Normal Heart
Myocardial Infarction
Two to three days after an MI, the myocytes show that they are irreversibly damaged. They've lost their nuclei. PMNs (polymorphonuclear leukocytes) are the first inflammatory cells on the scene. They will begin to clear away the necrotic tissue. Later the macrophages will finish the job. These dying myocytes will eventually be replaced with scar tissue.

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Viral Myocarditis
Notice that the nuclei are still intact in the myocytes. The inflammatory cells are lymphocytes. Remember: bacterial infections & acute processes elicit PMNs while viral infections elicit lymphocytes and other mononuclear cells.

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