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Medical Dictionary


cytogeneticist (si′to-je-net′i-sist)
A specialist in cytogenetics.

cytogenetics (si′to-je-net′iks)
The branch of genetics concerned with the structure and function of the cell, especially the chromosomes.C. arose as a fusion of 19th century cytology and 20th century genetics, which came into being in 1903 with the articulation of the chromosome theory of inheritance. The developing field concerned itself with detailing the behavior of chromosomes and their functional subunits, the genes, during reproduction, and with relating that behavior statistically to characteristics of the resulting cells or animals. Modern molecular c. involves the microscopic study of chromosomes that have been fixed in mitosis and stained with various agents to delineate characteristic bands. DNA probes can be applied to locate specific gene sequences. Karyotyping is the arrangement of photographs of stained chromosomes in a standard format. Cytogenetic techniques are used to test for inborn errors of metabolism and genomic aberrations such as Down syndrome and to determine sex in cases where anatomy is inconclusive.

cytogenic (si-to-jen′ik)
Relating to cytogenesis.

cytogenous (si-toj′e-nus)

cytoglucopenia (si′to-gloo-ko-pe′ne-a)
An intracellular deficiency of glucose. [cyto- + glucose + G. penia, poverty]

cytoid (si′toyd)
Resembling a cell. [cyto- + G. eidos, resemblance]

cytokeratin (si-to-ker-a-tinz)
SYN: keratin.

cytokine (si′to-kin)
Any of numerous hormonelike, low-molecular-weight proteins, secreted by various cell types, that regulate the intensity and duration of immune response and mediate cell-cell communication. See interferon, interleukin, lymphokine, chemokines. See entries under various growth factors. SEE ALSO: interferon, interleukin, lymphokine. [cyto- + G. kinesis, movement] Cytokines are produced by macrophages, B and T lymphocytes, mast cells, endothelial cells, fibroblasts, and stromal cells of the spleen, thymus, and bone marrow. They are involved in mediating immunity and allergy and in regulating the maturation, growth, and responsiveness of particular cell populations, sometimes including the cells that produce them (autocrine activity). A given c. may be produced by more than one type of cell. Some cytokines enhance or inhibit the action of other cytokines. The first cytokines to be identified were named according to their functions (e.g., T cell growth factor), but this nomenclature became awkward because several cytokines can have the same function, and the function of a c. can vary with the circumstances of its elaboration. Later, as the chemical structure of each c. was determined, it was designated an interleukin and assigned a number (e.g., interleukin-2 [IL-2], formerly T cell growth factor). Cytokines have been implicated in the generation and recall of long-term memory and the focusing of attention. Some of the degenerative effects of aging may be due to a progressive loss of regulatory capacity by cytokines. Because cytokines derived from the immune system (immunokines) are cytotoxic, they have been used against certain types of cancer. c. network a group of cytokines which together modulate and regulate key cellular functions.

cytokinesis (si′to-ki-ne′sis)
Changes occurring in the cytoplasm of the cell outside the nucleus during cell division. SYN: cytodieresis. [cyto- + G. kinesis, movement]

cytolemma (si-to-lem′ma)
SYN: cell membrane. [cyto- + G. lemma, husk]

cytolipin (si-to-lip′in)
A glycosphingolipid, specifically a ceramide oligosaccharide; c. H, a lactosylceramide, may display immunological properties under certain conditions; c. K is probably identical with globoside. Cf.:ceramide lactosidase.

cytologic (si-to-loj′ik)
Relating to cytology.

cytologist (si-tol′o-jist)
One who specializes in cytology.

cytology (si-tol′o-je)
The study of the anatomy, physiology, pathology, and chemistry of the cell. SYN: cellular biology, cytobiology. [cyto- + G. logos, study] exfoliative c. the examination, for diagnostic purposes, of cells denuded from a neoplasm (or other type of lesion) and recovered from the sediment of the exudate, secretions, or washings from the tissue ( e.g., sputum, vaginal secretion, gastric washings, urine). SYN: cytopathology (2) .

cytolysin (si-tol′i-sin)
A substance i.e., an antibody that effects partial or complete destruction of an animal cell; may require complement. SEE ALSO: perforin.

