Cellular Injury IV: Necrosis

Necrosis is a form of cell death caused by severe injury, such as ischemia, bacterial toxins, or trauma.

It begins with damage that causes swelling inside the cell and a drop in energy.

As membrane integrity is lost, lysosomal enzymes are released and digest the cell. The nucleus then undergoes a series of changes: chromatin condenses, and the nucleus shrinks, a process called pyknosis, the nuclear material breaks apart, known as karyorrhexis; and finally, the nuclear remnants dissolve completely, referred to as karyolysis.

As the cell ruptures, its contents trigger inflammation, and immune cells arrive to clean up the debris.

Examining its types clarifies how necrosis appears across tissues.

Coagulative necrosis results in firm, pale tissue. Liquefactive necrosis leads to soft, fluid-like areas.

Gangrenous necrosis involves large tissue areas that may become dry, wet, or gas-filled when infected.