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Medical Dictionary


metabolize (me-tab′o-liz)
To undergo the chemical changes of metabolism.

metacarpal (met′a-kar′pal)
1. Relating to the metacarpus. 2. Any one of the m. bones. See m. (bones) [I–V], under bone.

metacarpectomy (met′a-kar-pek′to-me)
Excision of one or all of the metacarpals. [metacarpus + G. ektome, excision]

metacarpophalangeal (met′a-kar′po-fa-lan′je-al)
Relating to the metacarpus and the phalanges; denoting the articulations between them.

metacarpus, pl .metacarpi (met′a-kar′pus, -kar′pi)
The five bones of the hand between the carpus and the phalanges. [meta- + G. karpos, wrist]

metacentric (met-a-sen′trik)
Having the centromere about equidistant from the extremities, said of a chromosome. [meta- + G. kentron, circle]

metacercaria, pl .metacercariae (met′a-ser-kar′e-a, -e)
The post-cercarial encysted stage in the life history of a fluke, prior to transfer to the definitive host. Some cercariae attach themselves to grass or other vegetation, form m., and later are ingested by herbivores, as in Fasciola and similar forms; others encyst in muscles of fish, as in Clonorchis, or in crayfish, as in Paragonimus. [meta- + G. kerkos, tail]

metacestode (met-a-ses′tod)
The larval stages of a tapeworm, including the metamorphosis of the oncosphere to the first evidence of sexuality in the adult worm, differentiation of the scolex, and beginning of proglottid formation; it includes the procercoid and plerocercoid stages of pseudophyllid cestodes, and the cysticercus, cysticercoid, coenurus, and hydatid stages of cyclophyllidean cestodes.

metachloral (met-a-klo′ral)
SYN: m-chloral.

metachromasia (met′a-kro-ma′ze-a)
1. The condition in which a cell or tissue component takes on a color different from the dye solution with which it is stained. SYN: metachromatism (2) . 2. A change in the characteristic color of certain basic thiazine dyes, such as toluidine blue, when the dye molecules are bound in proximate array to tissue polyanionic polymers, such as glycosaminoglycans. [meta- + G. chroma, color]

metachromatic (met′a-kro-mat′ik)
Denoting cells or dyes that exhibit metachromasia. SYN: metachromophil, metachromophile.

metachromatism (met-a-kro′ma-tizm)
1. Any color change, whether natural or produced by basic aniline dyes. 2. SYN: metachromasia (1) . [meta- + G. chroma, color]

metachroming (met′a-kro′ming)
The process of mixing a metal mordant with a dye before applying the dye to a tissue or fabric.

metachromophil, metachromophile (met-a-kro′mo-fil, -fil)
SYN: metachromatic. [meta- + G. chroma, color, + philos, fond]

metachronous (me-tak′ro-nus)
Not synchronous; multiple separate occurrences, such as multiple primary cancers developing at intervals. [meta- + G. chronos, time]

metachrosis (met-a-kro′sis)
A change of color, such as occurs in certain animals, e.g., the chameleon, by expansion and contraction of chromatophores. [meta- + G. chrosis, a coloring]

metacone (met′a-kon)
The distobuccal cusp of an upper molar tooth. [meta- + G. konos, cone]

metaconid (met-a-kon′id, -ko′nid)
The mesolingual cusp of a lower molar tooth.

metacontrast (met-a-kon′trast)
Inhibition of the brightness of illumination when an adjacent visual field is illuminated.

metaconule (met-a-kon′ul)
The distal intermediate cusp of an upper molar tooth. [meta- + G. konos, a cone]

metacresol (met-a-kre′sol)
SYN: m-cresol.

metacryptozoite (met′a-krip-to-zo′it)
The exoerythrocytic stage that develops from merozoites formed by the first, or cryptozoite, generation; the cryptozoite and m. generations comprise the primary exoerythrocytic stages of malaria development (prepatent period) prior to infection of red blood cells. [meta- + G. kryptos, hidden, + zoon, animal]

metadysentery (met-a-dis′en-tar-e)
Old term for bacillary dysentery.

