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Medical Dictionary


mycose (mi′kos)
SYN: trehalose.

mycosis, pl .mycoses (mi-ko′sis, -sez)
Any disease caused by a fungus (filamentous or yeast). [myco- + G. -osis, condition] m. framboesioides SYN: yaws. m. fungoides a chronic progressive lymphoma arising in the skin that initially simulates eczema or other inflammatory dermatoses; the appearance of plaques is associated with acanthosis and bandlike infiltration of the upper dermis by a pleomorphic infiltrate including helper T lymphocytes with large, convoluted nuclei that also collect in clear spaces in the lower epidermis (Pautrier microabscesses); in advanced cases, ulcerated tumors and infiltration of lymph nodes may occur. m. intestinalis gastroenteric form of anthrax, the symptoms of which are those of gastroenteritis followed by toxemia and general depression.

mycostatic (mi-ko-stat′ik)
SYN: fungistatic.

mycosterols (mi-kos′ter-olz)
Sterols obtained from fungi.

mycotic (mi-kot′ik)
Relating to or caused by a fungus.

mycotoxicosis (mi′ko-tok-si-ko′sis)
Poisoning due to the ingestion of preformed substances produced by the action of certain fungi on particular foodstuffs or ingestion of the fungi themselves; e.g., ergotism. [myco- + G. toxikon, poison, + -osis, condition]

mycotoxin (mi′ko-tok-sinz)
Toxic compound produced by certain fungi; some are used for medicinal purposes; e.g., muscarine, psilocybin.

mycovirus (mi′ko-vi-rus)
A virus that infects fungi.

mydaleine (mi-da′le-en)
A poisonous ptomaine formed in putrefying liver and other viscera; it acts specifically upon the heart, causing arrest of its action in diastole. [G. mydaleos, moldy, fr. mydos, dampness]

mydatoxin (mi-da-tok′sin)
A ptomaine from putrefying viscera and flesh. [G. mydos, dampness, decay, + toxikon, poison]

mydriasis (mi-dri′a-sis)
Dilation of the pupil. [G.] alternating m. m. alternately affecting each eye. amaurotic m. a moderate widening of both pupils resulting from impaired visual input from one or both eyes. paralytic m. pupillary dilation due to paralysis of the sphincter muscle of the pupil induced by anticholinergic drugs given topically or systemically, or resulting from lesions of the oculomotor nucleus or nerve, contusion of the eyeball, or glaucoma. spastic m. pupillary dilation due to contraction of the dilator muscle of the pupil induced by adrenergic drugs or by stimulation of the sympathetic pathway.

mydriatic (mi-dre-at′ik)
1. Causing mydriasis or dilation of the pupil. 2. An agent that dilates the pupil.

myectomy (mi-ek′to-me)
Excision of a portion of a muscle. [G. mys, muscle, + ektome, excision]

myectopy, myectopia (mi-ek′to-pe, mi-ek-to′pe-a)
Rarely used term for dislocation of a muscle. [G. mys, muscle, + ektopos, out of place]

myel-, myelo-
1. The bone marrow. 2. The spinal cord and medulla oblongata. Cf.:medullo-. 3. The myelin sheath of nerve fibers. [G. myelos, medulla, marrow]

myelapoplexy (mi′el-ap′o-plek′se)
SYN: hematomyelia. [myel- + G. apoplexia, apoplexy]

myelatelia (mi′el-a-te′le-a)
Developmental defect of the spinal cord. [myel- + G. ateleia, incompleteness]

myelauxe (mi-el-awk′se)
Hypertrophy of the spinal cord. [myel- + G. auxe, increase]

myelemia (mi-e-le′me-a)
Rarely used term for myelocytosis. [myel- + G. haima, blood]

myelencephalon (mi′el-en-sef′a-lon) [TA]
SYN: medulla oblongata. [myel- + G. enkephalos, brain]

myelic (mi-el′ik)
Relating to (1) the spinal cord, or (2) bone marrow.

myelin (mi′e-lin)
1. The lipoproteinaceous material, composed of regularly alternating membranes of lipid lamellae (cholesterol, phospholipids, sphingolipids, phosphatidates) and protein, of the m. sheath. 2. Droplets of lipid formed during autolysis and postmortem decomposition.

myelinated (mi′e-li-nat-ed)
Having a myelin sheath. SYN: medullated (2) .

myelination (mi′e-li-na′shun)
The acquisition, development, or formation of a myelin sheath around a nerve fiber. SYN: medullation (2) , myelinization, myelinogenesis.

