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Medical Dictionary - Dictionary of Medicine and Human Biology


Medical Dictionary


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micromotoscope (mi′kro-mo′to-skop)
A cinematoscope for representing the movements of amebas and other motile microscopic objects. [micro- + L. motus, motion, + G. skopeo, to view]

micromyelia (mi′kro-mi-e′le-a)
Abnormal smallness or shortness of the spinal cord. [micro- + G. myelos, marrow]

micromyeloblast (mi-kro-mi′el-o-blast)
A small myeloblast, often the predominating cell in myeloblastic leukemia. SYN: microleukoblast.

micron (μ) (mi′kron)
Former term for micrometer.

microneedle (mi′kro-ne′dl)
A small glass needle used in micrurgical manipulation.

microneme (mi′kro-nem)
A small, osmiophilic, cordlike twisted organelle found in the anterior region of many sporozoans; one of the characteristics that helps to define the subphylum Apicomplexa. SYN: sarconeme. [micro- + G. nema, thread]

micronic (mi-kron′ik)
Of the size of 1 micron (micrometer).

micronodular (mi′kro-nod′u-lar)
Characterized by the presence of minute nodules; denoting a somewhat coarser appearance than that of a granular tissue or substance. [G. mikros, small]

micronucleus (mi-kro-noo′kle-us)
1. A small nucleus in a large cell, or the smaller nuclei in cells that have two or more such structures. 2. The smaller of the two nuclei in ciliates dividing mitotically and bearing specific inheritable material. SYN: gametic nucleus, germ nucleus, gonad nucleus, karyogonad, reproductive nucleus. SEE ALSO: macronucleus (2) .

micronutrients (mi-kro-noo′tre-ents)
Essential food factors required in only small quantities by the body; e.g., vitamins, trace minerals. SYN: trace nutrient.

micronychia (mi-kro-nik′e-a)
Abnormal smallness of nails. [micro- + G. onyx, nail]

micronystagmus (mi′kro-nis-tag′mus)
Nystagmus of so small an amplitude that it is not detected by the usual clinical tests. SYN: minimal amplitude nystagmus. [micro- + G. nystagmos, a nodding]

micro-ohm (mi′kro-om)
SYN: microhm.

microorganism (mi′kro-or′gan-izm)
A microscopic organism (plant or animal).

microparasite (mi-kro-par′a-sit)
A parasitic microorganism.

micropathology (mi′kro-pa-thol′o-je)
Obsolete term for the microscopic study of disease changes. [micro- + G. pathos, suffering, + logos, study]

micropenis (mi-kro-pe′nis)
Abnormally small penis. SYN: microphallus.

microphage (mi′kro-faj)
A polymorphonuclear leukocyte that is phagocytic. SEE ALSO: phagocyte. SYN: microphagocyte. [micro- + phag(ocyte)]

microphagocyte (mi-kro-faj′o-sit)
SYN: microphage.

microphallus (mi-kro-fal′us)
SYN: micropenis.

microphobia (mi-kro-fo′be-a)
Fear of minute objects, microorganisms, germs, etc. [micro- + G. phobos, fear]

microphone (mi′kro-fon)
An instrument for converting sounds to electrical impulses. [micro- + G. phone, sound]

microphonia, microphony (mi-kro-fo′ne-a, mi-krof′o-ne)
SYN: hypophonia. [micro- + G. phone, voice]

microphonoscope (mi-kro-fo′no-skop)
A stethoscope with a diaphragm attachment for magnifying the sound.

microphotograph (mi-kro-fo′to-graf)
A minute photograph of any object, as distinguished from a photomicrograph.

microphthalmia (mi′krof-thal′me-a)
SYN: microphthalmos. colobomatous m. a congenital defect occurring along an embryonic fissure in a small eye, sometimes associated with cysts.

microphthalmos (-thal′mos)
Abnormal smallness of the eye. SYN: microphthalmia, nanophthalmia, nanophthalmos. [micro + G. ophthalmos, eye]

micropipette, micropipet (mi′kro-pi-pet′, -pi-pet′)
A pipette designed for the measurement of very small volumes.

microplania (mi-kro-pla′ne-a)
Decreased horizontal diameter of erythrocytes. [micro- + L. planus, flat]

microplasia (mi-kro-pla′ze-a)
Stunted growth, as in dwarfism. [micro- + G. plasis, a shaping, forming]

microplethysmography (mi′kro-pleth-iz-mog′ra-fe)
The technique of measuring minute changes in the volume of a part as a result of blood flow into or out of it.

