phagocytosis

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phagocytosis:

see endocytosisendocytosis
, in biology, process by which substances are taken into the cell. When the cell membrane comes into contact with a suitable food, a portion of the cell cytoplasm surges forward to meet and surround the material and a depression forms within the cell wall.
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Phagocytosis

A mechanism by which single cells of the animal kingdom, such as smaller protozoa, engulf and carry particles into the cytoplasm. It differs from endocytosis primarily in the size of the particle rather than in the mechanism; as particles approach the dimensions and solubility of macromolecules, cells take them up by the process of endocytosis.

Cells such as the free-living amebas or the wandering cells of the metazoa often can “sense” the direction of a potential food source and move toward it (chemotaxis). If, when the cell contacts the particle, the particle has the appropriate chemical composition, or surface charge, it adheres to the cell. The cell responds by forming a hollow, conelike cytoplasmic process around the particle, eventually surrounding it completely. Although the particle is internalized by this sequence of events, it is still enclosed in a portion of the cell's surface membrane and thus isolated from the cell's cytoplasm. The combined particle and membrane package is referred to as a food or phagocytic vacuole. See Vacuole

Ameboid cells of the metazoa also selectively remove foreign particles, bacteria, and other pathogens by phagocytosis. After the foreign particle or microorganism is trapped in a vacuole inside the macrophage, it is usually digested. To accomplish this, small packets (lysosomes) of lytic proenzymes are introduced into the phagocytic vacuole, where the enzymes are then dissolved and activated. See Lysosome

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Phagocytosis

 

the engulfing and absorption of living and nonliving particles by unicellular organisms or specialized cells—phagocytes—in multicellular animals. Phagocytosis was discovered by E. Metchnikoff (I. I. Mechnikov), who traced its evolution and elucidated its function in the defense reactions of the higher animals and man, particularly those related to inflammation and immunity. The process plays a major role in the healing of wounds.

The ability to seize and digest particles, which is the basis of nutrition in primitive organisms, was gradually transferred in the course of evolution to certain specialized cells—initially to the digestive cells and later to some special cells in the connective tissues. In mammals and in man, the neutrophils (that is, micro-phages, or specialized leukocytes) and the reticuloendothelial cells are active phagocytes capable of being transformed into active macrophages. The neutrophils phagocytize small particles, such as bacteria, while macrophages can ingest such larger particles as dead cells and their nuclei and fragments. Marcrophages can also store the negatively charged particles of pigments and of colloidal substances. The ingestion of small colloidal particles is called ultraphagocytosis.

Phagocytosis—a process that requires the expenditure of energy—involves primarily the activity of the cell membrane and intracellular organoids, or lysosomes, which have a high content of hydrolytic enzymes. Phagocytosis proceeds in stages. After a phagocytable particle has attached itself to the cell membrane, an intracellular corpuscle, or phagosome, is formed by invagination of the membrane and the particle. Hydrolytic enzymes enter the phagosome from the surrounding lysosomes and digest the phagocytized particle. Depending on the particle’s physiochemi-cal properties, digestion may be complete or incomplete. In the latter case, a residual corpuscle is formed and may remain in the cell a long time.

REFERENCES

Mechnikov, I. I. Izbrannye biologicheskie proizvedeniia. Moscow, 1950.
Zil’ber, L. A. Osnovy immunologii, 3rd ed. Moscow, 1958.

N. G. KHRUSHCHOV

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

phagocytosis

[‚fag·ə‚sī′tō·səs]
(cell and molecular biology)
A specialized form of macropinocytosis in which cells engulf large solid objects such as bacteria and deliver the internalized objects to special digesting vacuoles; exists in certain cell types, such as macrophages and neutrophils.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
tuberculosis infection begins with the inhalation of airdrops that contain numerous bacilli that are phagocytosed. The initial stages of infection are directed by cells responsible for innate immunity, and the recruitment of inflammatory cells leads to the formation of an early granuloma.
(c) Commensal bacteria and their derivatives (e.g., short-chain fatty acids (SCFAs)) directly stimulate IECs (b) or can be phagocytosed by DCs and macrophages in lamina propria and carried to mesenteric lymph nodes (MLN) where they prime naive B and T cells to mature and differentiate.
So, PMN incubated with CM were cultured with FITC-labelled i-H37Rv, and the percentage of cells that phagocytosed the bacteria ([FITC.sup.+] cells) was measured by FACS.
The phagocytosis function was quantified by measuring the fluorescent intensity of the phagocytosed particles per cell.
Protective immunity to tuberculosis is dependent on the cooperative action of antigen-specific T cells and macrophages, wherein the macrophages ultimately control infection by inhibiting growth of the phagocytosed mycobacteria (15).
Inflammatory cellular response to aspergillosis which was primarily neutrophilic along with large number of moderately lytic neutrophils and bacterial phagocytosed due to secondary bacterial infection (De Lorenzi, 2006) were similar to present case except that septate hyphae were fragmented.
[16] Human neutrophil elastase (HNE) is involved in the degradation of bacteria and immune complexes phagocytosed by polymorphonuclear leucocytes.
Chronic granulomatous disease is a rare inherited disorder characterised by inability of phagocytes to generate reactive oxygen species needed for intracellular killing of phagocytosed microorganisms.
morphology; their cell wall stained vividly purple with periodic acid Schiff (PAS) stain (Figure 4) and most of microorganisms were extracellular, either single or more often in groups, with only a few seen to be phagocytosed.
These apoptotic keratinocytes gets phagocytosed by histiocytes or fibroblasts.
Dendritic cells are antigen presenting cells that display the digested fragments of phagocytosed pathogens to other immune cells.
The ability of the mussel's hemocytes to engulf foreign particles, that is, phagocytosis was evaluated by determining phagocytic rate (the percentage of hemocytes that phagocytose particles) and phagocytic index (the average number of particles phagocytosed per hemocyte) according to the method of Carballal et al.