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Medical Dictionary


anospinal (a′no-spi′nal)
Relating to the anus and the spinal cord.

anosteoplasia (an-os′te-o-pla′ze-a)
Failure of bone formation. [G. an- priv. + osteon, bone, + plasso, to form]

anostosis (an-os-to′sis)
Failure of ossification. [G. an- priv. + osteon, bone]

anotia (an-o′she-a)
Congenital absence of one or both auricles of the ears. [G. an- priv. + ous, ear] ADC Abbreviation for AIDS dementia complex.

Abbreviation for antibody-dependent cell-mediated cytotoxicity.

Abbreviation for L. a., add; L. addantur, let them be added; addendus, to be added; and addendo, by adding.

Common name for many members of the family Viperidae (the vipers), applied to several genera, although true adders are of the genus Vipera. [M.E. naddre, fr. O.E. naedre]

addict (ad′ikt)
A person who is habituated to a substance or practice, especially one considered harmful or illegal.

addiction (a-dik′shun)
Habitual psychological and physiologic dependence on a substance or practice that is beyond voluntary control. [L. ad-dico, pp. -dictus, consent, fr. ad- + dico, to say] alcohol a. SYN: alcoholism.

Thomas, U.S. internist, 1881–1949. See A. count.

Thomas, English physician, 1793–1860. See A. anemia, A. disease, addisonian anemia, addisonian crisis, A.-Biermer disease.

Christopher, English anatomist, 1869–1951. See A. clinical planes, under plane.

addisonian (ad-i-so′ne-an)
Relating to or described by Thomas Addison; used in relation to pernicious anemia or the various features of Addison disease.

additive (ad′i-tiv)
1. A substance not naturally a part of a material ( e.g., food) but deliberately added to fulfill some specific purpose ( e.g., preservation). 2. Tending to add or be added; denoting addition. 3. In metrical studies ( e.g., genetics, epidemiology, physiology, statistics), having the property that the total combined effect of two or more factors equals the sum of their individual effects in isolation. Cf.:synergism.

additivity (ad-i-tiv′i-te)
The quality or state of being additive. causal a. the relationship between two or more causal components such that their combined effect is the algebraic sum of their individual effects. interlocal a. the relationship among quantitative effects of different genetic loci such that their joint effect is equal to the sum of their individual effects; an absence of epistasis or interaction. intralocal a. the relationship between alleles such that the quantifiable phenotype of the heterozygote is at the midpoint between those for the two homozygotes; an absence of dominance.

addressin (ad-res′in)
A molecule on the surface of a cell that serves as a homing device to direct another molecule to a specific location. [address, fr. O.Fr. adresser, to direct, fr. L.L. addirectiare, fr. L. ad, to, + directus, straight, direct, + -in]

adducent (a-doo′sent)
Bringing toward; adducting. [L. adducens, pres. p. of ad-duco, to bring]

adducin (a-doo′sen)
A protein that binds to spectrin and actin and links the spectrin assembly.

adduct (a-dukt′)
1. To draw toward the median plane. 2. An addition product, or complex, or one part of the same. [L. ad-duco, pp. -ductus, to bring toward]

adduction (a-duk′shun)
1. Movement of a body part toward the median plane (of the body, in the case of limbs; of the hand or foot, in the case of digits). 2. Monocular rotation (duction) of the eye toward the nose. 3. A position resulting from such movement. Cf.:abduction.

adductor (a-duk′ter, tor)
SYN: a. muscle.

Abbreviation for adenine.

adelomorphous (a-del-o-mor′fus)
Of not clearly defined form. In the past this term was applied to certain cells of the gastric glands. [G. adelos, uncertain, not clear, + morphe, shape]

See adeno-.

adenalgia (ad-e-nal′je-a)
Rarely used term for pain in a gland. [aden- + G. algos, pain]

adendric (a-den′drik)
SYN: adendritic.

adendritic (a-den-drit′ik)
Without dendrites. SYN: adendric. [G., a- priv. + dendron, tree]

adenectomy (ad-e-nek′to-me)
Excision of a gland. [aden- + G. ektome, excision]

adenectopia (ad′e-nek-to′pe-a)
Presence of a gland other than in its normal anatomical position. [aden- + G. ek, out of, + topos, place]

adenemphraxis (ad′e-nem-frak′sis)
Rarely used term for an obstruction to the discharge of a glandular secretion. [aden- + G. emphraxis, stoppage]

adeniform (a-den′i-form)
SYN: adenoid (1) .

