Regeneration in the adult mammalian CNS: guided by development.

In the past year, the roles and mechanisms of molecules involved in cell survival (glial-derived neurotrophic growth factor), growth cone guidance (netrins and semaphorins), axonal outgrowth and sorting (neural cadherin, polysialylated neural cell adhesion molecules, and L1), and neuronal connectivity (cell adhesion molecules, dystroglycan, and agrin) have been described during development and, to a limited extent, in the mature CNS. Evidence is now emerging that some developmental events, such as the expression of polysialylated neural cell adhesion molecule and L1, are recapitulated during adult CNS regeneration. These results suggest new avenues to address more accurately the challenges of axonal regrowth in the adult mammalian CNS.