|Medical Dictionary - Dictionary of Medicine and Human Biology|
SYN: microcythemia. [microcyte + G. -osis, condition]
Relating to or characterized by microdactyly.
Smallness or shortness of the fingers or toes. SYN: microdactylia. [micro- + G. dactylos, finger, toe]
A method of studying extracellular fluid composition and response to exogenous agents, utilizing a tiny tubular probe with a dialysis membrane and fluid flow rates of 1–3 μL/min, inserted into tissues.
Dissection of tissues under a microscope or magnifying glass, usually done by teasing the tissues apart by means of needles.
Having small teeth; denoting a skull with a dental index below 41.9. [micro- + G. odous (odont-), tooth]
microdontia, microdontism (mi-kro-don′she-a, -don′tizm)
A condition in which a single tooth, or pairs of teeth, or the whole dentition, may be disproportionately small. [micro- + G. odous, tooth]
A very small dose.
A chronic hemolytic anemia resulting from interaction of the genes for sickle cell anemia and thalassemia. [microcytosis + drepanocytosis]
Increase in partially distopic neurons in the stratum zonale, white matter, hippocampus and cerebellar cortex, producing an indistinct border between cortex and subcortical white matter and a columnar arrangement of cortical neurons; seen in patients with primary generalized epilepsy. [micro- + dys- + G. genesis, production]
An electrode of very fine caliber consisting usually of a fine wire or a glass tube of capillary diameter (10 μm to 1 mm) drawn to a fine point and filled with saline or a metal such as gallium or indium (while melted); used in physiologic experiments to stimulate or to record action currents of extracellular or intracellular origin.
SYN: trace elements, under element.
The evolution of bacteria and other microorganisms through mutations.
A very small fibril having an average diameter of 13 nm; it may be a bundle of still smaller elements, the microfilaments.
The finest filamentous element of the cytoskeleton, having a diameter of about 5 nm and consisting primarily of actin. SEE ALSO: actin filament.
Infection of the blood with microfilariae. M. caused by Wuchereria bancrofti is characterized by sharp nocturnal periodicity, apparently tied to the nocturnal habits of the vector mosquitoes; in geographic areas where mosquitoes are not strictly night-biters (as in parts of Polynesia), the microfilarial periodicity is modified or absent. SEE ALSO: periodic filariasis.
microfilaria, pl .microfilariae (mi′kro-fi-lar′e-a, -e)
Term for embryos of filarial nematodes in the family Onchocercidae. In the past this term has been used as a generic designation ( e.g., M. bancrofti, M. malaya). See Filaria.
1. A photographic film bearing greatly reduced images of printed records. 2. To record on m..
The bacteria and fungi that inhabit an area.
The male element in anisogamy, or conjugation of cells of unequal size; it is the smaller of the two cells and actively motile. [micro- + G. gametes, husband]
The mother cell producing the microgametes, or male elements of sexual reproduction in sporozoan protozoans and fungi. SYN: microgamont.
Conjugation between two young cells, the recent product of sporulation or some other form of reproduction. [micro- + G. gamos, marriage]
Smallness of the stomach. [micro- + G. gaster, stomach]
Abnormal smallness of the chin resulting from the underdevelopment of the mental symphysis. [micro- + G. geneion, chin]
Abnormal smallness of the external genital organs.
Small neuroglial cells, possibly of mesodermal origin, which may become phagocytic, in areas of neural damage or inflammation. SYN: Hortega cells, m. cells, microglial cells. [micro- + G. glia, glue]
A cell, especially an embryonic cell, of the microglia. [micro- + G. glia, glue, + kytos, cell]
Obsolete term for an intracranial neoplasm of microglial cell origin that is structurally similar to lymphoma. [microglia + G. -oma, tumor]
Obsolete term for a condition characterized by the presence of multiple microgliomas.
Presence of microglia in nervous tissue secondary to injury. [microglia + G. -osis, condition]
1. Any serum or urinary globulin of molecular mass below about 40 kd, including especially Bence Jones proteins, under protein. 2. On occasions, a term used to refer to 7S immunoglobins ( e.g., IgG). β-m. a polypeptide of 11,600 Da that forms the light chain of class 1 major histocompatibility antigens and can therefore be detected on all cells bearing these antigens. Free β-m. is found in the blood and urine of patients with certain diseases, including Wilson disease, cadmium poisoning, and renal tubular acidosis. β2-m. the light chain of the histocompatibility class I molecule. This chain is invariant within a given species; found in elevated levels in individuals with Wilson disease and in alcohol-induced liver cirrhosis.
