Figure 5. DCC receptor blockade interferes with RGC axon growth cone branching in stage 40 tadpoles.

A, B) The effects of acute anti-DCC treatment on simple RGC axons of stage 40 tadpoles 24 hours after treatment on rostrocaudal growth is illustrated by the average change in axon length from its initial position at time 0 (A), and by the relative proportion of RGC axons that shortened, lengthened or remained the same length (B).C–E) The effects of DCC receptor blockade on the branching of RGC axon growth cones is shown by the quantification of the change in total branch number (C), and the change in forward (D) versus back (E), branches from the initial observation period to the next. Note that anti-DCC treatment interfered with axon branching when compared to controls (D), an effect that was significant on forward branches (D), but not on back branches (E). F) Axons exposed to anti-DCC treatment had a forward-back branch ratio that differed significantly from that of controls by 24 hours. G-J) The effects of anti-DCC treatment on branch dynamics of RGC growth cones is illustrated by the total number of branches added (G) and stabilized (H), and by the proportion of added and stable forward versus back branches (I, J) during every 2 hr observation interval and between 6 and 24 hours. Note that in contrast to control and netrin-1 treatment, anti-DCC treatment decreased both the addition and stabilization of branches. However in proportion, dynamic changes in branch addition of forward versus back branches were similar to control. *p < 0.05, **p < 0.005, and *** p < 0.0005. Error bars indicate SEM.