Fig. 6. Analysis of MT shortening. (A) Time-lapse sequence shows a rare event of plus end shortening (arrowheads) from the plasma membrane back to the centrosome within 12 seconds. (B) Histogram of instantaneous rates of MT shortening from the plasma membrane. (C) Length distribution of MT shortening episodes. MT ends adjacent to the cell margin were followed and the length of a continuous shortening episode was determined. The histogram shows small shortening episodes were frequent and long ones rare (n=319). (D) Time-lapse sequence shows release of a MT from the centrosome followed by shortening from the minus end (arrowheads). Time in seconds; bars, 5 µm.