adenine (A, Ade) (ad′e-nen)
One of the two major purines (the other being guanine) found in both RNA and DNA, and also in various free nucleotides of importance to the body, such as AMP (adenylic acid), ATP, NAD+ and NADP+, and FAD; in all these smaller compounds, a. is condensed with ribose at nitrogen-9, forming adenosine. For structure, see adenylic acid. SYN: 6-aminopurine. a. arabinoside misnomer for arabinosyladenine. a. deaminase an enzyme that catalyzes the hydrolysis of a. to ammonia and hypoxanthine. A part of purine degradation. a. deoxyribonucleotide SYN: deoxyadenylic acid. a. nucleotide SYN: adenylic acid. a. phosphoribosyltransferase an enzyme that catalyzes the reaction of a. with 5-phospho-α-d-ribose 1-diphosphate (PRPP) to form AMP and pyrophosphate. An important step in purine salvage. A deficiency of this enzyme can lead to 2,8-dihydroxyadenine lithiasis. a. sulfate a. conjugated with sulfuric acid; used to stimulate leukocyte production in agranulocytosis.

adenitis (ad-e-ni′tis)
Inflammation of a lymph node or of a gland. [aden- + G. -itis, inflammation] mesenteric a. an illness with abdominal pain and fever due to enlargement and inflammation of the mesenteric lymph nodes; often mistaken for appendicitis. SYN: mesenteric lymphadenitis.

adenization (ad-e-ni-za′shun)
Conversion into glandlike structure.

adeno-, aden-
Combining forms denoting gland, glandular; corresponds to L. glandul-, glandi-. [G. aden, adenos a gland]

adenoacanthoma (ad′e-no-ak-an-tho′ma)
A malignant neoplasm consisting chiefly of glandular epithelium (adenocarcinoma), usually well differentiated, with foci of squamous (or epidermoid) neoplastic cells.

adenoameloblastoma (ad′e-no-am′el-o-blast-o′ma)
SYN: adenomatoid odontogenic tumor.

adenoblast (ad′e-no-blast)
A proliferating embryonic cell with the potential to form glandular parenchyma. [adeno- + G. blastos, germ]

adenocarcinoma (ad′e-no-kar-si-no′ma)
A malignant neoplasm of epithelial cells in glandular or glandlike pattern. SYN: glandular cancer, glandular carcinoma. acinic cell a. an a. arising from secreting cells of a racemose gland, particularly the salivary glands. SYN: acinar carcinoma, acinic cell carcinoma. alveolar a. a. of the lung in which tumor cells form structures resembling alveoli. a. in Barrett esophagus an a. arising in the esophagus that has become lined with columnar cells (Barrett mucosa). bronchiolar a. SYN: alveolar cell carcinoma. bronchioloalveolar a. SYN: alveolar cell carcinoma. clear cell a. 1. a histologic type of renal a.; 2. a histologic type of a. occurring chiefly in the male and female genitourinary tracts that is characterized by distinctive hobnail cell growth of neoplastic cells in sheets, papillae, and coalescing glands. mesonephric a. SYN: mesonephroma. mucoid a. sometimes applied to mucinous carcinoma, or a. containing mucin secreting neoplastic cells. papillary a. an a. containing fingerlike processes of vascular connective tissue covered by neoplastic epithelium, projecting into cysts or the cavity of glands or follicles; occurs most frequently in the ovary and thyroid gland. renal a. an a. arising in the renal parenchyma, usually occurring in middle-aged or older people of either sex (although more common in males). SYN: clear cell carcinoma of kidney, renal cell carcinoma. a. in situ a noninvasive abnormal proliferation of glands believed to precede the appearance of invasive a.; reported in the endometrium, breast, large intestine, cervix, and other sites.

adenocystoma (ad′e-no-sis-to′ma)
Adenoma in which the neoplastic glandular epithelium forms cysts.

adenocyte (ad′e-no-sit)
A secretory cell of a gland. [adeno- + G. kytos, a hollow (cell)]

adenodiastasis (ad′e-no-di-as′ta-sis)
Separation or ectopia of glands or glandular tissue from their usual anatomical sites, e.g., pancreatic glands in the wall of the small intestine, gastric glands in the wall of the esophagus. [adeno- + G. diastasis, a separation]

adenodynia (ad′e-no-din′e-a)
Rarely used term for adenalgia. [adeno- + G. odyne, pain]

adenofibroma (ad′e-no-fi-bro′ma)
A benign neoplasm composed of glandular and fibrous tissues, with a relatively large proportion of glands.