Metagonimus (met-a-gon′i-mus)
A genus of flukes (superfamily Heterophyundea) that encyst on fish and infect various fish-eating animals, including humans. M. yokogawai, an intestinal fluke widely distributed in the Far East and the Balkans and one of the smallest (1–2.5 mm) flukes infecting humans, is passed from Semisulcospira snails to cyprinoid fish and then to humans and other fish-eating mammals and birds. [meta- + G. gonimos, productive]

metaicteric (met-a-ik′ter-ik)
Occurring as a sequel of jaundice. [meta- + G. ikterikos, jaundiced]

metainfective (met′a-in-fek′tiv)
Occurring subsequent to an infection; denoting specifically a febrile condition sometimes observed during convalescence from an infectious disease.

metakinesis, metakinesia (met′a-ki-ne′sis, -ki-ne′se-a)
Moving apart; the separation of the two chromatids of each chromosome and their movement to opposite poles in the anaphase of mitosis. [meta- + G. kinesis, movement]

metal (M) (met′al)
One of the electropositive elements, either amphoteric or basic, usually characterized by properties such as luster, malleability, ductility, the ability to conduct electricity, and the tendency to lose rather than gain electrons in chemicals. [L. metallum, a mine, a mineral, fr. G. metallon, a mine, pit] alkali m. an alkali of the family Li, Na, K, Rb, Cs, and Fr, all of which have highly ionized hydroxides. SYN: alkali (3) . alkali earth m. alkaline earth elements, under element. Babbitt m. an alloy of antimony, copper, and tin; used occasionally in dentistry. base m., basic m. a m. that is readily oxidized; e.g., iron, copper. colloidal m. a colloidal solution of a m. obtained by passing electric sparks between terminals of the m. in distilled water. SYN: electrosol. d'Arcet m. an alloy of lead, bismuth, and tin; used in dentistry. fusible m. a m. with a low melting point. heavy m. a m. with a high specific gravity, typically larger than 5; E.G., Fe, Co, Cu, Mn, Mo, Zn, V. light m. a m. with a specific gravity of less than 4. noble m. a m. that cannot be oxidized by heat alone, nor readily dissolved by acid; e.g., gold, platinum. SYN: noble element. rare earth m. lanthanides. respiratory m. a m. present in certain respiratory pigments; e.g., iron, manganese, copper, vanadium.

metaldehyde (met-al′de-hid)
A polymer of acetaldehyde. [meta- + aldehyde]

metallic (me-tal′ik)
Relating to, composed of, or resembling metal.

Metal, metallic. [see metal]

metallocyanide (me-tal-o-si′a-nid)
A compound of cyanogen with a metal forming an ionic radical that combines with a basic element to form a salt; e.g., potassium ferricyanide, K3Fe(CN)6.

metalloenzyme (me-tal-o-en′zim)
An enzyme containing a metal (ion) as an integral part of its active structure; e.g., cytochromes (Fe, Cu), aldehyde oxidase (Mo), catechol oxidase (Cu), carbonic anhydrase (Zn).

metalloflavodehydrogenase (me-tal′o-fla′vo-de-hi′dro-jen-as)
A type of oxidizing enzyme, containing one of the flavin nucleotides as coenzyme, plus a metal ion that is also necessary to the action; the metal may be Fe (as in succinate dehydrogenase), Cu (as in urate oxidase), or Mo (as in xanthine oxidase).

metalloflavoenzyme (me-tal′o-fla-vo-en′zim)
An enzyme that contains one of the flavin nucleotides and at least one metal ion as a required part of its active structure.

metalloflavoprotein (me-tal′o-fla′vo-pro-ten)
A protein containing a flavin entity and at least one metal ion.

metalloid (met′a-loyd)
Resembling a metal in at least one amphoteric form; e.g., silicon and germanium as semiconductors. [metal + G. eidos, resemblance]

metallophilia (me-tal′o-fil′e-a)
Affinity for metal salts; e.g., the affinity of the cytoplasm of cells of the reticuloendothelial system for silver carbonate stain and salts of gold and iron. [metallo- + G. philos, fond]

metallophobia (me-tal-o-fo′be-a)
Morbid fear of metal objects. [G. metallon, metal, + phobos, fear]

metalloporphyrin (me-tal-o-por′fi-rin)
A combination of a porphyrin with a metal, e.g., Fe (heme), Mg (as in chlorophyll), Cu (in hemocyanin), Zn.