myelinic (mi′e-lin′ik)
Relating to myelin.

myelinization (mi′e-li-ni-za′shun)
SYN: myelination.

myelinoclasis (mi′e-li-nok′la-sis)
Destruction of myelin. SEE ALSO: demyelination, dysmyelination. [myelin + G. klasis, a breaking]

myelinogenesis (mi′e-lin-o-jen′e-sis)
SYN: myelination. [myelin + G. genesis, production]

myelinolysis (mi′e-li-nol′i-sis)
Dissolution of the myelin sheaths of nerve fibers. [myelin + G. lysis, dissolution] central pontine m. localized loss of myelin within the midbase of the pons; related to malnutrition and often to alcoholism.

myelinopathy (mi′e-lin-op′a-the)
A disorder affecting the myelin of peripheral nerve fibers, in contrast to one affecting axons (axonopathy).

myelitic (mi-e-lit′ik)
Relating to or affected by myelitis.

myelitis (mi-e-li′tis)
1. Inflammation of the spinal cord. 2. Inflammation of the bone marrow. [myel- + G. -itis, inflammation] acute necrotizing m. a spinal cord disorder, probably a demyelinating disease, which affects persons of all ages and either sex. Presents with abrupt or more gradual onset with sensory abnormalities and upper motor neuron weakness; soon a reflexic flaccid motor paralysis and sphincter paralysis supervenes, which is permanent. In some, but not all cases, bilateral or unilateral optic neuritis is associated. In the cerebrospinal fluid, the protein is increased, and mononuclear cells are present. After autopsy, the lesion has been identified as a necrotizing hemorrhagic leukomyelitis. acute transverse m. acute inflammation and softening of the spinal cord; involves the entire thickness of the spinal cord but of limited longitudinal extent; multiple etiologies. ascending m. progressive inflammation involving successively higher areas of the spinal cord. bulbar m. inflammation of the medulla oblongata. concussion m. traumatic myelopathy. demyelinated m. acute multiple sclerosis presenting as a m.. Foix-Alajouanine m. SYN: subacute necrotizing m.. funicular m. 1. inflammation involving any of the columns of the spinal cord; 2. SYN: subacute combined degeneration of the spinal cord. postinfectious m. spinal cord inflammation that follows a viral infection, usually one of the exanthemas. postvaccinal m. spinal cord inflammation that follows vaccination. radiation m. SYN: radiation myelopathy. subacute necrotizing m. a disorder of the lower spinal cord in adult males resulting in progressive paraplegia. SYN: angiodysgenetic myelomalacia, Foix-Alajouanine m.. systemic m. inflammation confined to special tracts of the spinal cord. transverse m. an inflammatory process involving both gray and white matter of spinal cord.

See myel-.

myeloarchitectonics (mi′e-lo-ar′ki-tek-ton′iks)
The pattern of myelinated nerve fibers in the brain, as distinguished from cytoarchitectonics.

myeloblast (mi′e-lo-blast)
An immature cell (10 to 18 μm in diameter) in the granulocytic series, occurring normally in bone marrow, but not in the circulating blood (except in certain diseases). When stained with the usual dyes, the cytoplasm is light blue, nongranular, and variable in amount, sometimes being only a thin rim around the nucleus; the latter is deep purple-blue with finely divided, punctate, threadlike chromatin that is somewhat condensed at the periphery. A few light blue nucleoli are usually present in the nucleus, and these generally disappear as the m. matures into a promyelocyte and then a myelocyte. Myeloblasts ordinarily yield a negative reaction with peroxidase. [myelo- + G. blastos, germ]

myeloblastemia (mi′e-lo-blas-te′me-a)
The presence of myeloblasts in the circulating blood. [myeloblast + G. haima, blood]

myeloblastoma (mi′e-lo-blas-to′ma)
A nodular focus or fairly well-circumscribed accumulation of myeloblasts, as sometimes observed in acute myeloblastic leukemia and chlorosis. [myeloblast + G. -oma, tumor]

myeloblastosis (mi′e-lo-blas-to′sis)
The presence of unusually large numbers of myeloblasts in the circulating blood, or tissues, or both (as in acute leukemia).

myelocele (mi′e-lo-sel)
1. Protrusion of the spinal cord in spina bifida. [myelo- + G. kele, hernia] 2. The central canal of the spinal cord. [G. myelos, marrow, + koilia, a hollow]

myelocyst (mi′e-lo-sist)
Any cyst (usually lined with columnar or cuboidal cells) that develops from a rudimentary central canal in the central nervous system. [myelo- + G. kystis, bladder]

myelocystic (mi′e-lo-sist′ik)
Pertaining to or characterized by the presence of a myelocyst.

