Cyclic remodelling of growth cone lamellae and the effect of target tissue.

We report the existence of cyclical fluctuations in the total size of growth cone lamellae, represented by membrane protrusions and retractions, and show that aspects of this behavior can be regulated by the target tissue for the nerve fibers. The transition of the growth cone from a high to a less motile state, which occurs in the presence of the target tissue, has implications for the mechanisms that underlie nerve fiber elongation during development.