Mechanisms of growth cone guidance and motility in the developing grasshopper embryo

During neuronal pathfinding in vivo, growth cones must reorient their direc tion of migration in response to extracellular guidance cues. The developin g grasshopper limb bud has proved to be a model system in which to examine mechanisms of growth cone guidance and motility in vivo. In this review we examine the contributions of adhesion and multiple guidance cues (semaphori ns 1 and 2) in directing a growth cone steering event. Recent observations have suggested that the tibial pioneer growth cones are not directed via me chanisms of differential adhesivity. We present a model of growth cone stee ring that suggests a combination of adhesive and guidance receptors are imp ortant for a correct steering event and that guidance molecules may be impo rtant regulators of adhesive interactions with the actin cytoskeleton. (C) 2000 John Wiley & Sons, Inc.