What is Avascular Necrosis?

Necrosis is the death of local tissue cells in the living body characterized by changes in enzyme solubility. Necrosis can be directly caused by strong pathogenic factors, but most of them develop from reversible damage, and their basic manifestations are cell swelling, organelle disintegration and protein degeneration. During inflammation, lysosomal enzymes are released from necrotic cells and neutrophils exuding from surrounding cells. Can promote the further occurrence of necrosis and local parenchymal cell lysis, so necrosis often involves multiple cells at the same time. ^[1-2]

Necrosis is the death of local tissue cells in the living body characterized by changes in enzyme solubility. Necrosis can be directly caused by strong pathogenic factors, but most of them develop from reversible damage, and their basic manifestations are cell swelling, organelle disintegration and protein degeneration. Necrotic cells and surrounding exudates during inflammation

The death of local tissue cells in vivo, characterized by changes in enzyme solubility, becomes necrosis. ^[1]

Due to the different role of enzyme degradation or protein denaturation, different morphological changes in necrotic tissues are usually divided into three basic types: coagulation necrosis, liquefaction necrosis and cellulose-like necrosis. In addition, there are some special types of necrosis such as caseous necrosis, fat necrosis and gangrene. Tissue necrosis is pale in color, loses the elasticity of normal tissues, loses normal sensation (skin pain, tenderness) and motor function, and has no pulsation of blood. When inactivating tissue is removed during debridement, no fresh blood flows out of the blood vessels. This type of tissue is called inactivated tissue and should be removed in time.

Necrotic cells and peripherally exuding neutrophils release lysosomal enzymes. It can promote the further occurrence of necrosis and local parenchymal cell lysis, so necrosis often involves multiple cells at the same time, and causes inflammation of the tissue, which in turn causes more serious consequences. ^[1]

Difference	Necrosis	Apoptosis
cause	Pathological changes or severe injuries	Physiological or pathological
range	Large tracts of tissue or clusters of cells	Single scattered cell
Cell membrane	damaged	Remain intact until apoptotic bodies are formed
Chromatin	Flocculent	Condensed under the nuclear membrane,
Organelle	Swelling, disintegration of the endoplasmic reticulum	No significant changes
Cell volume	Swelling becomes larger	Shrinkage
Apoptotic body	None, cells are autolysed, residual debris is engulfed by macrophages	Yes, swallowed by neighboring cells or macrophages
Genomic DNA	Randomly degraded, smeared electrophoresis	Controlled degradation with ladder-like bands
Protein synthesis	no	Have
Regulation process	Passive	Regulated by genes
Inflammation	Yes, release contents	None, does not release cell contents

Note: Source of form reference ^{[3] [5-6]}