Figure 3: Elongation and rupture of MKs.

(a) Time lapse observation of a single MK (). The origin of time is defined as the moment when the circulating MK is captured by a pillar. The first rupture occurs at t = 27 min, when a portion of string bearing 6 beads detaches from the rest of the cell. Other similar events occur at later times, involving one (t = 29 or 31 min) or several (t = 46 min) beads. Scale bar, 20 m. (b) Length of a megakaryocyte (n = 1). Stars (*) indicate fragmentation and numbers indicate different phases of the elongation process: (1) reorganization of proplatelets, (2) anchoring to a 2nd pillar, (3) dissociation from 1st pillar, (4) reorganization of proplatelets, (5) untangling of megakaryocyte segments (6) retraction of the residual chain. The time t = 0 min corresponds to the megakaryocyte anchorage to the first pillar. The sequence of pictures presented in panel (a) corresponds to snapshots taken between times depicted by arrows 3 and 5. The data are extracted from video 3.