Neuromuscular

PERIPHERAL NERVE REGENERATION

Axons
  Clusters
  Thin myelination
Pseudo-onion bulb
Muscle

REGENERATING CLUSTERS
Nerves with clusters of regenerated (thinly-myelinated) axons
  Clusters of 2 to 12 axons, thinly myelinated for size
  There is also axon loss
    Fewer large & small myelinated axons
    Büngner bands
  Clusters of regenerating axons often occur with chronic changes in muscle
    Partial denervation
    Fiber type grouping


Toluidine blue stain

Ultrastructure: From Robert E Schmidt MD



Toluidine blue stain
Regenerating Clusters
  Thinly myelinated large axons have similar degrees of myelination


POST-REGENERATION
  Regenerated axons: Usually thinly myelinated with short internodal length
  Thinly myelinated large axons may comprise
    Most myelinated axons in a nerve (Above) or
    Scattered axons (Below; arrows)
  Myelinated axons: Reduced numbers

Toluidine blue stain: From Chunyu Cai
Thinly myelinated large axons: Scattered or Clustered

Toluidine blue stains of plastic nerve sections


POST-REGENERATION: Few thickly myelinated large axons

VvG stain

POST-REGENERATION: Reduced numbers of large axons

Neurofilament stain

POST-REGENERATION: Proliferation of non-myelinating Schwann cells

NCAM stain

Pseudo Onion bulb
Thinly myelinated large axon: Surrounded by a pseudo onion bulb (Multiple Schwann cell processes)

Post-Axon-Regeneration: Muscle
  Fiber Type Grouping

Fiber type grouping with incomplete type switching: 2C fibers in clusters of grouped muscle fibers

ATPase pH 4.3 stain

ATPase pH 4.3 stain

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2/13/2017