Difference between revisions of "Muscle Regeneration"

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{{toplink
 
|backcolour =CDE472
 
|linkpage =Musculoskeletal System - Pathology
 
|linktext =Musculoskeletal System
 
|maplink = Musculoskeletal System (Content Map) - Pathology
 
|pagetype =Pathology
 
|sublink1=Muscles - Pathology
 
|subtext1=MUSCLES
 
}}
 
<br>
 
 
===Response to injury===
 
===Response to injury===
  
 
*Limited array of ways in which to respond to injury
 
*Limited array of ways in which to respond to injury
**[[Muscles Degenerative - Pathology#Degeneration|Degeneration]]
+
**[[:Category:Muscles - Degenerative Pathology|Degeneration]]
**[[Muscles Degenerative - Pathology#Necrosis|Necrosis]]
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**[[Muscle Necrosis|Necrosis]]
**[[Muscles - normal#Regeneration|Regeneration]]
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**Regeneration
**[[Muscles Degenerative - Pathology#Atrophy|Atrophy]]
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**[[Muscle Atrophy|Atrophy]]
**[[Muscles Hyperplastic and Neoplastic - Pathology#Hypertrophy|Hypertrophy]]
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**[[Muscle Hypertrophy|Hypertrophy]]
  
 
*Large number of factors indicing the changes above, e.g.:
 
*Large number of factors indicing the changes above, e.g.:
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**Nutritional deficiencies
 
**Nutritional deficiencies
 
**Ichaemia
 
**Ichaemia
**[[Muscles Developmental - Pathology|Hereditary diseases]]
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**[[:Category:Muscles - Developmental Pathology|Hereditary diseases]]
  
  
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**If these conditions are not met (e.g. severe thermal damage) '''fibrosis''' will occur
 
**If these conditions are not met (e.g. severe thermal damage) '''fibrosis''' will occur
 
*Stages:
 
*Stages:
#Nuclei in [[Muscles Degenerative - Pathology#Necrosis|necrotic segement]] disappear, hyalinased sarcoplasm due to loss of normal myofibrillar structure, may separate from adjacent normal myofibrils and/or [[Muscles Degenerative - Pathology#Calcification|mineralise]]
+
#Nuclei in [[Muscle Necrosis|necrotic segement]] disappear, hyalinased sarcoplasm due to loss of normal myofibrillar structure, may separate from adjacent normal myofibrils and/or [[Muscle Calcification|mineralise]]
 
#Monocytes from capillaries -> macrophages in necrotic portion, satellite cells swell -> vesicular with prominent nucleoli -> mitosis (within 1-4 days after initial injury)
 
#Monocytes from capillaries -> macrophages in necrotic portion, satellite cells swell -> vesicular with prominent nucleoli -> mitosis (within 1-4 days after initial injury)
 
#Satellite cells move to centre
 
#Satellite cells move to centre
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*Regeneration by '''budding'''
 
*Regeneration by '''budding'''
 
**When conditions are not optimal, disrupted sacrolemma
 
**When conditions are not optimal, disrupted sacrolemma
**E.g. injection of irritating substance, trauma, [[Muscles Degenerative - Pathology#Ischaemia|infarction]]
+
**E.g. injection of irritating substance, trauma, [[Muscle Ischaemia|infarction]]
 
**Myoblasts proliferate -> sacrolamma bulges from cut part -> club-shaped with numerous central nuclei = muscle giant cells
 
**Myoblasts proliferate -> sacrolamma bulges from cut part -> club-shaped with numerous central nuclei = muscle giant cells
 
*Monophasic lesions - all at same phase above
 
*Monophasic lesions - all at same phase above
  
===Rigor Mortis===
 
  
*Muscles remain biochemically active after the death of an animal
 
*Following a period of relaxation, contraction and stiffening occurs
 
*Due to deficiency of ATP releasing myosin heads from their binding sites at end of power stroke
 
*Onset faster in ATP deprived animals (starvation, hunting, tetanus...)
 
*May be absent in cachetic animals
 
*Disappears due to autolysis or putrefaction
 
*See [[General Pathology - Post-Mortem Change#Rigor Mortis|general pathology]]
 
  
 
+
[[Category:Muscles - Pathology]]
 
 
**Damage occured at one time, e.g. trauma or one toxin exposure
 
*Multiphasic lesions - different stages as described above
 
**Ongoing damage, e.g. vitamin E - selenium deficiency, continuous exposure to toxin
 

Latest revision as of 11:41, 7 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