Glycogen Infiltration

• Glycogen is normally present in substantial amounts in the liver and muscle.
  • Is a readily utilisable source of energy.
• Moderate glycogen infiltration in the liver:
  • Grossly - doesn't have much effect.
  • Histologically - shows up as foamy cytoplasmic vacuoles, similar to that of fat.
• Some conditions may result in an increase in glycogen deposits.
  • Diabetes mellitus
    • Gives an increase in hepatic glycogen stores.
    • May be overshadowed by the increased fat in the hepatocytes, and therefore difficult to see.
      • Renal tubular deposits are more easily observed.
  • Excessive glucocorticoids
    • Could be due to:
      • Hyperadrenocortism
      • Animals being maintained on glucocorticoid therapy over a long period of time.
        • Has more dramatic effect.
    • Huge amounts of glycogen infiltration.
      • Liver appears larger and paler.
      • Vacuoles may be so extensive that the rest of the cytoplasm appear as pink strands passing from the nucleus to the plasma membrane.
        • A "feathery appearance" or "web-like effect".
  • Glycogen storage diseases
    • Due to an inherited deficiency of an enzyme required for the breakdown of glycogen to glucose.
      • Cells continuously accumulate glycogen.
    • Seen in all tissues of the body but exerts its major effect in the CNS.
• Selective staining must be employed to distinguish glycogen vacuoles from fatty vacuoles in the liver.
  • Alcohol fixation is preferred.
  • Best's Carmine is the commonly used stain.
    • Stains the intracellular glycogen red.

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