The effects of NT-3 beads over a three-day culture period. (A) After 24 days most cases did not show any axonal response to the NT-3 bead as in NGF cases. (B) In a couple cases axonal responses to the NT-3 bead became apparent by 24 h. Axonal effects were pronounced by the end of the second day (C, D) and not much different from that seen by the end of the third day (E, F). Many axons within the tract formed interstitial branches that extended towards the bead and arborized extensively (arrows D, F) or formed “knots” (arrows, C, E). Dashed circles outline the beads and asterisks mark the center of the beads. Scale bar=150 μm.