cytolysis (si-tol′i-sis)
The dissolution of a cell. [cyto- + G. lysis, loosening]

cytolysosome (si-to-li′so-som)
A variety of secondary lysosome that contains the remnants of mitochondria, ribosomes, or other organelles. SYN: autophagic vacuole.

cytolytic (si-to-lit′ik)
Pertaining to cytolysis; possessing a solvent or destructive action on cells.

cytomatrix (si-to-ma′triks)
SYN: cytoplasmic matrix.

cytomegalic (si-to-meg′a-lik)
Denoting or characterized by markedly enlarged cells. [cyto- + G. megas, big]

Cytomegalovirus (CMV) (si-to-meg′a-lo-vi′rus)
A group of viruses in the family Herpesviridae infecting humans and other animals, many of the viruses having special affinity for salivary glands, and causing enlargement of cells of various organs and development of characteristic inclusions (owl eye) in the cytoplasm or nucleus. Infection of embryo in utero may result in malformation and fetal death. They are all species-specific and include salivary virus, inclusion body rhinitis virus of pigs, and others. SYN: visceral disease virus. [cyto- + G. megas, big]

cytomembrane (si-to-mem′bran)
SYN: cell membrane.

cytomere (si′to-mer)
The structure separating the portions of the contents of a large schizont in the course of schizogony, as in some of the sporozoans undergoing exoerythrocytic asexual division. Cytomeres are caused by complex invaginations of the surface of the schizont, which isolates them; ultimately, cytomeres complete the budding process in the formation of large numbers of merozoites. [cyto- + G. meros, part]

cytometer (si-tom′e-ter)
A standardized, usually ruled glass slide or small glass chamber of known volume, used in counting and measuring cells, especially blood cells. [cyto- + G. metron, measure] image c. apparatus for measuring various qualitative tests, such as antibody density.

cytometry (si-tom′e-tre)
The counting of cells, especially blood cells, using a cytometer or hemocytometer. Feulgen c. a form of c. using Feulgen-stained nuclei to characterize the chromatin pattern and nuclear distribution of DNA of cells. flow c. a method of measuring fluorescence from stained cells that are in suspension and flowing through a narrow orifice, usually in combination with one or two lasers to activate the dyes; used to measure cell size, number, viability, and nucleic acid content with the aid of acridine orange, Kasten fluorescent Feulgen stain, ethidium bromide, trypan blue, and other selected staining reagents. SYN: flow cytophotometry.

cytomicrosome (si-to-mi′kro-som)
See microsome. [cyto- + G. mikros, small, + soma, body]

cytomorphology (si′to-mor-fol′o-je)
The study of the structure of cells.

cytomorphosis (si′to-mor-fo′sis)
Changes that the cell undergoes during the various stages of its existence. SEE ALSO: prosoplasia. [cyto- + G. morphosis, a shaping]

cytopathic (si-to-path′ik)
Pertaining to or exhibiting cytopathy.

cytopathogenic (si′to-path-o-jen′ik)
Pertaining to an agent or substance that causes a diseased condition in cells, in contrast to histologic changes; used especially with reference to effects observed in cells in tissue cultures.

cytopathologic, cytopathological (si′to-pa-tho-loj′ik, -loj′i-kal)
1. Denoting cellular changes in disease. 2. Relating to cytopathology.

cytopathologist (si′to-pa-thol′o-jist)
A physician, usually skilled in anatomical pathology, who is specially trained and experienced in cytopathology.

cytopathology (si′to-pa-thol′o-je)
1. The study of disease changes within individual cells or cell types. 2. SYN: exfoliative cytology.

cytopathy (si-top′a-the)
Any disorder of a cell or anomaly of any of its constituents. [cyto- + G. pathos, disease]

cytopempsis (si-to-pemp′sis)
SYN: transcytosis. [cyto- + G. pempis, sending through]

cytopenia (si-to-pe′ne-a)
A reduction, i.e., hypocytosis, or a lack of cellular elements in the circulating blood. [cyto- + G. penia, poverty]

cytophagy (si-tof′a-je)
Devouring of other cells by phagocytes. [cyto- + G. phago, to devour]

cytophanere (si′to-fa-ner)
A radial spine seen in certain cysts of Sarcocystis, as in rabbit and sheep tissue cysts. [cyto- + G. phaneros, visible, evident, open]

cytopharynx (si′to-far′inks)
An organelle in certain flagellates and ciliates that serves as a gullet through which food material passes from the cytostome to the cell interior; food passed is collected in food vacuoles, into which digestive enzymes are secreted.

