Fig. 7. Exocytosis contributes a patch of unlabeled surface to the new plasma membrane domain of an FM1-43-labeled embryo. Three representative sequences, A1-4, B1-4 and C1-4, taken from time-lapse Movie 2 (see http://jcs.biologists.org/supplemental), display a particularly active site recorded near the arrow in Fig. 6. Expanding dark regions (arrows) indicate sites of displacement of FM1-43-labeled membrane. Frames were recorded at 1.8 second intervals. Bar, 10 µm.