Chapter 30 Regeneration of axons from the central nervous system of adult rats

Abstract

Publisher Summary This chapter discusses the studies of the origin and course of the central nervous system (CNS) axons that regenerate along peripheral nerve grafts and summarizes preliminary observations on the terminations of such axons when they are directed to reenter the CNS. In contrast to the well-documented failure of interrupted axons to regenerate within the CNS of adult mammals, many neuronal populations in the brain and spinal cord of adult rats can regrow axons after injury, if the growing axonal tips are exposed to the milieu provided by the nonneuronal environment of peripheral nerve grafts. This regenerative capacity, suspected by earlier investigators by using light microscopy, has now been established by the use of retrograde labeling methods that permit the identification of the CNS neurons whose axons have grown into the peripheral nerve grafts. Neurons in most regions of the CNS are able to elongate their axons into peripheral nerve grafts. However, there are examples of unequal responses among different populations of neurons in the same region.