Neuromuscular

Denervation with Reinnervation, Chronic Inactive

Muscle Fiber Type Grouping

  Type grouping
    Comparative ATPase stains
    Staining patterns
  Associated with, & Caused by, Axon Growth
    Regeneration: Large fiber type groups
    Collateral sprouting: Small fiber type groups
Denervation + Reinnervation, Chronic: Fiber Type Grouping

 

ATPase pH 9.4 stain
ATPase pH 9.4 stain

ATPase pH 9.4 stain
Normal Pattern
"Checkerboard" distribution of
  Types I (Light) II (Dark)
    muscle fibers
Fiber Type Grouping
  Type I & Type II muscle fibers: Clustered in groups.
  Type II fibers in this biopsy are mostly type IIB (ATPase pH 4.6 stain, below right).

ATPase pH 4.3 stain
ATPase pH 4.6 stain
Fiber Type Grouping: Staining Patterns

ATPase pH 9.4 stain
Fiber Type Groups: Denervation & Reinnervation
Clusters of Type I & II fibers
No small muscle fibers or ongoing denervation

NADH stain

ATPase pH 4.3 stain
Fiber type grouping
Incomplete fiber type switching: Varied fiber types within a single group

ATPase pH 4.3 stain
Fiber type grouping with incomplete type switching: 2C fibers in clusters of grouped muscle fibers

ATPase pH 4.3 stain

Fiber Type Grouping: Comparative ATPase staining

Incomplete Fiber Type Switching within a region of Type Grouping
  Fascicle in center of image (Dark arrows) has all type 2 fibers on ATPase pH 9.4 & 4.3, but varied subtypes at ATPase pH 4.6

ATPase pH 9.4 stain

ATPase pH 4.3 stain
Fiber Type Switching during Grouping: Compare to ATPase pH 9.4 & 4.3
  Incomplete Type Switching
    Varied colors of type 2 fibers in individual groups (Black arrow)
  Complete Type Switching
    All fibers in a group are Type 2A (White arrow) or 2B (Red arrow)

ATPase pH 4.6 stain

Axon Loss


Toluidine blue stained plastic section

Nerve: Chronic Inactive Axon Loss (Denervation)
Also see: Ongoing or Active Denervation
Return to Neuromuscular Syndromes

7/27/2023