lobes, after engulfment begins at t≈10 s, there is an initial slow stage (light gray) followed by a much quicker second stage (dark gray). Engulfment is complete by t≈46 s. To see this figure in color, go online.