Fig. 3. Comparison of AF and MT organization in chick DRG growth cones at a CSPG border in the presence and absence of 4 nm vinblastine and 7 nm taxol. A, D, G, Phalloidin-labeled AFs. B, E, H, Tyrosinated α-tubulin labeling. C, F, I, Detyrosinated α-tubulin labeling. A–C, A control growth cone turning to avoid growing on CSPG. D–F, A growth cone exposed to 4 nm vinblastine that has contacted the CSPG border.G–I, A growth cone treated with 7 nm taxol that is stopped at the border. The CSPG border is shown in A, D, and G. In G, the border was digitally enhanced to make it more visible. Vinblastine- and taxol-treated growth cones do not turn to avoid CSPG, but instead stop, retract, or sidestep laterally along the border. Arrowsin E and H show that, in drug-treated growth cones at CSPG borders, the organization of Tyr-MTs is similar to that of drug-treated growth cones migrating on FN (see Fig. 2). Scale bar, 10 μm.