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from cells or pooled from lipoproteins in crystalline form( cholesterol clefts )as a result of
 
from cells or pooled from lipoproteins in crystalline form( cholesterol clefts )as a result of
 
haemorrhage or tissue damage.
 
haemorrhage or tissue damage.
4. Mucoid ( mucinous, myxomatous ) degeneration - changes in epithelial tissue
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or ground substance (matrix) produced by fibroblasts in connective tissue..
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This is an extracellular phenomenon of some specific cells. They tend to show a bluish tinge
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in H&E stained sections.
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a. Epithelium - specifically the goblet cells of wet mucous membranes and the mucous
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glands themselves. It is a beneficial reaction and is not really degeneration, but an increased
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production of mucin. Their secretions are important as lubricants and protective substances
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soothing inflamed surfaces, entrapping and diluting harmful agents, carrying specific
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antibodies against infectious agents, and providing a means for their removal.
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b. Connective tissue - the mucin here forms part of the ground substance between the cells
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( fibroblasts ) producing it. In some circumstances, there appears to be a disturbance in the
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metabolism of the fibroblasts which produce the mucin and the ground substance takes on a
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bluish hue in H&E sections.
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The common example is the
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mucoid ( myxomatous, myxoid )
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degeneration that occurs in the
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heart valves of middle-aged and
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older dogs. It occurs primarily in the
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mitral valve and is responsible for a
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condition specific for this species
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called endocardiosis.
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It is important and results in slowly
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developing heart failure due to the
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inability of a heart with swollen
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misshapen valves to effectively pump
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blood from the left ventricle out into
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the systemic circulation. A substantial
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portion of the blood passes back into
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the left
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atrium and compromises the filling of the atrium from the pulmonary vein. This leads to
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back pressure on the pulmonary capillaries with oedema formation in the lungs. This
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reduces the oxygenation of blood leading to exercise intolerance and may be heard as moist
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sounds on auscultation of the lungs. Eventually, this failure of the left side compromises the
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function of the right side and there is also pooling of blood in the venous system i.e. in the liver.
      
===Mucoid Degeneration===
 
===Mucoid Degeneration===
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