ap·op·to·sis (ăp'əp-tōʹsĭs, ăp'ə-tōʹ-)
Disintegration of cells into membrane-bound particles that are then eliminated by phagocytosis or by shedding.
* * *or programmed cell deathMechanism that allows cells to self-destruct when stimulated by the appropriate trigger.It may be initiated when a cell is no longer needed, when a cell becomes a threat to the organism's health, or for other reasons. The aberrant inhibition or initiation of apoptosis contributes to many disease processes, including cancer. Though embryologists had long been familiar with the process of programmed cell death, not until 1972 was the mechanism's broader significance recognized. Apoptosis is distinguished from necrosis, a form of cell death that results from injury.
* * *▪ cytologyalso called Programmed Cell Death,in biology, a mechanism that allows cells to self-destruct when stimulated by the appropriate trigger. Apoptosis is initiated for various reasons, such as when a cell is no longer needed within the body or when it becomes a threat to the health of the organism. Apoptosis is necessary in embryonic development as well as in the daily maintenance of a mature organism. The aberrant inhibition or initiation of apoptosis contributes to many disease processes, including cancer.Embryologists in the early 20th century were familiar with the process of programmed cell death. They observed that as an embryo develops, many of its cells are sacrificed to create the final form of the organism. Not until 1972, however, did researchers John F.R. Kerr, Andrew H. Wyllie, and Alastair Currie recognize the broader significance of this mechanism. They coined the term apoptosis from the Greek word meaning “falling off,” as leaves do in autumn, to describe this natural, timely death of cells. Apoptosis is distinguished from an alternate form of cell death, called necrosis, that results from injury.Apoptosis is a normal physiological process that offsets cell proliferation. It is a genetically programmed event that can be set in motion by a variety of internal or external stimuli. A signal activates genes in the cell's suicide pathway which encode the proteins that destroy the cell's structural proteins and genetic material. A number of morphological changes occur in the apoptotic cell—e.g., the cell begins to shrivel and pull away from other cells, bubblelike formations appear on its surface, and chromatin (chromosomal DNA and protein) in the cell's nucleus condenses. The cell then either is consumed by other cells or breaks up into smaller pieces that are engulfed by scavenger cells. Cells in virtually all tissues may be sacrificed through apoptosis for the good of the organism. For example, the cells of the uterine wall undergo programmed death in the monthly menstrual cycle.Various phenomena can disturb the regulation of the cell death pathway, causing too many or too few cells to die. Many types of disease result from such disruptions. If, for example, a mutation occurs in a gene that induces apoptosis, such as the tumour-suppressor gene p53, the cell that harbours the gene may fail to respond to the cue to die. As a result the cell may proliferate uncontrollably and form a cancerous tumour. In other cases a virus may interfere with the regulation of apoptosis, inducing healthy cells to die. This mechanism is believed to play a role in AIDS, the disease in which infection with the HIV virus results in the destruction of healthy white blood cells called T lymphocytes.
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Apoptosis — (IPA en|ˌæpəpˈtoʊsəs [ [http://www.webster.com/dictionary/apoptosis Webster.com dictionary entry] ] ) is a form of programmed cell death in multicellular organisms. It is one of the main types of programmed cell death (PCD) and involves a series… … Wikipedia
Apoptosis — apoptosis. f. Biol. Modalidad específica de muerte celular, implicada en el control del desarrollo y el crecimiento. * * * La muerte celular programada o apoptosis es el conjunto de reacciones bioquímicas que ocurren en las células cuando se… … Enciclopedia Universal
apoptosis — f. citol. Mecanismo mediante el cual, a partir de una serie de procesos moleculares, la célula muere. Este proceso permite eliminar las células del cuerpo cuando no son necesarias o cuando son defectuosas. Este proceso de suicidio celular no es… … Diccionario médico
apoptosis — apoptosis. См. апоптоз. (Источник: «Англо русский толковый словарь генетических терминов». Арефьев В.А., Лисовенко Л.А., Москва: Изд во ВНИРО, 1995 г.) … Молекулярная биология и генетика. Толковый словарь.
apoptosis — f. Biol. Modalidad específica de muerte celular, implicada en el control del desarrollo y el crecimiento … Diccionario de la lengua española
Apoptosis — La apoptosis es una forma de muerte celular, que está regulada genéticamente. La muerte celular programada es parte integral del desarrollo de los tejidos tanto de plantas como de animales pluricelulares (metazoa). En animales, la forma de muerte … Wikipedia Español
Apoptosis — A form of cell death in which a programmed sequence of events leads to the elimination of cells without releasing harmful substances into the surrounding area. Apoptosis is also called programmed cell death or cell suicide. Apoptosis plays a… … Medical dictionary
apoptosis — n. programmed cell death, which results in the ordered removal of cells and occurs naturally as part of the normal development, maintenance, and renewal of cells, tissues, and organs. During embryonic development, for example, the fingers are… … The new mediacal dictionary
apoptosis — (ap o to sis) Programmed cell death. The fragmentation of a cell into membrane bound particles that are eliminated by phagocytosis. Apoptosis is a physiological suicide mechanism that preserves homeostasis and occurs during normal tissue turnover … Dictionary of microbiology
apoptosis — The most common form of physiological (as opposed to pathological) cell death. Apoptosis is an active process requiring metabolic activity by the dying cell; often characterized by shrinkage of the cell, cleavage of the DNA into fragments that… … Dictionary of molecular biology