cytophilic (si-to-fil′ik)
SYN: cytotropic. [cyto- + G. philos, fond]

cytophotometry (si′to-fo-tom′e-tre)
A method of measuring the absorption of monochromatic light by stained microscopic structures ( e.g., chromosomes, nuclei, whole cells) with the aid of a photoelectric cell; also used to measure emitted light from such objects by fluorescence in combination with selected fluorochrome dyes. [cyto- + G. phos, light + metron, measure] flow c. SYN: flow cytometry.

cytophylactic (si′to-fi-lak′tik)
Relating to cytophylaxis.

cytophylaxis (si′to-fi-lak′sis)
Protection of cells against lytic agents. [cyto- + G. phylaxis, a guarding]

cytophyletic (si′to-fi-let′ik)
Relating to the genealogy of a cell. [cyto- + G. phyle, a tribe]

cytopipette (si′to-pi-pet′)
A slightly curved, blunt end pipette usually made of glass and fitted with a rubber bulb to provide gentle negative pressure for the collection of vaginal secretions for cytological examination.

cytoplasm (si′to-plazm)
The substance of a cell, exclusive of the nucleus, which contains various organelles and inclusions within a colloidal protoplasm. SEE ALSO: protoplasm, hyaloplasm, cytosol. [cyto- + G. plasma, thing formed] ground-glass c. uniform finely granular eosinophilic c. seen in hepatocytes in carriers of hepatitis B virus, and also in epidermal cells in keratoacanthoma.

cytoplasmic (si-to-plaz′mik)
Relating to the cytoplasm.

cytoplasmon (si-to-plaz′mon)
The total extranuclear genetic information of a eukaryotic cell excluding that of mitochondria and plastids.

cytoplast (si′to-plast)
The living intact cytoplasm that remains following cell enucleation. [cyto- + G. plastos, formed]

cytopoiesis (si-to-poy-e′sis)
Formation of cells. [cyto- + G. poiesis, a making]

cytopreparation (si′to-prep-a-ra′shun)
Laboratory preparation of a cellular specimen for cytologic examination.

cytopyge (si-to-pi′je)
The anal orifice (cell “anus”) found in certain structurally complex protozoa, such as the rumen-dwelling ciliates of herbivores, through which waste matter is ejected. [cyto- + G. pyge, buttocks]

cytoryctes, cytorrhyctes (si-to-rik′tez)
Obsolete term for inclusion bodies, under body. [cyto- + G. oryktes, a digger]

cytoscreener (si′to-skren′er)
SYN: cytotechnologist.

cytosides (si′to-sidz)
Ceramide disaccharides. See glycosphingolipid.

cytosine (Cyt) (si′to-sen)
a pyrimidine found in nucleic acids. c. arabinoside (CA, AraC) 1. a synthetic nucleoside used as an antimetabolite in the treatment of neoplasms; 2. incorrect term for arabinosylcytosine. c. ribonucleoside SYN: cytidine.

cytosis (si-to′sis)
1. A condition in which there is more than the usual number of cells, as in the c. of spinal fluid in acute leptomeningitis. 2. Frequently used with a prefixed combining form as a means of describing certain features pertaining to cells; e.g., isocytosis, equality in size; polycytosis, abnormal increase in number. [cyto- + G. -osis, condition]

cytoskeleton (si-to-skel′e-ton)
The tonofilaments, keratin, desmin, neurofilaments, or other intermediate filaments serving to act as supportive cytoplasmic elements to stiffen cells or to organize intracellular organelles.

cytosmear (si′to-smer)
SYN: cytologic smear.

cytosol (si′to-sol)
Cytoplasm exclusive of the mitochondria, endoplasmic reticulum, and other membranous components. [cyto- + “sol,” abbrev. of soluble]

cytosolic (si-to-sol′ik)
Relating to or contained in the cytosol.

