Morphology: Reversible Injury (EM)
- Membrane bleb
- Mitochondrial swelling
- Swelling of ER and detachment of the ribosomes
- Nuclear changes
Morphology: Reversible Injury (LM)
- Cell swelling: hydropic, vacuoles
- Fatty change
Morphology: Irreversible Injury (LM)
- Karyolysis: pale nuclei
- Pyknosis: nuclear shrinkage and basophilia
- Karyorrhexis: fragmentation of pyknotic nuclei
Patterns of Necrosis:
- Coagulative Necrosis: common following ischemia. There is complete denaturation of proteins including the catabolic enzymes. Morphology: preservation of the basic structure of the tissue.
- Gangrenous Necrosis: occurs in ischemic limb. When it is superimposed by infection, it is called “wet gangrene”
- Liquefactive Necrosis: common following infection by bacteria or fungi due to the enzymatic action of neutrophils. Morphology: digestion of all the cell component resulting in amorphous cellular debris. Brain infarction usually result in liquefactive necrosis.
- Caseous Necrosis: is a special form of necrosis that happen with TB. Morphology: granuloma with central necrosis. The necrosis is grossly white, cheesy material.
- Fat Necrosis: happens in fat destruction, common in pancreatitis after the release of lipase from pancreatic acini. The free fatty acids combine with Ca++ and result in “saponification”