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Muscles Degenerative - Pathology (view source)

Revision as of 20:13, 18 August 2008

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*Cloudy swelling, hydropic, vacuolar, granular and fatty change
 
*Cloudy swelling, hydropic, vacuolar, granular and fatty change
 
*Occur following many different types of insult and are usually '''segmental'''
 
*Occur following many different types of insult and are usually '''segmental'''
−
*If regeneration does not occur after formation of small vacuoles, [[Muscles - degenerative#Necrosis|necrosis]] follows
+
*If regeneration does not occur after formation of small vacuoles, [[Muscles Degenerative - Pathology#Necrosis|necrosis]] follows
 
**Vacuolation -> floccular degeneration -> granular degeneration -> [[General Pathology - Degenerations and Infiltrations#Hyaline Degeneration|hyaline]] and [[Zenker degeneration|Zenker’s degeneration]]
 
**Vacuolation -> floccular degeneration -> granular degeneration -> [[General Pathology - Degenerations and Infiltrations#Hyaline Degeneration|hyaline]] and [[Zenker degeneration|Zenker’s degeneration]]
 
*[[General Pathology - Degenerations and Infiltrations#Vacuolar Degeneration|'''Vacuolar degeneration''']]:  
 
*[[General Pathology - Degenerations and Infiltrations#Vacuolar Degeneration|'''Vacuolar degeneration''']]:  
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***Bundles of dense fibrous connective tissue
 
***Bundles of dense fibrous connective tissue
 
***May contain accumulations of cartilage, bone or calcium
 
***May contain accumulations of cartilage, bone or calcium
−
**Hyperplastic connective tissue -> compression of adjacent skeletal muscle -> [[Muscles - degenerative#Atrophy|atrophy]]
+
**Hyperplastic connective tissue -> compression of adjacent skeletal muscle -> [[Muscles Degenerative - Pathology#Atrophy|atrophy]]
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**Normal portion of fibre may detach from necrotic part -> retraction caps
 
**Normal portion of fibre may detach from necrotic part -> retraction caps
 
**Infarction may cause '''discoid degeneration''' - necrotic fibres detach at '''Z lines'''
 
**Infarction may cause '''discoid degeneration''' - necrotic fibres detach at '''Z lines'''
−
**May [[Muscles - degenerative#Calcification|mineralise]]
+
**May [[Muscles Degenerative - Pathology#Calcification|mineralise]]
 
*[[Zenker degeneration|'''Zenker's degeneration''']] - secondary to systemic disease
 
*[[Zenker degeneration|'''Zenker's degeneration''']] - secondary to systemic disease
 
**Scattered small segments of necrosis and fast regeneration
 
**Scattered small segments of necrosis and fast regeneration
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**Grossly:
 
**Grossly:
 
***Pale areas with ill-defined borders
 
***Pale areas with ill-defined borders
−
***May involve very extensive [[Muscles - degenerative#Necrosis|necrosis]]
+
***May involve very extensive [[Muscles Degenerative - Pathology#Necrosis|necrosis]]
 
**Histologically:
 
**Histologically:
 
***Segmental necrosis, no calcification
 
***Segmental necrosis, no calcification
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****Pale streaks, mostly in hind limbs
 
****Pale streaks, mostly in hind limbs
 
***Histologically:
 
***Histologically:
−
****[[Muscles - degenerative#Necrosis|Segmental necrosis]]
+
****[[Muscles Degenerative - Pathology#Necrosis|Segmental necrosis]]
 
****Possibly [[Muscles - normal#Regeneration|regeneration]] in surviving animals
 
****Possibly [[Muscles - normal#Regeneration|regeneration]] in surviving animals
 
***Can cause rapid onset recumbency and potentially death  
 
***Can cause rapid onset recumbency and potentially death  
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*'''Mycotoxins'''
 
*'''Mycotoxins'''
 
**Metabolites cause persistent tremors
 
**Metabolites cause persistent tremors
−
**Lesions in skeletal muscle only, possibly secondary to sustained contractions (similar to [[Muscles - degenerative#Exertional myopathies|exertional myopathy]])
+
**Lesions in skeletal muscle only, possibly secondary to sustained contractions (similar to [[Muscles Degenerative - Pathology#Exertional myopathies|exertional myopathy]])
 
**Histologically:
 
**Histologically:
−
***Tiny foci of [[Muscles - degenerative#Necrosis|segmental necrosis]]
+
***Tiny foci of [[Muscles Degenerative - Pathology#Necrosis|segmental necrosis]]
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*[[Adrenal Glands - Pathology#Adrenal Hyperfunction|Hyperadrenocorticism]]  
 
*[[Adrenal Glands - Pathology#Adrenal Hyperfunction|Hyperadrenocorticism]]  
 
**Muscle weakness is a clinical sign
 
**Muscle weakness is a clinical sign
−
**-> [[Muscles - degenerative#Atrophy|muscle atrophy]]  
+
**-> [[Muscles Degenerative - Pathology#Atrophy|muscle atrophy]]  
 
***Type II myofibre atrophy is non-specific
 
***Type II myofibre atrophy is non-specific
 
***Type IIB myofibre atrophy is preferential in hyperadrenocorticism
 
***Type IIB myofibre atrophy is preferential in hyperadrenocorticism
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**Vitamin E usually mops up OFRs
 