metalloprotein (me-tal-o-pro′ten)
A protein with a tightly bound metal ion or ions; e.g., hemoglobin.

metalloproteinase (met′a-lo-pro′ten-az)
A family of protein-hydrolyzing endopeptidases that contain zinc ions as part of the active structure. matrix m. a subfamily of endopeptidases that hydrolyze extracellular proteins, especially collagens and elastin. By regulating the integrity and composition of the extracellular matrix, these enzymes play a pivotal role in the control of signals elicited by matrix molecules that regulate cell proliferation, differentiation, and death.

metallothionein (me-tal-o-thi′o-nen)
Any of a group of small proteins, rich in cysteinyl residues, that is synthesized in the liver and kidney in response to the presence of divalent ions (zinc, mercury, cadmium, copper, etc.) and that binds these ions tightly; of importance in ion transport and detoxification; the apoprotein is thionein.

metaluetic (met′a-loo-et′ik)
1. SYN: metasyphilitic (1) . 2. SYN: metasyphilitic (2) . 3. SYN: parasyphilitic. [meta- + L. lues, pestilence]

metamer (met′a-mer)
1. An entity that is similar to, but ultimately differentiable from, another entity. 2. Structural isomer. [meta- + -mer]

metamere (met′a-mer)
One of a series of homologous segments in the body. SEE ALSO: somite. [meta- + G. meros, part]

metameric (met-a-mer′ik)
1. Relating to or showing metamerism, or occurring in a metamere. 2. Referring to a metamer.

metamerism (me-tam′er-izm)
1. A type of anatomic structure exhibiting serially homologous metameres; in primitive forms, such as the annelids, the metameres are almost alike in structure; in vertebrates, specialization in the cephalic region masks the underlying m., which is still clearly evident in serially repeated vertebrae, ribs, intercostal muscles, and spinal nerves, and in young vertebrate embryos. 2. In chemistry, rarely used synonym for structural isomerism.

metamorphopsia (met′a-mor-fop′se-a)
Distortion of visual images. [meta- + G. morphe, shape, + opsis, vision]

metamorphosis (met-a-mor′fo-sis, -mor-fo′sis)
1. A change in form, structure, or function. 2. Transition from one developmental stage to another. SYN: allaxis, transformation (1) . [G. metamorphasos, transformation fr. meta, beyond, over, + morphe, form] complete m. insect development from egg, through successive larval instars, pupa, and adult; the latter is distinct from the first two forms of the insect, permitting specialization of feeding (larval) and reproductive-flying functions (adult); characteristic of the higher insect orders, such as Coleoptera (beetles), Hymenoptera (bees, wasps, ants), Diptera (two-winged flies), and Siphonaptera (fleas). SYN: holometabolous m.. fatty m. the appearance of microscopically visible droplets of fat in the cytoplasm of cells. SEE ALSO: fatty degeneration. SYN: fatty change. heterometabolous m. SYN: incomplete m.. holometabolous m. SYN: complete m.. incomplete m. the development of a nymph into the imago which in many respects resembles the former; characteristic of more primitive insect orders, such as Heteroptera (true bugs), Orthoptera (locusts, grasshoppers), and Blatterria (roaches). SYN: heterometabolous m.. retrograde m. SYN: degeneration (3) . 1. SYN: cataplasia.

metamorphotic (met′a-mor-fot′ik)
Relating to or marked by metamorphosis.

metamyelocyte (met-a-mi′el-o-sit)
A transitional form of myelocyte with nuclear construction that is intermediate between the mature myelocyte (myelocyte C of Sabin) and the two-lobed granular leukocyte. SYN: juvenile cell. [meta- + G. myelos, marrow, + kytos, cell]

metanephric (met-a-nef′rik)
Of or pertaining to the metanephron.

