The MAJOR histological feature of MI is?
For 2 hours after the onset of myocardial infarction (as indicated by onset of pain or arrhythmias and shock), there are no morphologic changes in the necrotic myocardial fibers. At about 2 hours, electron microscopic changes appear (swelling of mitochondria endoplasmic reticulum, fragmentation of myofibrils). Light microscopic changes may appear in 4-6 hours but are rarely detectable with ceainty before 12-24 hours. Coagulative necrosis of the myocardial fibers is recognized by nuclear pyknosis and dark pink staining of the cytoplasm and loss of striations in the cytoplasm.Coagulative necrosis is the most common pattern of necrosis characterized by conversion of cell to acidophilic and opaque gravestone. This pattern of necrosis results most commonly from sudden severe ischemia in organs such as kidney, hea and adrenal glands. Ref: Chandrasoma P., Taylor C.R. (1998). Chapter 23. The Hea: III. Myocardium & Pericardium. In P. Chandrasoma, C.R. Taylor (Eds), Concise Pathology, 3e.
Liquefactive necrosis
Fibrinoid necrosis
Coagulative necrosis
Contraction band necrosis