| white infarct | An infarct in which little or no bleeding into tissue spaces occurs when the blood supply is obstructed. Synonym: pale infarct, white infarct. (05 Mar 2000) |
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| white lead | A heavy white powder that is insoluble in water; occasionally, it is used to relieve irritation in dermatitis, but it is used largely in the manufacture of paint and in the arts and is thus productive of lead poisoning. Synonym: ceruse, white lead. (05 Mar 2000) |
| white leg | An extreme edematous swelling of the leg following childbirth, due to thrombosis of the iliofemoral veins. Synonym: leukophlegmasia dolens, milk leg, puerperal phlebitis, thrombotic phlegmasia, white leg. (05 Mar 2000) |
| white level | <microscopy> Also reference white level. The IEEE scale, or voltage level, of the video picture signal that corresponds to a specified maximum limit for white peaks. (05 Aug 1998) |
| white line | A pale streak appearing within 30 to 60 seconds after stroking the skin with a fingernail, and lasting for several minutes; regarded as a sign of diminished arterial tension. Synonym: Sergent's white line. (05 Mar 2000) |
| white line of anal canal | A bluish pink, narrow, wavy zone in the mucosa of the anal canal below the pectinate line at the level of the interval between the subcutaneous part of the external sphincter and the lower border of the internal sphincter, said to be palpable. Synonym: Hilton's white line. (05 Mar 2000) |
| white line of frankel | <radiology> Dense zone of provisional calcification at edge of metaphysis, just beneath physis seen in scurvy (12 Dec 1998) |
| white line of Toldt | Lateral reflection of posterior parietal pleura of abdomen over the mesentery of the ascending and descending colon. Junction of parietal peritoneum with Denonvillieri's fascia. (05 Mar 2000) |
| white matter | <anatomy> Brain tissue composed of myelin-coated nerve cell fibres. White matter carries information between the nerve cells in the brain and spinal cord. The inner portion of the cerebrum is composed of white matter. See: grey matter. (13 Nov 1997) |
| white-matter disease | <radiology> Demyelinating (myelinoclastic), destruction of existing myelin, acquired diseases with inflammatory characteristics, includes: MS, PML, encephalomyelitis, also may be due to anoxia, infarct, tumour, radiation dysmyelinating, abnormal myelin formation or maintenance, two groups: primary white-matter diseases: leukodystrophies, involve gray matter: Niemann-Pick, Gaucher, Tay-Sachs (12 Dec 1998) |
| white mercuric precipitate | Used in ointment for the treatment of skin diseases. Synonym: ammoniated mercuric chloride, white mercuric precipitate. (05 Mar 2000) |
| white muscle | <anatomy> A rapid or fast-twitch muscle in which pale large "white" fibres predominate; mitochondria and myoglobin are relatively sparse compared with red muscle; involved in phasic contraction. (05 Mar 2000) |
| white muscle disease | A myodegeneration most frequent in calves and lambs whose dams have been fed during gestation or longer on feeds, especially legumes, grown in certain areas where selenium is either deficient or unavailable in the soil. It has been recorded in many countries. It has been produced experimentally in several species of animals on low-selenium intake. A similar myopathy occurs naturally in goats, deer, foals, and dogs but proof of the aetiology is lacking. (merck veterinary manual, 5th ed) (12 Dec 1998) |
| white mustard | The ripe seeds of Brassica (Sinapis) alba; less pungent than black mustard, but with the same constituents and uses. (05 Mar 2000) |
| white-out syndrome | <syndrome> A psychosis which occurs in Arctic explorers or others similarly exposed to the stimulus deprivation of a snow-clad environment. See: sensory deprivation. (05 Mar 2000) |