Factors intrinsic to the neuron can induce and maintain its ability to promote axonal outgrowth: a role for BCL2?

The adult CNS provides a poor environment for axonal growth and regeneration. The question of to what extent the loss of axonal growth occurring as the brain matures is dependent on factors intrinsic or extrinsic to the growing neuron is still unanswered. Examination of axonal growth from neural transplants provides insight into the roles of growth factors, inhibitory molecules, growth-promoting substrates and the differences between CNS and PNS environments in the regulation of neurite extension. The data that imply a role for BCL2 and related molecules in such processes are reviewed in this article, which analyzes the factors intrinsic to the neuron that control its capacity for axonal growth.