myelocystocele (mi′e-lo-sis′to-sel)
Spina bifida containing spinal cord substance. [myelo- + G. kystis, bladder, + kele, tumor]

myelocystomeningocele (mi′e-lo-sis′to-me-ning′go-sel)
SYN: meningomyelocele. [myelo- + G. kystis, bladder, + meninx (mening-), membrane, + kele, hernia]

myelocyte (mi′e-lo-sit)
1. A young cell of the granulocytic series, occurring normally in bone marrow, but not in circulating blood (except in certain diseases). When stained with the usual dyes, the cytoplasm is distinctly basophilic and relatively more abundant than in myeloblasts or promyelocytes, even though m.'s are smaller cells; numerous cytoplasmic granules ( i.e., neutrophilic, eosinophilic, or basophilic) are present in the more mature forms of m.'s, and the first two types are peroxidase-positive. The nuclear chromatin is coarser than that observed in myeloblasts, but it is relatively faintly stained and lacks a well defined membrane; the nucleus is fairly regular in contour ( i.e., not indented), and seems to be “buried” beneath the numerous cytoplasmic granules. 2. A nerve cell of the gray matter of the brain or spinal cord. SYN: medullocell. [myelo- + G. kytos, cell] m. A the youngest form of m., characterized by only a few (not more than ten) cytoplasmic granules, which are most reliably demonstrated by means of staining with neutral red; the mitochondria are numerous, and resemble those of the myeloblast. m. B the intermediate form of m., characterized by approximately 30–100 (or more) cytoplasmic granules scattered among the mitochondria; the latter are less numerous than in myelocytes of the A stage, and they are frequently displaced toward the periphery of the cell. m. C the most mature of the myelocytes characterized by numerous cytoplasmic granules that are recognizable as neutrophilic, eosinophilic, and basophilic; with neutral red these are stained, respectively, red, bright yellow, and deep maroon; C myelocytes are frequently larger than earlier forms; if the nucleus is indented, the m. is maturing into a metamyelocyte.

myelocythemia (mi′e-lo-si-the′me-a)
The presence of myelocytes in the circulating blood, especially in persistently large numbers (as in myelocytic leukemia). [myelocyte + G. haima, blood]

myelocytic (mi′e-lo-sit′ik)
Pertaining to or characterized by myelocytes.

myelocytoma (mi′e-lo-si-to′ma)
A nodular focus or fairly well-circumscribed, relatively dense accumulation of myelocytes, as in certain tissues of persons with myelocytic leukemia. [myelocyte + G. -oma, tumor]

myelocytomatosis (mi′e-lo-si′to-ma-to′sis)
A form of tumor involving chiefly the myelocytes.

myelocytosis (mi′e-lo-si-to′sis)
The occurrence of abnormally large numbers of myelocytes in the circulating blood, or tissues, or both. [myelocyte + G. -osis, condition]

myelodiastasis (mi′e-lo-di-as′ta-sis)
Softening and destruction of the spinal cord. [myelo- + G. diastasis, separation]

myelodysplasia (mi′e-lo-dis-pla′ze-a)
1. An abnormality in development of the spinal cord, especially the lower part of the cord. 2. Inappropriate term for spina bifida occulta. [myelo- + G. dys-, difficult, + plasis, a molding]

myelofibrosis (mi′e-lo-fi-bro′sis)
Fibrosis of the bone marrow, especially generalized, associated with myeloid metaplasia of the spleen and other organs, leukoerythroblastic anemia, and thrombocytopenia, although the bone marrow often contains many megakaryocytes. SYN: myelosclerosis, osteomyelofibrotic syndrome.

myelogenesis (mi′e-lo-jen′e-sis)
1. Development of bone marrow. 2. Development of the central nervous system. 3. Formation of myelin around an axon.

myelogenetic, myelogenic (mi′e-lo-je-net′ik, -jen′ik)
1. Relating to myelogenesis. 2. Produced by or originating in the bone marrow. SYN: myelogenous.

myelogenous (mi-e-loj′e-nus)
SYN: myelogenetic (2) .