Smallness of the tongue. [micro- + G. glossa, tongue]
micrognathia (mi-kro-na′the-a, mi-krog-nath′e-a)
Abnormal smallness of the jaws, especially of the mandible. [micro- + G. gnathos, jaw] m. with peromelia hypoplasia of the mandible with malformed and missing teeth, birdlike face, and severe deformities of the hands and forearms and sometimes of feet and legs. SYN: Hanhart syndrome.
microgram (μg, γ) (mi′kro-gram)
One-millionth of a gram.
1. An instrument that magnifies the microscopic movements of a diaphragm by means of light interference and records them on a moving photographic film; may be used for recording various pulse curves, sound waves, and any forms of motion that may be communicated through the air to a diaphragm. 2. SYN: photomicrograph. [micro- + G. grapho, to write] electron m. the image produced by the electron beam of an electron microscope, recorded on an electron-sensitive plate or film. light m. a photograph produced by means of a light microscope.
1. Writing with very minute letters, sometimes observed in psychoses and in paralysis agitans. 2. A description of objects seen with a microscope. 3. SYN: photomicrography. [micro- + G. grapho, to write]
Abnormal narrowness of the cerebral convolutions. [micro- + G. gyros, convolution]
Abnormal smallness of the liver. [micro- + G. hepar (hepat-), liver]
Slight differences in structure between essentially identical molecules; E.G., in the saccharide portion of a glycoprotein.
microhm (μΩ) (mi′krom)
One-millionth of an ohm. SYN: micro-ohm.
Combustion, in a furnace, of organic constituents in a tissue section so that the remaining mineral ash can be examined microscopically. SYN: spodography.
An incision made with the aid of a microscope.
An instrument for infusion of very small amounts of fluids or drugs into animals or humans.
Invasion of tissue immediately adjacent to a carcinoma in situ, the earliest stage of malignant neoplastic invasion.
One-millionth of a katal.
Treatment with high frequency radiations of 3,000,000,000 Hz (3000 MHz), at a wavelength of 10 cm. SYN: microwave therapy. [micro- + G. kyma, a wave, + therapeia, treatment]
microliter (μl, μL) (mi′kro-le-ter)
One-millionth of a liter.
A minute calculus, usually multiple, sometimes constituting a coarse sand called gravel. [micro- + G. lithos, stone]
The formation, presence, or discharge of minute concretions, or gravel, e.g., testicular m.. pulmonary alveolar m. microscopic granules of calcium or bone disseminated throughout the lungs.
The science concerned with microscopic objects, of which histology is a branch. [micro- + G. logos, study]
Dissection, teasing, stimulation, etc., under the microscope, of minute structures; e.g., tissue cells or unicellular organisms.
micromanipulator (mi′kro-ma-nip′u-la′ter, -tor)
An instrument used in micromanipulation, whereby microdissection, microinjection, and other maneuvers are performed, usually with the aid of a microscope.
Condition in which the breasts are rudimentary and functionless. [micro- + G. mazos, breast]
Condition of having disproportionately short or small limbs. SEE ALSO: achondroplasia. SYN: nanomelia. [micro- + G. melos, limb]
A blastomere of small size; for example, one of the blastomeres at the animal pole of an amphibian egg. [micro- + G. meros, a part]
A small merozoite.
A stage of metastasis when the secondary tumors are too small to be clinically detected, as in micrometastatic disease.
Denoting or characterized by micrometastasis, as in m. disease.
micrometer (μm) (mi-krom′e-ter)
1. One-millionth of a meter; formerly called micron. 2. A device for measuring various types of objects in an accurate and precise manner; in medicine and biology, the term is usually used with reference to a glass slide or lens that is accurately marked for measuring microscopic forms. [micro- + G. metron, measure] caliper m. a gauge with a calibrated m. screw for the measurement of thin objects such as microscope cover glasses and slides. filar m. an ocular m. with a line moved by a ruled drum such that a movement of the line of 5 μm or less may be made in relation to fixed parallel lines. ocular m. a glass disk that fits in a microscope eyepiece and that has a ruled scale; when calibrated with a slide m., direct measurements of a microscopic object can be made. slide m. a scale made on a microscope slide with lines ruled in divisions, usually, of 0.01 mm; typically used to calibrate an ocular m..
Measurement of objects with some type of micrometer and a microscope.
Prefix formerly used to signify one-trillionth (10−12); now pico-.
micromicrogram (μμg) (mi′kro-mi′kro-gram)
Former term for picogram.
micromicron (μμ) (mi-kro-mi′kron)
Former term for picometer.
SYN: trace elements, under element.
micromolar (μmol/L) (mi-kro-mo′lar)
Denoting a concentration of 10−6 mol/L.
micromole (μmol) (mi′kro-mol)
One-millionth of a mole.
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