Fig. 6.

Activity can reorganize and stabilize F-actin. In 17-d-old neurons, 5 min exposure to 75 mm KCl results in an increase in phalloidin-labeled F-actin in the cortex and dendritic protrusions [control (A, con) vs stimulated (B)], and intensity of synaptophysin (syn)-labeled puncta appears to increase and spread slightly in the same neurons [control (E) vs stimulated (F)]. When neurons incubated in latrunculin A (lat) for 24 hr (C,G) are compared with those that were first stimulated for 5 min with 75 mm KCl (D,H), there are more phalloidin-labeled F-actin puncta (D vs C) that codistribute with synaptophysin-labeled puncta (G,H) (compare C and Gwith D and H). Scale bar, 20.2 μm.