Degeneration

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degeneration

1. Biology the loss of specialization, function, or structure by organisms and their parts, as in the development of vestigial organs
2. Biology
a. impairment or loss of the function and structure of cells or tissues, as by disease or injury, often leading to death (necrosis) of the involved part
b. the resulting condition
3. Electronics negative feedback of a signal
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Degeneration

 

(biology). (1) In morphology, the process of cell or organ destruction; for example, the disappearance of the tail in the tadpole when it is transformed into a frog.

(2) In microbiology, the attenuation of the viability of a culture of unicellular organisms under unfavorable growth conditions.

(3) The concepts of general and specific degeneration were introduced into the theory of evolution by A. N. Severtsov. By general degeneration, or morphophysiological regression, Severtsov meant one of the trends of the evolutionary process, characterized by a reduction of the organs with active functions (organs of locomotion, sense organs, the central nervous system) and the progressive development of organs that are passive but important for the animal’s survival (the sexual system and the passive means of defense, such as integuments and protective coloration). The development of tunicates, cirripeds, and tapeworms proceeded according to the principle of general degeneration. In specific degeneration, organs present in the ancestors are reduced in the process of an organism’s historical development: for example, the extremities in legless lizards and the shell in cephalopods. The cause of the reduction of organs is the absence of the conditions necessary for their development and functioning.

(4) In pathology, the term “degeneration” was introduced by R. Virchow, who admitted the possibility of the “degeneration” of cells. Present-day medicine has established that changes in cells depend on local or general metabolic disturbance, or dystrophy.


Degeneration

 

a change in the structure and/or function of cells and tissues as a result of certain diseases. The term “degeneration” was introduced into the language of general pathology by R. Virchow to designate processes in which the normal components of the cytoplasm are displaced and in which unnecessary or harmful deposits form in the intercellular matter. The deposits include protein-like substances, fatlike substances (in which case the deposition process is called lipoidosis), and calcium salts. In Soviet medical literature these pathological processes, which Virchow called degenerations, are conventionally termed dystrophies.

In some medical disciplines, “degeneration” has a specific meaning. For example, in neuropathology it usually refers to decomposition of the nerve fiber as a result of injury or death of the corresponding neuron.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

degeneration

[di‚jen·ə′rā·shən]
(electronics)
The loss or gain in an amplifier through unintentional negative feedback.
(medicine)
Deterioration of cellular integrity with no sign of response to injury or disease.
General deterioration of a physical, mental, or moral state.
(statistical mechanics)
A phenomenon which occurs in gases at very low temperatures when the molecular heat drops to less than ³⁄₂ the gas constant.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
In this study, the liver of toad venom-treated animals showed vacuolar degeneration, hepatocyte necrosis, severe sinusoidal congestion, and focal areas of hemorrhage in the parenchyma and below Glisson's capsule.
Grade Lesions condition of pancreas - Normal morphology and structure of pancreas + Inflammatory cell infiltration, B cells swelled and occurred vacuolar degeneration; pancreatic acinar cells of some rates occurred vacuolar degeneration, mild interstitial inflammatory cells infiltration; pancreatic ductal revealed mild dilatation + + Pancreatic B cells particles depigmentation, swelling and occurred vacuolar degeneration, mild atrophy of islet; the number of pancreatic B reduced slightly TABLE 5: Comparison of pancreatic lesions of rats in each group.
In the present study, liver from chicks treated with mold-contaminated feed showed liver lesion including severe vacuolar degeneration of hepatocytes, which is consistent with other studies (Banlunara et al., 2005; Dvorska et al., 2007).
Liver specimens obtained from rats fed on processed mucuna bean diet revealed liver infiltrates, vacuolar degeneration, venous congestion and necrosis of liver cells while specimens from rats fed on protein-free diet exhibited fatty liver degeneration that is associated with lack of protein.
The most common acquired muscle disease in people over 50 years of age, inclusion body myositis (IBM) is a distinct type of inflammatory myopathy characterized by slowly progressing, degenerative muscle changes caused by an antigen-driven inflammatory response, as well as vacuolar degeneration and abnormal protein deposits in distal and proximal muscle cells, Dr.
Microscopically, OLP demonstrates vacuolar degeneration, basal cell lysis, and liquefactive degeneration' along with focal hyperkeratosis, a characteristic amorphous eosinophilic band at the basement membrane level, and a dense, band-like subepithelial lymphocytic infiltrate.
Microscopic examination of heart sections of rats treated with isoproterenol revealed extensive and diffuse vacuolar degeneration of the myocardial bundles and leucocytic infiltration.
The heart had multiple, random foci of patchy vacuolar degeneration of the myocytes and random aggregates of lymphocytes, plasma cells and heterophils.
There are 2 principal lesions seen on electron microscopy myofibrillar loss and vacuolar degeneration.[3] Myofibrillar loss is characterized by partial or total loss of myofibrils within the cell, with Z band remnants remaining.
The basement membranes were extensive vacuolar degeneration. Renal tubular epithelial cells were vacuolar and granular degeneration.
Accordingly, with previous publication in which rodents were fed with the same diet [24] tubular damage was expressed in terms of proximal tubules with vacuolar degeneration and loss of the brush border.

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