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Abstract

Axons mechanically or chemically deflected from their normal route can sense directional cues within the target organ and can correct their routes correspondingly towards the specific target area. During the search for guiding cues it has been shown in vitro that certain properties of cell membranes depend on the position of the cells from which the membranes are derived. Using living growth cones as tools to investigate cell surfaces it has been established that there are several differences between membranes of anterior and of posterior tectal cells and that, furthermore, nasal and temporal axons themselves carry different recognition markers. Possible connections between position-dependent membrane properties, directional cues for growing axons, and map formation will be discussed.