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Ring fibers (Ringbinden; Spiral Annulets): Circumferential Sarcomere Misorientation

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Ring Fiber

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NADH stain

H&E stain

Congo red stain

Ring fibers

• Stains
  • NADH & AMPDA: Ring of striations, perpendicular to normal orientation, around circumference of muscle fiber
  • H & E: Internal, ring-shaped, dark-staining regions; Often in smaller fibers
  • Congo red: "Amorphous" ring in a muscle fiber with paler central region
• Clinical correlations
  • Poorly defined
  • Associated disorders
    • Chronic myopathies
    • Myotonic Dystrophy
    • Tenotomy
    • Muscle fiber regeneration

NADH stain

AMPDA stain

NADH stain

Dark staining sarcoplasmic pad around rim of fiber (Right)

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Ring Fiber
  Circumferential sarcomeres around normally oriented sarcomere cross-sections
  Sarcoplasm with abundant Mitochondria surrounds most of fiber
  Lipofuscin granule (Top left)

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Ring Fibers
  Circumferentially oriented sarcomeres (Top)
Ring Fibers
  Circumferentially oriented sarcomeres (Top)

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7/7/2024