adenofibrosis (ad′e-no-fi-bro′sis)
SYN: sclerosing adenosis.

adenogenous (ad-e-noj′en-us)
Having an origin from glandular tissue.

adenohypophysial (ad′e-no-hi-po-fiz′e-al)
Relating to the adenohypophysis.

adenohypophysis (ad′e-no-hi-pof′i-sis) [TA]
The anterior pituitary gland; it consists of the distal part, intermediate part, and infundibular part. SEE ALSO: pituitary gland. SYN: lobus anterior hypophyseos [TA] , anterior lobe of hypophysis&star, glandular lobe of hypophysis, lobus glandularis hypophyseos.

adenohypophysitis (ad′e-no-hi-pof-i-si′tis)
Inflammatory and fibriotic reaction affecting the anterior pituitary gland, often related to pregnancy. lymphocytic a. a diffuse lymphocytic infiltration of the adenohypophysis, often related to pregnancy; probably a disturbance in the immune system.

adenoid (ad′e-noyd)
1. Glandlike; of glandular appearance. SYN: adeniform. 2. See pharyngeal tonsil. [adeno- + G. eidos, appearance]

adenoidectomy (ad′e-noy-dek′to-me)
An operation for the removal of adenoid tissue in the nasopharynx. [adenoid + G. ektome, excision]

adenoiditis (ad′e-noy-di′tis)
Inflammation of adenoid tissue.

adenoids (ad′e-noydz)
1. A normal collection of unencapsulated lymphoid tissue in the nasopharynx. Also called pharyngeal tonsils. 2. Common terminology for the large (normal) pharyngeal tonsils of children. [G. aden, gland, + -eidos, resemblance]

adenolipoma (ad′e-no-li-po′ma)
A benign neoplasm composed of glandular and adipose tissues. [G. aden, gland, + lipos, fat, + -oma, tumor]

adenolipomatosis (ad′e-no-lip′o-ma-to′sis)
A condition characterized by development of multiple adenolipomas. symmetric a. SYN: multiple symmetric lipomatosis.

adenolymphocele (ad′e-no-lim′fo-sel)
Cystic dilation of a lymph node following obstruction of the efferent lymphatic vessels. [adeno- + L. lympha, spring water, + G. kele, tumor]

adenolymphoma (ad′e-no-lim-fo′ma)
Obsolete term for a benign glandular tumor usually arising in the parotid gland and composed of two rows of eosinophilic epithelial cells, which are often cystic and papillary, together with a lymphoid stroma. SYN: papillary cystadenoma lymphomatosum, Warthin tumor.

