Summary and Perspectives
In general, axons in the adult CNS of higher vertebrates are not capable of regeneration after injury. It seems that the success of regenerative processes depends almost entirely on the environment surrounding the lesioned axon. The big challenge in regeneration research is to find the factors which render the CNS environment inhibitory to axon regeneration and to develop strategies to counteract or inactivate them. To understand the role of microenvironment, it seems highly warranted to provide comprehensive and detailed analyses of cellular and molecular lesion-induced changes. This, coupled with different approaches to rendering the environment permissive for axonal regeneration, will lead to a better understanding of the mechanisms responsible for regeneration failure and may help to devise future clinical strategies in the treatment of CNS injury and neurodegenerative diseases.