Chapter 9 Causes of cell injury
There is a wide variety of agents that can cause cell damage. Whatever the cause, if the injury is relatively minor the cell may be able to repair itself and return to normal. This is reversible injury; it may be characterized morphologically at the light microscopic level by cellular swelling (called hydropic change or vacuolar degeneration) or by fatty change, and at the ultrastructural level by blebbing of the cell membrane, abnormalities of mitochondria and endoplasmic reticulum, and disaggregation of nuclear structures. However, if the initial insult to the cell is severe or prolonged, an irreversible injury will occur and the cell will die by apoptosis or necrosis. The factors that determine which pathway is followed are complex and not entirely understood but it seems that damage to cell membranes promotes death by necrosis rather than apoptosis. These pathways are illustrated in Fig. 3.9.1 (see also Ch. 10).