adenoma (ad-e-no′ma)
A benign epithelial neoplasm in which the tumor cells form glands or glandlike structures; usually well circumscribed, tending to compress rather than infiltrate or invade adjacent tissue. [adeno- + G. -oma, tumor] acidophil a. a tumor of the adenohypophysis in which cell cytoplasm stains with acid dyes; often growth hormone–producing. SYN: eosinophil a.. ACTH-producing a. a pituitary tumor composed of corticotrophs that produce ACTH, often a basophilic a.; may give rise to Cushing disease or Nelson syndrome. adnexal a. an a. arising in, or forming structures resembling, skin appendages. adrenocortical a. a benign tumor of adrenal cortical cells; small unencapuslated nodules of adrenal cortex are probably localized areas of hyperplasia rather than adenomas; true adenomas are rare and may be symptomless or associated with Cushing syndrome or primary aldosteronism. apocrine a. SYN: papillary hidradenoma. basal cell a. a benign tumor of major or minor salivary glands or other organs composed of small cells showing peripheral palisading. basophil a. a tumor of the adenohypophysis in which the cell cytoplasm stains with basic dyes, often ACTH-producing. bronchial a. obsolete term once used to encompass carcinoid tumors, mucoepidermoid carcinoma, and adenoid cystic carcinoma. Cf.:bronchial mucous gland a.. bronchial mucous gland a. a rare benign tumor arising from the mucous glands of bronchial mucosa. canalicular a. (ca-na-lik′oo-lar) a variant of monomorphic a. composed of double rows of epithelial cells in long cords. chromophobe a., chromophobic a. a tumor of the adenohypophysis whose cells do not stain with either acid or basic dyes. colloid a. a follicular a. of the thyroid, composed of large follicles containing colloid. SYN: macrofollicular a.. embryonal a. a benign neoplasm in which the glandular epithelial elements are not fully differentiated, resembling immature tissue observed in embryonic development. eosinophil a. SYN: acidophil a.. follicular a. an a. of the thyroid with a simple glandular pattern. Fuchs a. a benign epithelial tumor of the nonpigmented epithelium of the ciliary body, rarely exceeding 1 mm in diameter. gonadotropin-producing a. a rare type of pituitary a. that produces FSH and LH; its cells can be identified only by immunochemical techniques. growth hormone–producing a. an a. that produces the clinical picture of gigantism or acromegaly, although a third of the cells have no granules or are a mixture of acidophils and chromophobes; some tumors may secrete both growth hormone and prolactin; often an acidophil or eosinophil a.. hepatic a. a benign tumor of the liver, usually occurring in women during the reproductive years in association with lengthy oral contraceptive use. The tumor is usually solitary, subcapsular, and large, composed of cords of hepatocytes with portal triads. SYN: hepatocellular a.. hepatocellular a. SYN: hepatic a.. Hürthle cell a. an uncommon type of thyroid tumor characterized by abundant eosinophilic cytoplasm containing numerous mitochondria. Often malignant with widespread metastases; rarely takes up radioiodine. SEE ALSO: Hürthle cell carcinoma. SYN: oncocytic a.. invasive pituitary a. extensive infiltrates of the dura, bone, and sinuses. lactating a. an uncommon a. of the breast composed of tubuloacinar structures with pronounced secretory changes such as seen in pregnancy and lactation. macrofollicular a. SYN: colloid a.. mammosomatotroph cell a. a rare prolactin- and growth hormone–producing pituitary a. composed of ultrastructurally monomorphic cells with both somatotrophic and lactotrophic differentiation. microfollicular a. a fetal a. of the thyroid composed of very small follicles and solid alveolar groups of thyroid epithelial cells. monomorphic a. a benign ductal neoplasm of the salivary glands, with a uniform epithelial pattern and lacking the chondromyxoid stroma of a pleomorphic a.. nephrogenic a. a benign tumor of the urinary bladder or urothelial mucosa, composed of glandular structures resembling renal tubules. a. of nipple SYN: subareolar duct papillomatosis. null-cell a. an a. of the hypophysis composed of cells for which there is no overt evidence of hormone production, but which usually produces hypopituitarism and visual disturbances by compression of adjacent structures; approximately one third of these tumors have cells with abundant mitochondria (oncocytes) that are somewhat larger than the monocytic null cells. SYN: undifferentiated cell a.. oncocytic a. SYN: Hürthle cell a.. oxyphil a. SYN: oncocytoma. papillary cystic a. an a. in which the lumens of the acini are frequently distended by fluid, and the neoplastic epithelial elements tend to form irregular, fingerlike projections. papillary a. of large intestine SYN: villous a.. pituitary a. a benign neoplasm of the pituitary generally arising in the adenohypophysis. pleomorphic a. SYN: mixed tumor of salivary gland. polypoid a. SYN: adenomatous polyp. prolactin-producing a. a pituitary a. composed of prolactin-producing cells; it gives rise to symptoms of nonpuerperal amenorrhea and galactorrhea (Forbes-Albright syndrome) in women and to impotence in men. SYN: prolactinoma. prostatic a. the growth in benign prostatic hyperplasia. renal cortical a. an a., usually small, sometimes found in the renal cortex incidentally at autopsy and derived from renal tubular tissue. sebaceous a. a benign neoplasm of sebaceous tissue, with a predominance of mature secretory sebaceous cells. Cf.:a. sebaceum. a. sebaceum archaic misnomer for a hamartoma occurring on the face, composed of fibrovascular tissue and appearing as an aggregation of red or yellow papules that may be associated with tuberous sclerosis; sebaceous glands may be present but are not increased. Cf.:sebaceous a.. SYN: Pringle disease. thyrotropin-producing a. a rare pituitary a. usually associated with hypo- or hyperthyroidism. tubular a. 1. a benign neoplasm composed of epithelial tissue resembling a tubular gland. 2. dysplastic polyp of the colonic mucosa which is considered a potential precursor of adenocarcinoma. undifferentiated cell a. SYN: null-cell a.. villous a. frequently appears as a solitary, sessile, often large, tumor of colonic mucosa, although it can occur anywhere through the GI tract; composed of mucinous epithelium covering delicate vascular projections; malignant change occurs frequently; hypersecretion occurs rarely. Also known as a.. SYN: papillary a. of large intestine.

adenomatoid (ad-e-no′ma-toyd)
Resembling an adenoma.


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