micropodia (mi-kro-po′de-a)
Abnormal smallness of the feet. [micro- + G. pous, foot]

micropore (mi′kro-por)
An organelle formed by the pellicle of all stages of sporozoan protozoa of the subphylum Apicomplexa and also found in developmental stages that may lack the inner pellicle layer; it is composed of two concentric rings (in transverse section), the inner of which corresponds with an invagination of the outer pellicle membrane. Micorpores thus far observed seem to serve as feeding organelles; their role in nonfeeding developmental forms is unknown. [micro- + G. poros, pore]

micropromyelocyte (mi′kro-pro-mi′el-o-sit)
A cell derived from a promyelocyte.

microprosopia (mi′kro-pro-so′pe-a)
A condition characterized by an abnormally small or imperfectly developed face. [micro- + G. prosopon, face]

micropsia (mi-krop′se-a)
Perception of objects as smaller than they are. [micro- + G. opsis, sight]

micropuncture (mi′kro-punk-choor)
A small puncture made with the aid of a microscope.

micropyle (mi′kro-pil)
1. Minute opening believed to exist in the investing membrane of certain ova as a point of entrance for the spermatozoon. 2. Former name for micropore. [micro- + G. pyle, gate]

microradiography (mi′kro-ra-de-og′ra-fe)
Making radiographs of histologic sections of tissue for enlargement. SEE ALSO: historadiography.

microrefractometer (mi′kro-re-frak-tom′e-ter)
A refractometer used in the study of blood cells.

microrespirometer (mi′kro-res-pi-rom′e-ter)
An apparatus for measuring the utilization of oxygen by small particles of isolated tissues or cells or particles of cells.

microsaccades (mi′kro-sa-kadz′)
Minute to-and-fro movements of the eyes. [micro- + Fr. saccade, sudden check (of a horse)]

microscintigraphy (mi′kro-sin-tig′ra-fe)
Imaging of small anatomic structures by use of a radionuclide in conjunction with a special collimator which “magnifies” the image; for example, the use of technetium-99m in conjunction with a pinhole collimator to image the lacrimal drainage. [micro- + scintigraphy]

