Neuromuscular

TERMINAL MOTOR AXONS & NEUROMUSCULAR JUNCTIONS

Acrylamide
Atrophy
Botulinum toxin
Collateral sprouting
Dimethyaminopropionitrile (DMAPN)
Normal

Normal


Human: Silver-P0-Esterase stain

Rat: Silver-P0-Esterase stain

Normal neuromuscular junctions
  • Axon stained black (Silver), innervates a single NMJ
  • Myelin is rust colored (P0 antibody)
  • NMJ region is blue (Esterase stain)

Collateral sprouting


Silver-P0-Esterase stain

Collateral sprouting in patient with ALS
  • Terminal branches from a single axon innervate several neuromuscular junctions
  • Grouped atrophy: Occurs when reinnervating axon dies or becomes inactive
  • Fiber type grouping: Occurs with reinnervation by intact axons
    • Mechanisms
      • Collateral sprouts: From terminal (Ultraterminal sprout) or preterminal (Preterminal sprout from node of Ranvier) axon
      • Regenerating axons: After damage & regrowth
    • ALS: More common with slowly progressive or chronic disease


Silver-P0-Esterase stain

Terminal loss of myelin on an atrophic axon

Botulinum


Silver-Esterase stain
Botulinum treatment (Rat)
Enlargement of the NMJ with increased terminal branching of the motor axon


Terminal axons at Neuromuscular junctions (Rat)
Botulinum toxin induces enlargement of NMJs (middle)
  & ultraterminal sprouts from nerve terminals (middle & top)

Acrylamide


Silver-Esterase stain

Acrylamide intoxication (Rat)
Enlargement motor nerve terminals

Dimethyaminopropionitrile


Silver-Esterase stain

Dimethyaminopropionitrile (DMAPN) intoxication (Rat)
Ultraterminal sprout
Swelling in sprout & axon terminal branches in NMJ


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4/17/2013