cytosome (si′to-som)
1. The cell body exclusive of the nucleus. 2. Distinctive granule found in great alveolar (type II) cells of the lung that releases pulmonary surfactant on the alveolar surfaces. SYN: multilamellar body. [cyto- + G. soma, body]

cytostasis (si-tos′ta-sis)
The slowing of movement and accumulation of blood cells, especially polymorphonuclear leukocytes, in the capillaries, as in a region of inflammation; obstruction of a capillary as the result of accumulated leukocytes. [cyto- + G. stasis, standing]

cytostatic (si-to-stat′ik)
Characterized by cytostasis.

cytostome (si′to-stom)
The cell “mouth” of certain complex protozoa, usually with a short gullet or cytopharynx leading food into the organism, where it is collected into food vacuoles, then circulated inside the body, eventually to be excreted through the cytopyge. [cyto- + G. stoma, mouth]

cytotactic (si-to-tak′tik)
Relating to cytotaxis.

cytotaxis, cytotaxia (si-to-tak′sis, -tak′se-a)
The attraction (positive c.) or repulsion (negative c.) of cells for one another. [cyto- + G. taxis, arrangement]

cytotechnologist (si′to-tek-nol′o-jist)
A person with special training in cytopathology who is responsible for screening Pap smears and determining which are negative and which require further review by a pathologist. SEE ALSO: Pap smear, Pap test. SYN: cytoscreener.

cytothesis (si-toth′e-sis)
The repair of injury in a cell; the restoration of cells. [cyto- + G. thesis, a placing]

cytotoxic (si-to-tok′sik)
Detrimental or destructive to cells.

cytotoxicity (si′to-tok-sis′i-te)
The quality or state of being cytotoxic. antibody-dependent cell-mediated c. (ADCC) a form of cell-mediated c. that functions by binding of the FC region of IgG antibodies to Fc receptors on leukocytes. The FAB region of the antibody binds to the target cell. Killing of the target cell may be through various modalities, e.g., perforin, reactive oxygen intermediates, cytokines. lymphocyte-mediated c. the toxic or lytic activity of lymphocytes, which may or may not be mediated by antibodies. Cytotoxic T lymphocytes may cause lysis of cells by production of cytolytic proteins such as perforin. B cells may cause lysis of cells by antibody-complement binding to a target cell. Natural killer cells are cytotoxic without prior sensitization. SEE ALSO: antibody-dependent cell-mediated c..

cytotoxin (si′to-tok′sin)
A specific substance, which may or may not be antibody, that inhibits or prevents the functions of cells, causes destruction of cells, or both. SEE ALSO: perforin. [cyto- + G. toxikon, poison] vero c. a cell c. produced by enterohemorrhagic Escherichia coli that appears to contribute to the occurrence of hemorrhagic colitis and hemolytic uremic syndrome. SYN: Shigalike toxin.

cytotrophoblast (si-to-trof′o-blast)
The inner layer of the trophoblast. SYN: Langhans layer.

cytotropic (si-to-trop′ik)
Having an affinity for cells. SYN: cytophilic.

cytotropism (si-tot′ro-pizm)
1. Affinity for cells. 2. Affinity for specific cells, especially the ability of viruses to localize in and damage specific cells. [cyto- + G. tropos, a turning]

cytozoic (si-to-zo′ik)
Living in a cell; denoting certain parasitic protozoa.

cytozoon (si-to-zo′on)
A protozoan cell or organism. [cyto- + G. zoon, animal]

cyturia (si-too′re-a)
The passage of cells in unusual numbers in the urine. [G. kytos, cell, + ouron, urine]

Friedrich J.F., Czechoslovakian botanist, 1868–1921. See C. solution agar, C.-Dox medium.

Abbreviation for capillary zone electrophoresis.

Vincenz, German surgeon, 1842–1916. See C. suture, C.-Lembert suture.

The isomer of retinaldehyde that can combine with opsin to form rhodopsin; it is formed from 11-trans-retinal by retinal isomerase. SYN: neoretinal b.

Retinol with cis configuration at the 11-position (carotenoid numbering) or 5′-position (retinol numbering) of the side chain; an intermediate in the vision cycle. SYN: neoretinene B.


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