Cns nerve fibers regenerate because of the actions of schwann cells.. what does the schwann cells do?

Explanation:

Schwann cells, also called neurilemma cells, are any of the cells in the Peripheral Nervous System (PNS) that produces the myelin sheath around neuronal axons. Schwann cells are equivalent to a type of neuroglia called Oligodendrocytes found in the Central Nervous System (CNS). Schwann cells are named after German Physiologist, Theodor Schwann.

Schwann cells are known for their roles in supporting nerve regeneration. Nerves in the PNS consists of many axons myelinated by Schwann cells. After nerve injury, Schwann cells aid in digestion of its axons (phagocytosis). The Schwann cells distal to the damaged area lose contact with axons as they degenerate. This represents a radical change in the signaling environment, because key signals for the control Schwann cell phenotype come from axons. Subsequently, further change is provided by a cocktail of bioactive factors secreted by macrophages, which invade injured nerves in large numbers. In response to these perturbations, Schwann cells show a remarkable response. This is the conversion of Remak and myelin cells, within their original basal lamina tubes, to a Schwann cell phenotype, the repair Schwann cell, which is specialized to encourage regeneration. These cells execute a repair program, a sequence of changes involving myelin autophagy, expression of cytokines that call in macrophages for later stages of myelin clearance, activation of trophic factor expression and cellular elongation and branching to form regeneration tracks, called Bungner Bands.

If Schwann cells are prevented from associating with axons, the axons die. Regenerating axons will not reach any target unless Schwann cells are there to support them and guide them