Tissue necrosis

Introduction After local tissue and cell metabolism stop, its function is completely lost. The cells may undergo changes such as nuclear condensation, nuclear fragmentation, and nuclear dissolution. The death of local tissues and cells in vivo is called necrosis of local tissues in vivo, and the death of cells is called necrosis. Necrosis is the death of local tissue cells in vivo characterized by changes in enzyme solubility. Necrosis can be directly caused by strong pathogenic factors, but most of them are developed from reversible damage. The basic manifestations are cell swelling, organelle disintegration and protein denaturation.

Cause

Any factor that can cause damage (hypoxia, physical factors, chemical factors, biological factors, immune responses, etc.), as long as its effect reaches a certain intensity or for a certain period of time, the metabolism of damaged tissues and cells can be completely stopped to cause local Tissue and cell death. The metabolism of necrotic tissue cells is stopped and the function is lost. The morphological changes of necrosis may be caused by the degradation of hydrolase in the damaged cells, or by the action of hydrolases released by the leukocytes that have migrated.

an examination

Related inspection

Bacteriological test of mouse virulence test

The organization that truly loses its ability to live is called inactivation tissue. Generally, the inactivated tissue has a dull appearance and is relatively turbid (matte). Loss of normal tissue elasticity (inelasticity). Because of the lack of normal blood supply, the temperature is low, and the pulsation of the blood vessels is not felt. When the inactivated tissue is removed during debridement, no fresh blood flows out from the blood vessels (no blood supply). Inactivated tissue loses normal sensation (skin pain, tenderness) and motor function (intestinal peristalsis) (no sensory and motor function).

Differential diagnosis

Tissue necrosis symptoms need to be identified as follows.

(1) Coagulative necrosis: necrotic tissue becomes dry gray and yellowish white due to dehydration and protein solidification, and is a relatively dry and solidified solidified body, which is common in ischemic necrosis-infarction of organs such as heart, kidney and spleen. The boundary between necrotic foci and healthy tissue is obvious. The outline of the tissue structure can be seen under the light microscope.

(2) liquefaction necrosis: Some tissues are decomposed into liquid state by necrosis, and can form necrotic sac, mainly in tissues containing less protein and lipids (such as brain) or producing more proteases (such as pancreas). The liquefaction necrosis that occurs in brain tissue is also called brain softening.

(3) Cellulose-like necrosis: a type of necrosis that occurs in the interstitial, collagen fibers, and small vessel walls. Under the light microscope, the tissue structure of the lesion disappeared, and it became a granular, small or small block-like structure with a clear boundary. It was strongly eosinophilic, like fibrin, and sometimes fibrin staining was positive. Common in acute rheumatism, systemic lupus erythematosus, glomerulonephritis and other allergic diseases.

(4) Gangrene: After tissue necrosis, special morphological changes such as black and dark green are observed due to the infection of secondary spoilage bacteria and other factors.

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