Figure 9.

Relationship between the turning angle and the angle of incidence of the gradient. (a) Bar chart showing the mean total turning angle of a growth cone exposed to different angles of orientation (45° sectors) of the netrin-1 gradient (solid bars) compared to the no netrin-1 control group (striped bars). The mean turning angle in axons oriented 35°–55° to the netrin-1 gradient is indicated (blue dashed line) on the plot. The axons exposed to the gradient at an angle 0°–45° (black, n=71) were significantly different from those at an angle 90°–135° (light gray, n=83) (P-value<0.01, using the Kruskal–Wallis test). (b) Cumulative distribution plot of the total turn (angle) of growth cones exposed to different angles of orientation (45° sectors) of the netrin-1 gradient. (c) Bar chart showing the average total turning angle of a growth cone exposed to different angles of orientation (45° sectors) of the netrin-1 gradient and different concentration regions (0–50, 50–100, 100–150, 150–200 ng mL⁻¹). Error bars denote s.e.m. (n=5–29). The asterisks denote the statistical significance (P-value<0.01, using the Kruskal–Wallis test). Negative values indicate a turn in the direction of the gradient.