Question

Under certain circumstances, axons in the peripheral nervous system can regenerate after sustaining damage. Why is axonal regeneration in the central nervous system much less likely?

Answer 1

There are two reasons that the environment around the CNS axon leisoins are inhibitory to axon growth and they have a feable regeneration response after a damage. We have three major glial cells which are oligodendrocyte,astrocyte,microglia. Among them some of their precursors stand as an extrinct barrier to the regrowth in injured CNS. After CNS injury glial scar occurs and there is the presence of chondroitin sulfate peoteoglycan in it which is the major inhibitory hormone. The glycosaminoglycan sugar chain is to be digested by the chondroitinase ezyme which can remove the inhibitory action then. This is not possible in the CNS like PNS and the axonal regeneration is CNS is much likely less.