Fig. 5.

Neurite length versus time for individual pontine (A–C, E) and olivary growth cones (D) after the addition of collapsin-1 (50 ng/ml). Each trace represents the extension of a single growth cone. Each graph represents growth cones observed in a separate culture. A, Pontine neurite extension is initially steady, but neurites rapidly retract after collapsin-1 addition (arrow); ∼40% of pontine growth cones exhibit this response to collapsin-1. B, Pontine neurite extends and then rapidly arrests after collapsin-1 addition; ∼20% of pontine growth cones exhibit this type of response to collapsin-1.C, Pontine growth cone does not alter its advance after collapsin-1 addition; ∼40% of pontine growth cones continue to advance in collapsin-1. D, Examples of the ∼80% of growth cones from inferior olivary explants that do not alter their extension rates after the application of collapsin-1. E, Long-term observation of a pontine growth cone. Approximately 2 hr after collapsin-1-induced neurite retraction the growth cone recovered and advanced at a rate comparable to that before collapsin addition (arrow).