necrosis

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necrosis

1. the death of one or more cells in the body, usually within a localized area, as from an interruption of the blood supply to that part
2. death of plant tissue due to disease, frost, etc.

Necrosis

 

the death within the living organism of individual organs or their component tissues or cells.

A necrosis is classified according to the pathological condition that causes it. Thus, frostbite and burns can cause traumatic necrosis; neurotropic necrosis arises with syringomyelia and the nervous form of leprosy; infarcts and gangrene are associated with circulatory, or ischemic, necrosis; caseous necroses occurring in tuberculosis and syphilis are forms of septic necrosis; and fibrinoid necrosis associated with allergic diseases is a type of allergic necrosis.

Necrosis is accompanied by characteristic changes in the cell and in the intercellular substances. The nucleus shrinks and coagulates, a process known as pycnosis, and the cytoplasm breaks up into clumps. The cell eventually lyses, that is, it degenerates and dissolves. The lysis is due to the activation of the lysosomal hydrolytic enzymes, such as ribonuclease, deoxyribonuclease, and acid phosphatase. The activation of the lysosomes occurs as a result of an increase in the permeability of the cell membranes, changes in the osmotic equilibrium, and acidosis—an abnormal increase in the intracellular hydrogen-ion concentration. Fibrinoid changes appear in the connective tissue, and nerve fibers become fragmented and disintegrate into clumps.

The clinical and morphological manifestations and further consequences of necrosis depend on the localization and distribution of the necrosis and on the mechanisms and conditions of origin. The following types of advanced necrotic conditions can develop: dry necrosis, such as Zenker’s degeneration of infected muscles; colliquative, or liquefactive, necrosis, which occurs for example, when a focus of softening arises in the brain in response to cerebral hemorrhage; gangrene; and bed sores. Necrotic tissue tears away; then, either connective tissue grows through it or the necrotic tissue undergoes autolytic or purulent liquefaction. Finally, the necrotic tissue becomes encapsulated and petrified.

The two most serious consequences of necrosis are a loss of function owing to the death of the structural elements of the necrotic tissues or organs and poisoning caused by the actual presence of a necrotic focus and by the inflammation that arises in response to this presence.

V. V. SEROV

necrosis

[nə′krō·səs]
(medicine)
Death of a cell or group of cells as a result of injury, disease, or other pathologic state.
References in periodicals archive ?
Tubular epithelial coagulative necrosis was seen only in 1 (12%) (Fig.
Light photomicrograph of left ventricle of the heart muscle tissue in control group has been shown; as you see, all layers of muscle cells in this section are normal (Fig.1) and we do not see any abnormality in nucleus or cytoplasm (Fig.2).But in test group, tissue organization is so severely overcrowded, nuclei of muscular cells have been polymorphic and the spaces created around the nucleus and cytoplasm are paled (Fig.3); and tissue fibrosis, cell coagulative necrosis and hemorrhage have been observed (Fig.4).In muscular cell of heart nucleus, swelling and degenerative changes are seen as vacualation of cytoplasm and nucleus which are associated with coagulative necrosis; moreover, some necrotic cells are currently being slippery with focal necrosis, and scattered.
A biopsy analysis of the mass revealed fragments of squamous mucosa that exhibited a dense, expansile, pleomorphic lymphoid infiltrate with an angiocentric growth pattern and prominent coagulative necrosis. The infiltrate was diffuse and composed of small, medium-sized, and large atypical lymphocytes with granular chromatin and clear cytoplasm (figure, A).
reported and discussed the features of all four known malignant HAML patients.3 As showed in the paper, coagulative necrosis, expres- sion of CD117, evidence of metastasis were the main characteristics of malignant HAML, and as with other tumors, the larger the tumor the more likely it is malignant.
Microscopic examination showed severe, acute, necrotizing pneumonia and interstitial subacute to chronic pneumonitis with arteritis (mostly associated with lungworms); multiple foci of acute coagulative necrosis in the liver; and mild, multifocal, non-suppurative meningitis.
The intense heat generated by the focused ultrasound causes protein denaturation, irreversible cell damage and coagulative necrosis at specific target locations.
Thermal injury causes instant coagulative necrosis, which rapidly becomes a favourable niche for bacterial colonisation and proliferation.
gondii, indicative of expansive lesion of the central nervous system, are: diffuse congestion and edema of the encephalic parenchyma and coagulative necrosis with varied sizes, in different evolutionary stages and scattered over the white and grey substances [9].