Besides apoptosis, cells may die for accidental reasons, such as rather common local or diffuse ischemia due to a lack of oxygen. Such accidental cell death due to whatever reason (ischemia, harmful physical factors, cytotoxic posions, inflammation, etc.) is called necrosis.

The cardiac muscle cell in the image has gone through prolonged (45 minutes) ischemia episode, since the heart was in an animal’s cadaver over this period of time. Such conditions lead to total cell necrosis in the myocardium, so that the cell damage can be studied at its finest. In a living body, necrosis, unlike apoptosis, involves cell groups and not solitary cells; this damage causes a marked inflammatory reaction in tissues. The image demonstrates that the cell death is accompanied by massive destruction of mitochondria #1, #2, #3 and myofibrils #1, #2, as well as by some specific changes of the nucleus. Such a nucleus is called pyknotic as it is being considerably reduced, condensed, and is also easily and intensively stained by histological dyes. During necrosis, a lysosomal component #1, #2 of cells is usually activated while hydrolytic enzymes released into the cytoplasm destroy the organelles.