Mitochondrial transport during axonal elongation. Chicken DRG neurons were grown on coverslips coated with laminin/poly-L-ornithine for 2 d and stained with 0.1 µM MitoTracker red CMXRos. Images were acquired every 2 s, but to reduce the size of the movie, one frame for every 4 s is shown. In the movie, the growth cone is toward the right-hand side. During the process of growth cone advance, mitochondria docked along the axon move at a low velocity in the anterograde direction in a coherent manner. During periods of rapid growth cone advance, mitochondria in the growth cone are left behind in regions of newly consolidated axon (between the 30- and 45-min time points). During periods of growth cone pauses, the low velocity anterograde transport of docked mitochondria continues (between the 52- and 62-min time periods). Over the course of the movie, increases in the distance between pairs of docked mitochondria can be observed. This movie illustrates low velocity transport during axonal elongation and a brief pause. Bar, 10 µm. Images were acquired on a confocal system (FV300 FluoView; Olympus) on an IX70 microsocpe using a 60×, 1.4 NA, PlanApo objective. Samples were illuminated with an argon/krypton Omnichrome 488/568/647 line laser set to standby mode, with the laser intensity set at 6%, the confocal aperture set at 5, and pixel dwell times of either 100 or 200 microsec; the light was further attenuated with neutral density filters (either 25 or 50%). Cells were observed in an enclosed flow chamber. Temperature was maintained at 37°C. This movie corresponds to video 2 from J Cell Biol. 2006 May 8;173(3):373-81.