Neuromuscular

Fiber Type Disproportion


Type 1 Fiber Smallness: Differential Diagnosis


INFANT
H+E
H&E stain
ATP9.4
ATPase pH 9.4 stain

CHILD (5 years)

ATPase H&E stain
Fiber size: Bi-modal variation


ATPase pH 9.4 stain
  • Type 1 muscle fibers (Light) are small
  • Type 2 muscle fibers (Dark): Largest, & Some small, fibers


ATPase pH 4.3 stain
  • Type 1 muscle fibers (Dark) are small
  • Type 2 muscle fibers (Light) are the largest
  • Type 2C fibers (Intermediate): Small or Large


ATPase pH 4.6 stain
  • Type 1 muscle fibers (Dark) are small

CHILD (12 years)

ATPase H&E stain
Fiber size: Bi-modal variation


ATPase pH 9.4 stain
  • Type 1 muscle fibers (Light) are small
  • Type 2 muscle fibers (Dark): Largest, & Some small, fibers


ATPase pH 4.3 stain
  • Type 1 muscle fibers (Dark) are small
  • Type 2 muscle fibers (Light) are mostly large and occasionally small

Co-Expression of Fast & Slow Myosin in Same Larger Muscle Fibers

Small Muscle fibers: Stain only for Slow Myosin (Type I)

Fast myosin in muscle fibers

Slow myosin in muscle fibers

Fiber Predominance: Type 2


ATPase pH 9.4 stain

ATPase pH 4.3 stain

See
  Fiber type disorders
  Fiber type properties

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10/31/2016