Fig. 6

Visualization of filopodial protrusions on the axon shafts by ASEM. a An ASEM image of an E16 cortical axon under basal conditions (a negative control). (b–e) ASEM images of E16 axons treated with netrin-1 for 10 min (b), 30 min (c, d) and 4 h (e), showing netrin-1-induced filopodial protrusions. The image presented in c and the images presented in Fig. 5 are of the same neuron. f An ASEM image of an E16 axon treated with netrin-1 for 30 min in the presence of an anti-DCC function-blocking antibody. Few protrusions were found on the axon shaft. g ASEM images of E14 cortical culture under basal conditions, showing protrusions on the shaft of an axon. The rectangle with broken lines in (g2) indicates the area shown in g1. h A set of ASEM images of an E14 axon treated with netrin-1 for 30 min. Original magnifications are 6000× (a–f, g1, h) and 2000× (g2)