Final answer:
Axonal regeneration in the CNS is impeded due to myelin debris, inhibitory molecules, and glial scarring, unlike in the PNS where Schwann cells support regeneration.
Step-by-step explanation:
Axonal regeneration does NOT occur in the CNS due to the persistence of myelin debris, secretion of neuronal inhibitory factors, and dense glial scarring. Unlike the peripheral nervous system (PNS), the CNS lacks Schwann cells, which aid in the regeneration of axons by creating a myelin sheath around the neuron axons. Moreover, in the CNS, the oligodendrocytes, which myelinate axons in the CNS, do not support regeneration and, along with other factors like the secretion of inhibitory molecules and physical barriers from glial scars, inhibit axonal growth.