| congenital adrenal hyperplasia | <endocrinology> A genetic disorder present at birth characterised by a deficiency of the hormones aldosterone and cortisol and an overproduction of male sex hormones (androgens). In males this may manifest as enlarged penis, small testes and early development of masculine characteristics. In females features include ambiguous genitalia, failure to menstruate, deep voice and excessive hair. Origin: Gr. Plassein = to form (27 Sep 1997) |
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| congenital virilizing adrenal hyperplasia | A series of inherited inborn errors of metabolism with hyperplasia of the adrenal cortex and overproduction of virilizing hormones. Most common forms are due to partial or complete 21-hydroxylase deficiency, leading to increased ACTH production by the pituitary, stimulating adrenal growth and function. Severe form is characterised by salt-losing state. (05 Mar 2000) |
| foetal adrenal cortex | An extensive area of the adrenal gland present in primates during foetal life and for a short period after birth; located between the definitive cortex and the medulla, it contains large steroid-secreting cells arranged in a reticular pattern; involution of this zone in humans is largely completed by three months after birth. Synonym: androgenic zone, foetal reticularis, foetal zone, provisional cortex. (05 Mar 2000) |
| accessory | In anatomy, denoting certain muscles, nerves, glands, etc. That are auxiliary or supernumerary to some similar, generally more important thing. Synonym: accessorius. Origin: L. Accessorius, fr. Ac-cedo, pp. -cessus, to move toward (05 Mar 2000) |
| accessory atrium | <cardiology, embryology> A congenital anomaly characterised by the presence in the atrium of a perforated muscular membrane which separates the atrium into upper and lower chambers. (12 Dec 1998) |
| accessory auricles | Small, fleshy nodules or folds, sometimes with supporting cartilage, occasionally found along the margins of the embryonic branchial clefts. (05 Mar 2000) |
| accessory breast | A milk-secreting gland located elsewhere than at the normal place on the chest and existing in addition to the two usual mammae. Synonym: mamma accessoria, accessory breast, supernumerary mamma. (05 Mar 2000) |
| accessory canal | A channel leading from the root pulp laterally through the dentin to the periodontal tissue; may be found anywhere in the tooth root, but is more common in the apical third of the root. Synonym: lateral canal. (05 Mar 2000) |
| accessory cartilage | A sesamoid cartilage. (05 Mar 2000) |
| accessory cephalic vein | <anatomy, vein> A variable vein that passes along the radial border of the forearm to join the cephalic vein near the elbow. Synonym: vena cephalica accessoria. (05 Mar 2000) |
| accessory chromosome | A chromosome existing without its normal homologous chromosome; at the reduction division of gametogenesis an accessory chromosome is likely to be included in one daughter cell and not in the other, but may be lost completely by lagging behind on the equatorial plate. Synonym: monosome, odd chromosome, unpaired allosome, unpaired chromosome. (05 Mar 2000) |
| accessory cramp | <neurology> A wry neck, a contracted state of the cervical muscles, producing twisting of the neck and an unnatural position of the head. Origin: L. Tortus = twisted, collum = neck (18 Nov 1997) |
| accessory cuneate nucleus | A cell group lateral to the cuneate nucleus which receives posterior-root fibres corresponding to the proprioceptive innervation of the arm and hand; it projects to the cerebellum by way of the cuneocerebellar tract, and can be considered the upper-extremity equivalent of the thoracic nucleus. Synonym: nucleus cuneatus accessorius, external cuneate nucleus, lateral cuneate nucleus, Monakow's nucleus. (05 Mar 2000) |
| accessory flexor muscle of foot | <anatomy, muscle> Origin, by two heads from the lateral and medial borders of the inferior surface of the calcaneus; insertion, tendons of flexor digitorum longus; action, assists long flexor; nerve supply, lateral plantar. Synonym: musculus flexor accessorius, musculus quadratus plantae, accessory flexor muscle of foot, caro quadrata sylvii, musculus pronator pedis, plantar quadrate muscle, quadrate muscle of sole. (05 Mar 2000) |
| accessory flower part | <plant biology> Sepal and petal organs found on flowers. The sepals and petals are not essential for pollination but may aid in attracting insects or other organisms. (15 Jan 1998) |