General description
  Type 1 small

Nemaline Rod Pathology

  • Light microscopy
    • Rods best visualized with Gomori trichrome stain
    • Dark blue structures
    • Most in muscle fiber cytoplasm
  • Contain
    • Z-line like material
    • α-actinin, actin & tropomyosin ± desmin at the periphery
  • Located in sarcoplasm: Often in regions with disrupted sarcomere structure
  • Occur in
  • Similar appearance & staining to: Cytoplasmic bodies
  • Also see: Rods or Cytoplasmic bodies in target fibers

Nemaline rod myopathy: Infantile

Gomori trichrome
Nemaline rods in gastrocnemius muscle from 4 month old child

No nemaline rods in quadriceps muscle from same child biopsied at 2 months of age

Nemaline rod myopathy, Infantile: Toluidine blue stains

Nemaline rod myopathy, Infantile: Other stains

H&E stain
Muscle fiber sizes: Varied

H&E stain

H& E stain
Muscle fiber size: Varied
Refractile rods can be seen

ATPase stain, pH 9.4
Type I muscle fiber predominance

H& E stain

Rods: Actin stain

Phalloidin staining for actin
Focal (bright green), large and small aggregates of actin are present in some muscle fibers

Phalloidin staining for actin

Nemaline Rod Ultrastructure

Infantile-onset Rod myopathy

From: R Schmidt


From E Hardeman
Electron microscopy of rods from Z-lines in Met9Arg αTMslow mouse

Nemaline rod myopathy, infant (8 months of age): Type 1 muscle fiber smallness

Rods: More prominent in smaller muscle fibers

Gomori trichrome

ATPase pH 9.4
Type 1 muscle fibers: Small (Pale)

Muscle fiber sizes: Bimodal

Internal architecture of muscle fibers: Irregular

Rod Myopathy: Congenital + Arthrogryposis

H&E stain
Fiber sizes: Bimodal distribution

Gomori trichrome stain
  Dark-stained: Punctate or Clustered regions, Often sub-sarcolemmal
  More common in smaller muscle fibers

Gomori trichrome stain

Gomori trichrome stain

ATPase pH 9.4 stain
Fiber types
  Type 1 fibers: Usually small
  Type 2 fibers: Larger; Abnormal intermediate staining (2C) at ATPase pH 4.3

ATPase pH 4.3 stain

NADH stain

Rods: In clusters in muscle fibers

Toluidine blue stain

Toluidine blue stain

Nemaline rod myopathy, Childhood: 2 Different patterns

Rods: In smaller muscle fibers

GT stain

ATPase stain, pH 9.4
Type I muscle fibers: Smaller than type II

Rods: In small & large muscle fibers

GT stain
Type I predominance

ATPase stain, pH 9.4
Fiber size variation: Bimodal distribution

H&E stain

Rods: Adult nemaline myopathy
  Several patterns

Rods: Larger & Aggregated
Gomori trichrome

Rods: Small & Diffusely distributed in some muscle fibers
  Myopathic features: Varied muscle fiber size; Internal nuclei; Endomysial connective tissue increased

Gomori trichrome

H&E stain

Return to Rod myopathies