microscope (mi′kro-skop)
An instrument that gives an enlarged image of an object or substance that is minute or not visible with the naked eye; usually the term denotes a compound m.; for low magnifications, the term simple m., or magnifying glass, is used. [micro- + G. skopeo, to view] binocular m. a m. having two eyepieces; it may be a compound m. or a stereoscopic m.. color-contrast m. a type of m. in which the condenser stop is of one color and the annulus is a complement of it so that unstained objects are observed in one color on a field of the other. comparator m. a device constructed with one or more microscopes having micrometer eyepieces used to measure dimensional changes during setting or temperature changes. compound m. a m. having two or more magnifying lenses. confocal m. a m. that allows the observer to visualize objects in a single plane of focus, thereby creating a sharper image (usually the objects are fluorescent molecules); a refinement of this m. uses optical sectioning and a computer to record serial sections. This permits three-dimensional reconstruction. dark-field m. a m. that has a special condenser and objective with a diaphragm or stop that scatters light from the object observed, with the result that the object appears bright on a dark background. electron m. a visual and photographic m. in which electron beams with wavelengths thousands of times shorter than visible light are utilized in place of light, thereby allowing much greater resolution and magnification; in this technique, the electrons are transmitted through a very thin section of an embedded and dehydrated specimen maintained in a vacuum. fluorescence m. fluorescence microscopy. flying spot m. a m. in which a moving spot of light is imaged in the object plane, the energy transmitted by the specimen being detected with a photoelectric cell; the light source may be a cathode ray tube, a scanning disk or drum, or an oscillating mirror. infrared m. a m. that is equipped with infrared transmitting optics and that measures the infrared absorption of minute samples with the aid of photoelectric cells; images may be observed with image converters or television. interference m. a specially constructed m. in which the entering light is split into two beams which pass through the specimen and are recombined in the image plane where the interference effects make the transparent (invisible) refractile object details become visible as intensity differences; permits measurements of light retardation, index of refraction, and thickness and mass of specimen; it is useful in the examination of living or unstained cells. laser m. a m. in which a laser beam is focused on a microscopic field, causing it to vaporize; the emitted radiation is analyzed by means of a microspectrophotometer; at a low intensity the laser is employed as the light source in an interference m.. light m. a class of m. that forms a magnified image using visible light. opaque m. SYN: epimicroscope. operating m. SYN: surgical m.. phase m., phase-contrast m. a specially constructed m. that has a special condenser and objective containing a phase-shifting ring whereby small differences in index of refraction are made visible as intensity or contrast differences in the image; particularly useful for examining structural details in transparent specimens such as living or unstained cells and tissues. polarizing m. a m. equipped with a polarizing filter below and above the specimen which forms an image by the influence of specimen birefringence on polarized light; the polarizing direction of the two filters is typically adjustable which, together with a graduated rotating stage, permits measurement of the angular value of different refractive indices in either biological or chemical specimens. Rheinberg m. a modified form of dark-field m. in which the central opaque stop in the condenser is replaced by a colored filter, producing a background of contrasting color against which the specimen is illuminated. scanning electron m. a m. in which the object in a vacuum is scanned in a raster pattern by a slender electron beam, generating reflected and secondary electrons from the specimen surface that are used to modulate the image on a synchronously scanned cathode ray tube; with this method a three-dimensional image is obtained, with both high resolution and great depth of focus. simple m., single m. a m. that has a single magnifying lens. stereoscopic m. a m. having double eyepieces and objectives and thus independent light paths, giving a three-dimensional image. stroboscopic m. a m. that has a light source that flashes at a constant rate so that an analysis of the motility of an object may be made; it may be used for high speed or low speed (time-lapse) cinephotomicrography. surgical m. a binocular m. used to obtain good visualization of fine structures in the operating field; in the standing type of m., a motorized zoom lens system operated by hand or foot controls provides an adjustable working distance; in headborne models, interchangeable oculars provide the magnification needed. SYN: operating m.. television m. a m. in which the image is observed by a television camera that produces a television display; it is used for quantitative studies, display to a large audience, or examinations in ultraviolet and infrared regions of the spectrum. ultra-m. ultramicroscope. ultrasonic m. a m. that has lenses designed to use acoustic energy so that the ultrasonic wavelengths may be utilized; by means of transducers, the information is translated to a form that may be visualized or recorded. ultraviolet m. a m. having optics of quartz and fluorite that allow transmission of light waves shorter than those of the visible spectrum, i.e., below 400 nm; the image is made visible by photography, fluorescence of special glasses, or television; in a scanning instrument the receptor is a multiplier phototube. x-ray m. a m. in which images are obtained by using x-rays as an energy source that are recorded on a very fine-grained film, or the image is enlarged by projection; if film is used, it may be examined with the light m. at fairly high magnifications.

microscopic, microscopical (mi-kro-skop′ik, -i-kal)
1. Of minute size; visible only with the aid of the microscope. 2. Relating to a microscope.

microscopy (mi-kros′ko-pe)
Investigation of minute objects by means of a microscope. SEE ALSO: microscope. electron m. examination of minute objects by use of an electron microscope. epiluminescence m. low-power m. (×50–×100), commonly a television microscope applied to a glass slide covering mineral oil on the surface of a skin lesion, e.g., to determine malignancy in pigmented lesions. SYN: surface m.. fluorescence m. a procedure based on the fact that fluorescent materials emit visible light when they are irradiated with ultraviolet or violet-blue visible rays; some materials manifest this property naturally, whereas others may be treated with fluorescent solutions (somewhat analogous to staining); when the absorption of the specimen is in the relatively long ultraviolet range, a filter that transmits these radiations is used, and a yellow filter is placed on or in the ocular; the background field is then dark, and any yellow or red fluorescence becomes visible. immersion m. immersion. immune electron m. electron m. of biological specimens to which specific antibody has been bound. immunofluorescence m. immunofluorescence. Nomarski interference m. Nomarski optics. surface m. SYN: epiluminescence m.. time-lapse m. m. in which the same object ( E.G., a cell) is photographed at regular time intervals over several hours.

microseme (mi′kro-sem)
Denoting a skull with an orbital index below 84. [micro- + G. sema, sign]

microsides (mi′kro-sidz)
Fatty acid esters of trehalose and mannose isolated from diphtheria bacilli.

microsmatic (mi′kroz-mat′ik)
Having a weakly developed sense of smell. [micro- + G. osme, sense of smell]

microsome (mi′kro-som)
One of the small spherical vesicles derived from the endoplasmic reticulum after disruption of cells and ultracentrifugation. [micro- + G. soma, body]

microsomia (mi-kro-so′me-a)
Abnormal smallness of body, as in dwarfism or as in a fetus. SYN: nanocormia. [micro- + G. soma, body]

microspectrophotometry (mi′kro-spek-tro-fo-tom′e-tre)
A technique for characterizing and quantitating nucleoproteins in single cells or cell organelles by their natural absorption spectra (ultraviolet) or after binding stoichiometrically in selective cytochemical staining reactions, as in the Feulgen stain for DNA. SEE ALSO: cytophotometry.

