ABSTRACT
The function of the nervous system consists primarily of transmitting signals rapidly and accurately between its different components. To do so it crucially depends on their correct wiring. But how are these connections established during the development of the nervous system? How do neurons find their way to distant targets to form specific connections during synaptogenesis? Although we have detailed descriptions of the connectivity of individual parts of the brain or the spinal cord we still know little about the mechanisms by which neurons become appropriately interconnected or how they reach their non-neuronal targets during development. However, several model systems have been developed in which pathfinding decisions of neurites can be studied. The same basic rules seem to be followed in invertebrates and vertebrates. Therefore, it has been possible to combine knowledge based on the analysis of genetic mutants of invertebrates with results from functional analyses of higher vertebrates. In addition to the general mechanisms the families of molecules involved in pathfinding are also conserved. Therefore, the mutual exchange of knowledge gained by studies in different species has been and will continue to be helpful in the elucidation of the complex processes of growth cone guidance and pathfinding.
