Figure 5.

Mobile vesicles release their contents. (A) Normalized time course of peptide release from growth cones with mostly mobile vesicles labeled with the inducible construct. Data derived from epifluorescence measurements from four growth cones. Note that residual fluorescence present after depolarization because of cell autofluorescence, light scattering, and unreleased peptide is not shown in this graph. Sustained depolarization began at 0 min. (B–F) Color-coded feature-extracted images of vesicles in a stimulated growth cone. Two images were acquired 5 s apart and then color coded as described in the text. Mobile vesicles appear red or green and stationary vesicles are yellow. The yellow vesicle in B subsequently moved, indicating that it was a mobile vesicle that had paused randomly. Note that sustained depolarization causes red and green vesicle images to disappear, indicating that mobile vesicles undergo exocytosis. Similar results were obtained in three other experiments.