myelogone, myelogonium (mi′e-lo-gon, mi′e-lo-go′ne-um)
An immature white blood cell of the myeloid series that is characterized by a relatively large, fairly deeply stained, finely reticulated nucleus that contains palely stained nucleoli, and a scant amount of rimlike, nongranular, moderately basophilic cytoplasm. Myelogones are difficult to distinguish from lymphoblasts and monoblasts, unless one evaluates them in relation to the more mature forms usually associated with the younger cells. [myelo- + G. gone, seed]

myelogram (mi′e-lo-gram)
Radiographic contrast study of the spinal subarachnoid space and its contents. cervical m. contrast medium introduced directly into the cervical subarachnoid space, or moved with the help of gravity from the lumbar region, to outline the cervical cord and nerve roots. lumbar m. most common study for herniated nucleus pulposus or intervertebral disc protrusion.

myelography (mi′e-log′ra-fe)
Radiography of the spinal cord and nerve roots after the injection of a contrast medium into the spinal subarachnoid space. [myelo- + G. graphe, a drawing]

myeloic (mi-e-lo′ik)
Pertaining to the tissue and precursor cells from which neutrophils, eosinophils, and basophils are derived.

myeloid (mi′e-loyd)
1. Pertaining to, derived from, or manifesting certain features of the bone marrow. 2. Sometimes used with reference to the spinal cord. 3. Pertaining to certain characteristics of myelocytic forms, but not necessarily implying origin in the bone marrow. [myel- + -oid]

myeloidosis (mi′e-loy-do′sis)
General hyperplasia of myeloid tissue.

SYN: kathexis.

myeloleukemia (mi′e-lo-loo-ke′me-a)
A form of leukemia in which the abnormal cells are derived from myelopoietic tissue.

myelolipoma (mi′e-lo-li-po′ma)
Nodular accumulations of cells derived from localized proliferation of reticuloendothelial tissue in the blood sinuses of the adrenal glands; grossly, the nodules may seem to be adipose tissue, but actually are foci of bone marrow containing erythropoietic or myeloid cells.

myelolymphocyte (mi′e-lo-mon′o-sit)
Obsolete term for an abnormal form of the lymphocytic series in the bone marrow, and presumed to be formed in that tissue.

myelolysis (mi-e-lol′i-sis)
Decomposition of myelin.

myeloma (mi-e-lo′ma)
1. A tumor composed of cells derived from hemopoietic tissues of the bone marrow. 2. A plasma cell tumor. [myelo- + G. -oma, tumor] Bence Jones m. multiple m. in which the malignant plasma cells excrete only light chains of one type (either κ or λ); lytic bone lesions occur in about 60% of the cases, and light chains (Bence Jones protein) occur in the urine; amyloidosis and severe renal failure are more common than in multiple m.. SYN: L-chain disease, L-chain m.. endothelial m. SYN: Ewing tumor. giant cell m. SYN: giant cell tumor of bone. L-chain m. SYN: Bence Jones m.. multiple m., m. multiplex an uncommon disease that occurs more frequently in men than in women and is associated with anemia, hemorrhage, recurrent infections, and weakness. Ordinarily, it is regarded as a malignant neoplasm that originates in bone marrow and involves chiefly the skeleton, with clinical features attributable to the sites of involvement and to abnormalities in formation of plasma protein; characterized by numerous diffuse foci or nodular accumulations of abnormal or malignant plasma cells in the marrow of various bones (especially the skull), causing palpable swellings of the bones, and occasionally in extraskeletal sites; radiologically, the bone lesions have a characteristic punched-out appearance. The m. cells produce abnormal proteins in the serum and urine; those formed in any one example of multiple m. are different from other m. proteins, as well as from normal serum proteins, the most frequent abnormalities in the metabolism of protein being: 1) the occurrence of Bence Jones proteinuria, 2) a great increase in monoclonal γ-globulin in the plasma, 3) the occasional formation of cryoglobulin, and 4) a form of primary amyloidosis. The Bence Jones protein is not a derivative of abnormal serum protein, but seems to be formed de novo from amino acid precursors. SEE ALSO: plasma cell m.. SYN: multiple myelomatosis, myelomatosis multiplex, plasma cell m. (1) . nonsecretory m. multiple m. in which there is no detectable paraproteinemia or paraproteinuria. plasma cell m. 1. SYN: multiple m.. 2. plasmacytoma of bone, which is usually a solitary lesion and not associated with the occurrence of Bence Jones protein or other disturbances in the metabolism of protein (as observed in multiple m.). Some observers emphasize that the solitary lesion probably represents an early phase of classic multiple m., or an example of the latter in which only one focus is recognized.

myelomalacia (mi′e-lo-ma-la′she-a)
Softening of the spinal cord. [myelo- + G. malakia, a softness] angiodysgenetic m. SYN: subacute necrotizing myelitis.


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