Waypoint Navigation in the Embryo

Waypoint navigation is the guidance of cells from origin to destination by way of a chain of intermediate targets. Once a cell reaches a particular intermediate target it loses interest in it and begins to move to the next target in the chain. There is evidence for this in insects, in particular, for migration of primordial germ cells and some neuronal growth cones. Growth cone navigation in vertebrates uses similar systems, though the waypoints tend to be larger than individual cells. Waypoint navigation is also seen in regeneration: growth cone navigation during head regeneration in planaria is presented as an example.