Difference between revisions of "Muscle Regeneration"

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**[[Muscles Degenerative - Pathology#Degeneration|Degeneration]]
 
**[[Muscles Degenerative - Pathology#Degeneration|Degeneration]]
 
**[[Muscles Degenerative - Pathology#Necrosis|Necrosis]]
 
**[[Muscles Degenerative - Pathology#Necrosis|Necrosis]]
**[[Muscle Regeneration - Anatomy & Physiology|Regeneration]]
+
**Regeneration
 
**[[Muscles Degenerative - Pathology#Atrophy|Atrophy]]
 
**[[Muscles Degenerative - Pathology#Atrophy|Atrophy]]
 
**[[Muscles Hyperplastic and Neoplastic - Pathology#Hypertrophy|Hypertrophy]]
 
**[[Muscles Hyperplastic and Neoplastic - Pathology#Hypertrophy|Hypertrophy]]

Revision as of 17:43, 3 March 2011

Response to injury

  • Large number of factors indicing the changes above, e.g.:


  • Specific diagnosis is often not possible based on morphological or histological features alone
  • Additional tests, clinical information and history are often required

Regeneration

Muscle regeneration (Image sourced from Bristol Biomed Image Archive with permission)
  • Skeletal muscle myofibres have substantial regenerative ability
  • Success depends on:
    • An intact sarcolemmal tube - to act as a support and guide
    • Availability of satellite cells - to act as progenitor cells for new sarcoplasm production
    • Macrophages to clear up cell debris
    • If these conditions are not met (e.g. severe thermal damage) fibrosis will occur
  • Stages:
  1. Nuclei in necrotic segement disappear, hyalinased sarcoplasm due to loss of normal myofibrillar structure, may separate from adjacent normal myofibrils and/or mineralise
  2. Monocytes from capillaries -> macrophages in necrotic portion, satellite cells swell -> vesicular with prominent nucleoli -> mitosis (within 1-4 days after initial injury)
  3. Satellite cells move to centre
  4. Macrophages clear the sacrolemmal tube, plasmalemma disappears, shape maintained by basal lamina
  5. Satellite cells -> myoblasts (contain myosin) -> fuse forming myotubes with row of central nuclei; cytoplasmic processes fusing
  6. Growing and differentiating fibre, striations appear - formation of sarcomeres
  7. Nuclei move to peripheral position (2-3 weeks after initial injury)
  • Regeneration by budding
    • When conditions are not optimal, disrupted sacrolemma
    • E.g. injection of irritating substance, trauma, infarction
    • Myoblasts proliferate -> sacrolamma bulges from cut part -> club-shaped with numerous central nuclei = muscle giant cells
  • Monophasic lesions - all at same phase above