Figure 7.

Local application of netrin-1 increases outgrowth in stimulated processes and retraction in unstimulated processes. A, DIC images before (top left) and after (top right) local application of netrin-1 to the axon shaft. Filopodia (red and green arrowheads) showed increased calcium activity (bottom panels) and rapid branching during the experiment whereas the primary axon (black arrowhead) showed little calcium activity and retracted. Examples of fluorescence before application of netrin-1 (time point −5:00) and of fluorescence during localized calcium transients evoked by netrin-1 (times 10:30 and 18:20) are shown below. Pseudocolor scale bars indicating fluorescence intensity or normalized fluorescence intensity are shown to the side of the respective images. B, Graph of calcium activity in processes from A indicated by the colored arrowheads. Scale bar, 10 μm.