Trunk Muscles

H&E stain
Fiber size: Mild variation
Endomysial connective tissue: Normal
Perimysial Vessels: Normal

H&E stain

Congo red stain
Nuclei: Normally present at periphery of muscle fibers

Gomori trichrome stain
Internal architecture: Mildy prominent or coarse

VvG stain

Internal architecture

NADH stain
Internal architecture
  Varied degrees of coarseness & irregularity
  "Alveolar" fibers: Similar to those seen in CACNA1S congenital myopathy

NADH stain
Some muscle fibers have
  Internal clear regions
  Irregular internal architecture

NADH stain

ATPase pH 9.4 stain
Fiber types
  Some fascicles, or entire muscles, can have marked type I fiber predominance
  Fiber type proportions can vary among fascicles

ATPase pH 9.4 stain

No fiber type grouping

ATPase pH 9.4 stain

Alkaline phosphatase stain
Endomysial capillaries
  Some, more than in limb muscles, stain for alkaline phosphatase

Alkaline phosphatase stain

Muscle: Other Structures

Muscle structures
    Arteries: Fibrillar internal layer
    Veins: (Black arrows): Wall may have no fibrils (Above) or many curved fibrils (Below)
    Endomysial capillaries (White arrow)
  Spindle (Contains small round muscle fibers)
  Intramuscular nerve (Myelinated axons are dark-stained)
  Perimysium: Connective tissue between fasciclas (Pink-stained): Contains irregular fibrils
    Vascular perimysium: Contains intermediate-sized arteries & veins + lymphatics
    Avascular perimysium: Contains no vessels

Avascular Perimysium

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