microspectroscope (mi-kro-spek′tro-skop)
An instrument for observing the optical spectrum of microscopic objects.

microsphere (mi′kro-sfer)
Tiny globules of radiolabeled material such as macroaggregated albumin, about 15 microns in size.

microspherocytosis (mi′kro-sfer′o-si-to′sis)
SYN: spherocytosis.

microsphygmy (mi′kro-sfig′me)
Smallness of the pulse. SYN: microsphyxia. [micro- + G. sphygmos, pulse]

microsphyxia (mi-kro-sfik′se-a)
SYN: microsphygmy. [micro- + G. sphyxis, pulse]

microsplanchnic (mi-kro-splangk′nik)
Referring to smallness of the abdominal viscera. [micro- + G. splanchna, viscera]

microsplenia (mi-kro-sple′ne-a)
Abnormal smallness of the spleen.

Microspora (mi-kro-spor′a)
A protozoan phylum that includes the genus Nosema and Encephalitozoon, and is characterized by the presence of unicellular spores with an imperforate wall and an extrusion apparatus having a polar tube and a polar cap; mitochondria are absent. They are intracellular parasites of invertebrates and lower vertebrates, with rare examples in higher vertebrates. SYN: Cnidospora. [micro- + G. sporos, seed]

Microsporasida (mi′kro-spor-as′i-da)
SYN: Microsporida.

Microsporida (mi-kro-spo′ri-da)
An order of the protozoan class Microsporea and phylum Microspora, characterized by minute spores with a single long, coiled, tubular filament enclosing the infective cell or sporoplasm. They are typically parasites of invertebrates and lower vertebrates, although fish and higher vertebrates (including man) have been infected. The order includes genera such as Encephalitozoon and Nosema. SYN: Cnidosporidia, Microsporasida.

microsporidia (mi′kro-spor-id′e-a)
Common name for members of the protozoan phylum Microspora. It includes some 80 genera parasitizing all classes of vertebrates and many invertebrates, especially the insects. Several genera, such as Encephalitozoon, Enterocytozoon, Nosema, Vittaforma, Pleistophora, and Trachipleistophora have been implicated in the infection of immunocompromised humans.

microsporidiasis (mi′kro-spo-ri-di′a-sis)
See microsporidiosis.

microsporidiosis, microsporidiasis (mi-kro-spo-rid-e-o′sis, mi′kro-spo-ri-di′a-sis)
Infection with a member of the phylum Microspora, the microsporidians.

Microsporum (mi-kros′po-rum, mi-kro-spo′rum)
A genus of pathogenic fungi causing dermatophytosis. In appropriate culture media, characteristic macroconidia are seen; microconidia are rare in most species. [micro- + G. sporos, seed] M. audouinii an anthrophilic fungal species of fungi that has caused epidemic tinea capitis in children. M. canis the principal cause of ringworm in dogs and cats and a zoophilic fungal species of fungi causing sporadic dermatophytosis in humans, especially tinea capitis in children with cats and dogs. M. canis, var. distortum a zoophilic fungal species that causes dermatophytosis in humans and animals; seen among laboratory animal handlers. M. ferrugineum an anthropophilic fungal species that causes dermatophytosis, primarily in Japan and the Far East. M. fulvum a geophilic fungal species that causes dermatophytosis in humans and is a member of the M. gypseum complex whose ascomycetous state elevates it to the rank of a specific species. M. gallinae a fungal species that causes dermatophytosis in fowl and, occasionally, in humans; due to its broadly clavate macroconidia, it was erroneously classified as a species of Trichophyton. M. gypseum a cause of ringworm in dogs and horses and occasionally other animal species; a geophilic complex of fungal species causing sporadic dermatophytosis in humans. M. nanum a geophilic fungal species that is the principal cause of ringworm in pigs; rarely causes dermatophytosis in humans. M. persicolor a geophilic fungal species that causes dermatophytosis in voles, field voles, and, occasionally, humans; its ascomycetous state is Nannizzia persicolor. M. vanbreuseghemi a zoophilic fungal species that causes dermatophytosis in dogs and squirrels, and occasionally in humans.

microstethophone (mi-kro-steth′o-fon)
SYN: microstethoscope. [micro- + G. stethos, chest, + phone, sound]




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