**Vitamin E usually mops up OFRs
 
**Selenium as part of glutathione peroxidase neutralises effects of OFRs  
 
**Selenium as part of glutathione peroxidase neutralises effects of OFRs  
−
**If Vit E or Se are deficient -> the balance shifts to membrane damage, calcium entry and mitochondrial damage -> cell swells and dies -> segmental muscle [[Muscles - degenerative#Necrosis|necrosis]]
+
**If Vit E or Se are deficient -> the balance shifts to membrane damage, calcium entry and mitochondrial damage -> cell swells and dies -> segmental muscle [[Muscles Degenerative - Pathology#Necrosis|necrosis]]
 
*Grossly:
 
*Grossly:
 
**Lesions are bilaterally symmetrical in hard working muscles (vary with species)
 
**Lesions are bilaterally symmetrical in hard working muscles (vary with species)
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**Pigs also have lesions in their [[Myocardial - Pathology#Hyaline degeneration|heart]] and [[Liver - general pathology#Hepatosis dietica|liver]]
 
**Pigs also have lesions in their [[Myocardial - Pathology#Hyaline degeneration|heart]] and [[Liver - general pathology#Hepatosis dietica|liver]]
 
*Histologically:
 
*Histologically:
−
**[[Muscles - degenerative#Necrosis|Segmental necrosis]] +/- [[Muscles - degenerative#Calcification|calcification]] and [[Muscles - normal#Regeneration|regeneration]]
+
**[[Muscles Degenerative - Pathology#Necrosis|Segmental necrosis]] +/- [[Muscles Degenerative - Pathology#Calcification|calcification]] and [[Muscles - normal#Regeneration|regeneration]]
 
**Multifocal and multiphasic lesions
 
**Multifocal and multiphasic lesions
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***Salmon pink muscles -> dark, moist, swollen +/- pale streaks
 
***Salmon pink muscles -> dark, moist, swollen +/- pale streaks
 
**Histologically:
 
**Histologically:
−
***Segmental myofibre [[Muscles - degenerative#Necrosis|necrosis]]
+
***Segmental myofibre [[Muscles Degenerative - Pathology#Necrosis|necrosis]]
 
****Multifocal and monophasic, but may be multiphasic if repeated bouts
 
****Multifocal and monophasic, but may be multiphasic if repeated bouts
 
***Both, type IIA and IIB fibres affected; type IIB preferentially affected in acute disease
 
***Both, type IIA and IIB fibres affected; type IIB preferentially affected in acute disease
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*Histologically:
 
*Histologically:
 
**Segmental hypercontraction
 
**Segmental hypercontraction
−
**Monophasic, multifocal [[Muscles - degenerative#Necrosis|segmental necrosis]]
+
**Monophasic, multifocal [[Muscles Degenerative - Pathology#Necrosis|segmental necrosis]]
 
*Inherited
 
*Inherited
 
*Triggered by halothane anaesthesia, stress of handling, transportation or slaughter
 
*Triggered by halothane anaesthesia, stress of handling, transportation or slaughter
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===Ischaemia===
 
===Ischaemia===
   −
*Firstly [[Muscles - degenerative#Necrosis|segmental necrosis]]  
+
*Firstly [[Muscles Degenerative - Pathology#Necrosis|segmental necrosis]]  
 
*-> death of satellite cells  
 
*-> death of satellite cells  
 
**Causes [[Muscles - normal#Regeneration|regeneration]] but myoblast precursors have to be recruited from viable fibres
 
**Causes [[Muscles - normal#Regeneration|regeneration]] but myoblast precursors have to be recruited from viable fibres
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**Infarction from embolism is rare due to collateral circulation
 
**Infarction from embolism is rare due to collateral circulation
 
**Extension of infarcts depends on size of vessels occluded
 
**Extension of infarcts depends on size of vessels occluded
−
***Small capillaries -> segmental [[Muscles - degenerative#Necrosis|necrosis]]
+
***Small capillaries -> segmental [[Muscles Degenerative - Pathology#Necrosis|necrosis]]
 
***Large arteries -> whole muscle areas, including sattelite cells, are killed
 
***Large arteries -> whole muscle areas, including sattelite cells, are killed
 
**Healed by fibrosis
 
**Healed by fibrosis
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**Compression of myofibres
 
**Compression of myofibres
 
**Secondary from haemorrhage (bruising)
 
**Secondary from haemorrhage (bruising)
−
***May increase muscle pressure -> [[Muscles - degenerative#Ischaemia|ischaemia]] -> [[Muscles - degenerative#Necrosis|necrosis]]
+
***May increase muscle pressure -> [[Muscles Degenerative - Pathology#Ischaemia|ischaemia]] -> [[Muscles Degenerative - Pathology#Necrosis|necrosis]]
 
**Partial rupture - ''e.g.'' of diaphragm in road traffic accident
 
**Partial rupture - ''e.g.'' of diaphragm in road traffic accident
 
**Complete rupture - ''e.g.'' quadriceps of racing greyhounds
 
**Complete rupture - ''e.g.'' quadriceps of racing greyhounds
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