| white rami communicantes | Short nerves arising from the initial portion of the ventral primary rami of the thoracic and upper lumbar spinal nerves through which all presynaptic sympathetic nerve fibres must pass to reach the sympathetic trunks; also conveyed by the white rami communicans are visceral afferent (sensory) fibres which were conveyed to the sympathetic trunks in splanchnic nerves. Most fibres conveyed by the white rami communicantes are myelinated. Synonym: rami communicantes nervorum spinalium, communicating branches of spinal nerves. (05 Mar 2000) |
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| white reaction | The response seen in many individuals after the skin is lightly stroked with a blunt instrument; it is attributed to capillary action. (05 Mar 2000) |
| white soft paraffin | white petrolatum |
| white sponge nevus | An autosomal dominant condition of the oral cavity characterised by soft, white or opalescent, thickened and corrugated folds of mucous membrane; other mucosal sites are occasionally involved simultaneously. Synonym: familial white folded dysplasia, oral epithelial nevus. (05 Mar 2000) |
| white spot | Gray-white or white, rounded or irregularly shaped, slightly opaque patches or spots that are sometimes observed postmortem in the epicardium, especially in middle-aged or older persons; they result from fibrous thickening, and sometimes hyalinization, of the epicardium; similar lesions may also occur in the visceral layer of the peritoneum. Synonym: macula lactea, macula tendinea, tache blanche, tache laiteuse, tendinous spot, white spot. (05 Mar 2000) |
| white spot disease | Small discrete, white, waxy, indurated lesions due to localised degenerative changes in the fibrous tissue. Synonym: white spot disease. (05 Mar 2000) |
| white substance | <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 thrombus | A thrombus of opaque dull white colour composed essentially of blood platelets. Synonym: pale thrombus. (05 Mar 2000) |
| white turpentine | Turpentine from Pinus palustris. (05 Mar 2000) |
| white-water | <veterinary> A dangerous disease of sheep. Source: Websters Dictionary (01 Mar 1998) |
| white wax | Yellow wax bleached by being rolled very thin and exposed to the light and air, or bleached by chemical oxidants; same uses as yellow wax. Synonym: bleached wax, white beeswax. (05 Mar 2000) |
| white yolk | Yolk consisting of much finer particles than those of yellow yolk; thin layers of it lie between the zones of yellow yolk and form the latebra. (05 Mar 2000) |
| wolff-parkinson-white syndrome | <syndrome> A form of pre-excitation characterised by a short pr interval and a long qrs interval with a delta wave. (12 Dec 1998) |
| Wolf Parkinson White syndrome | <cardiology, syndrome> Abnormal cardiac conduction that occurs by way of an accessory pathway between the atria and the ventricles. Baseline ECG will typically show a short P-R interval and a slurred upstroke of the QRS (delta wave). Tachyarrhythmias are common. (27 Sep 1997) |
| posterior white column of the spinal cord | The large wedge-shaped fibre bundle lying between the posterior gray column and the posterior median septum, and composed largely of dorsal root fibres. Synonym: funiculus posterior, dorsal funiculus, funiculus dorsalis. (05 Mar 2000) |