Peripheral nervous system regeneration Neuroregeneration

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guillain–barré syndrome – nerve damage


neuroregeneration in peripheral nervous system (pns) occurs significant degree. axonal sprouts form @ proximal stump , grow until enter distal stump. growth of sprouts governed chemotactic factors secreted schwann cells (neurolemmocytes). injury peripheral nervous system elicits migration of phagocytes, schwann cells, , macrophages lesion site in order clear away debris such damaged tissue. when nerve axon severed, end still attached cell body labeled proximal segment, while other end called distal segment. after injury, proximal end swells , experiences retrograde degeneration, once debris cleared, begins sprout axons , presence of growth cones can detected. proximal axons able regrow long cell body intact, , have made contact schwann cells in endoneurial channel or tube. human axon growth rates can reach 1 mm/day in small nerves , 5 mm/day in large nerves. distal segment, however, experiences wallerian degeneration within hours of injury; axons , myelin degenerate, endoneurium remains. in later stages of regeneration remaining endoneurial tube directs axon growth correct targets. during wallerian degeneration, schwann cells grow in ordered columns along endoneurial tube, creating band of büngner (bob) protects , preserves endoneurial channel. also, macrophages , schwann cells release neurotrophic factors enhance re-growth.








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