Neural development: Axon regeneration derailed by dendrites

摘要

Maturing neurons gradually lose the ability to regenerate axons. In the retina, signals from neighboring cells have been found to induce a perinatal switch from extension of axons to extension of dendrites, a change that may contribute to regeneration failure. As the central nervous system (CNS) matures in postnatal life, there is a decline in the ability of neurons to regenerate axons following injury. Embryonic CNS neurons in m.any vertebrate animals will readily regenerate following even the most severe traumas. For example, full functional recovery is made after a complete spinal transection in embryonic chicks [1], so long as the transection occurs before the midpoint of embryonic development. Following this point, there is a rapid decline in the ability of CNS neurons to regenerate axons after injury, culminating in complete regenerative failure by early postnatal stages.