   necrosis (from the greek Î½Î­ÎºÏÏÏÎ¹Ï "death, the stage of dying, the act of killing" from Î½ÎµÎºÏÏÏ "dead") is a form of cell injury that results in the premature death of cells in living tissue by autolysis. necrosis is caused by factors external to the cell or tissue, such as infection, toxins, or trauma that result in the unregulated digestion of cell components. in contrast, apoptosis is a naturally occurring programmed and targeted cause of cellular death. while apoptosis often provides beneficial effects to the organism, necrosis is almost always detrimental and can be fatal.  cells that die due to necrosis do not follow the apoptotic signal transduction pathway but rather various receptors are activated that result in the loss of cell membrane integrity and an uncontrolled release of products of cell death into the extracellular space. this initiates in the surrounding tissue an inflammatory response which prevents nearby phagocytes from locating and eliminating the dead cells by phagocytosis. for this reason, it is often necessary to remove necrotic tissue surgically, a procedure known as debridement. untreated necrosis results in a build-up of decomposing dead tissue and cell debris at or near the site of the cell death. a classic example is gangrene. ==classification== structural signs that indicate irreversible cell injury and the progression of necrosis include dense clumping and progressive disruption of genetic material, and disruption to membranes of cells and organelles. ===morphological patterns=== there are five distinctive morphological patterns of necrosis: # coagulative necrosis is characterized by the formation of a gelati
Cellular_processes Death Necrosis