metanephrine (met-a-nef′rin)
A catabolite of epinephrine found, together with normetanephrine, in the urine and in some tissues, resulting from the action of catechol-O-methyltransferase on epinephrine; has no sympathomimetic actions.

metanephrogenic, metanephrogenous (met′a-nef-ro-jen′ik, -ne-froj′e-nus)
Applied to the more caudal part of the intermediate mesoderm which, under the inductive action of the metanephric diverticulum, has the potency to form metanephric tubules. [meta- + G. nephros, kidney, + -gen, producing]

metanephros, pl .metanephroi (met-a-nef′ros, -roy)
The most caudally located of the three excretory organs appearing in the evolution of the vertebrates (the others being the pronephros and the mesonephros); in mammalian embryos, the m. develops caudal to the mesonephros during its regression, becoming the permanent kidney. SYN: hind kidney. [meta- + G. nephros, kidney]

metaneutrophil, metaneutrophile (met-a-noo′tro-fil, -fil)
Not staining normally with neutral dyes. [meta- + L. neuter, neither, + G. philos, fond]

metanil yellow (met′a-nil) [C.I. 13065]
A monoazo acid dye, C18H14N3O3SNa, used as a cytoplasmic and connective tissue stain.

metaperiodic acid
SYN: periodic acid (1) .

metaphase (met′a-fas)
The stage of mitosis or meiosis in which the chromosomes become aligned on the equatorial plate of the cell separating the centromeres. In mitosis and in the second meiotic division, the centromeres of each chromosome divide and the two daughter centromeres are directed toward opposite poles of the cell; in the first division of meiosis, the centromeres do not divide but the centromeres of each pair of homologous chromosomes become directed toward opposite poles. [meta- + G. phasis, an appearance]

metaphosphoric acid (met′a-fos-for′ik)
SYN: glacial phosphoric acid.

metaphysial, metaphyseal (met-a-fiz′e-al)
Relating to a metaphysis.

metaphysis, pl .metaphyses (me-taf′i-sis, -sez) [TA]
A conical section of bone between the epiphysis and diaphysis of long bones. [meta- + G. physis, growth]

metaphysitis (me-taf′i-si′tis)
Inflammation of the metaphysis.

metaplasia (met-a-pla′ze-a)
Abnormal transformation of an adult, fully differentiated tissue of one kind into a differentiated tissue of another kind; an acquired condition, in contrast to heteroplasia. SYN: metaplasis (2) . [G. metaplasis, transformation] agnogenic myeloid m. SYN: primary myeloid m.. apocrine m. alteration of acinar epithelium of breast tissue to resemble apocrine sweat glands; seen commonly in fibrocystic disease of the breasts. autoparenchymatous m. m. occurring in the parenchymal cells proper to the tissue. Barrett m. SYN: Barrett syndrome. coelomic m. potential of coelomic epithelium to differentiate into several different histologic cell types. intestinal m. the transformation of mucosa, particularly in the stomach, into glandular mucosa resembling that of the intestines, although usually lacking villi. myeloid m. a syndrome characterized by anemia, enlargement of the spleen, nucleated red blood cells and immature granulocytes in the circulating blood, and conspicuous foci of extramedullary hemopoiesis in the spleen and liver; may develop in the course of polycythemia rubra vera; there is a high incidence of development of myeloid leukemia. primary myeloid m. myeloid m. occurring as the primary condition, often in association with myelofibrosis. SYN: agnogenic myeloid m.. secondary myeloid m. myeloid m. occurring in individuals with another disease. SYN: symptomatic myeloid m.. squamous m. the transformation of glandular or mucosal epithelium into stratified squamous epithelium. SYN: epidermalization. squamous m. of amnion SYN: amnion nodosum. symptomatic myeloid m. SYN: secondary myeloid m..

metaplasis (me-tap′la-sis)
1. The stage of completed growth or development of the individual. 2. SYN: metaplasia. [G. a transformation]

metaplastic (met-a-plas′tik)
Pertaining to metaplasia or metaplasis.

metaplexus (met′a-plek′sus)
The choroid plexus in the fourth ventricle of the brain. [meta- + L. plexus, an interweaving]


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