| AI | accidental injury; accidentally incurred; adiposity index; aggregation index; allergy and immunology... |
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| AS | acetylstrophanthidin; acidified serum; acoustic schwannoma; acoustic stimulation; active sarcoidosis... |
| AVA | activity vector analysis; antiviral antibody; aortic valve area; aortic valve atresia; arteriovenous... |
| AVO | aortic valve opening; aortic valve orifice; atrioventricular opening |
| SAR | scatter/air ratio; seasonal allergic rhinitis; sexual attitude reassessment; slowly adapting recepto... |
| spindle cell sarcoma | <tumour> A malignant neoplasm, believed to be of mesenchymal origin, composed of elongated, spindle-shaped cells. Synonym: fascicular sarcoma. (05 Mar 2000) |
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| spindle fibre | <cell biology> Microtubules of the spindle that interdigitate at the equatorial plane with microtubules of the opposite polarity derived from the opposite pole microtubule organising centre. Usually distinguished from kinetochore fibres that are microtubules that link the poles with the kinetochore, although these could be included in a broader use of the term. (18 Nov 1997) |
| spindle-shaped | 1. Having the shape of a spindle. 2. <botany> Thickest in the middle, and tapering to both ends; fusiform; applied chiefly to roots. Source: Websters Dictionary (01 Mar 1998) |
| spindle-shaped muscle | <anatomy> One that has a fleshy belly, tapering at either extremity. Synonym: musculus fusiformis, spindle-shaped muscle. (05 Mar 2000) |
| neuromuscular spindle | A fusiform end organ in skeletal muscle in which afferent and a few efferent nerve fibres terminate; it contains from 3 to 10 striated muscle fibres (intrafusal fibres) that are much smaller than the ordinary muscle fibres, are separated from them by a capsule that encloses the organ, and are innervated by the thin axon of a gamma motoneuron (gamma motor fibre); the sensory endings that occur on the intrafusal fibres are either annulospiral or flower spray endings; this sensory end organ is particularly sensitive to passive stretch of the muscle in which it is enclosed. Synonym: Kuhne's spindle, muscle spindle. (05 Mar 2000) |
| neurotendinous spindle | <cell biology, physiology> A proprioceptive sensory nerve ending embedded among the fibres of a tendon, often near the musculotendinous junction; it is compressed and activated by any increase of the tendon's tension, caused either by active contraction or passive stretch of the corresponding muscle. Synonym: neurotendinous organ, neurotendinous spindle. (05 Mar 2000) |
| nevus, epithelioid and spindle cell | A benign compound nevus occurring most often in children before puberty, composed of spindle and epithelioid cells located mainly in the dermis, sometimes in association with large atypical cells and multinucleate cells, and having a close histopathological resemblance to malignant melanoma. The tumour presents as a smooth to slightly scaly, round to oval, raised, firm papule or nodule, ranging in colour from pink-tan to purplish red, often with surface telangiectasia. (12 Dec 1998) |
| nevus, spindle cell | A form of pigmented nevus showing intense melanocytic activity around the dermo-epidermal junction. Large numbers of spindle-shaped melanocytes proliferate downward toward the dermis and usually a large amount of pigment is present. It was first described in 1976 and the bulk of patients reported have been young females with the lesions presenting on the thighs. (12 Dec 1998) |
| nuclear spindle | See: spindle and mitosis. (18 Nov 1997) |
| Krukenberg's spindle | A vertical fusiform area of melanin pigmentation on the posterior surface of the central cornea. (05 Mar 2000) |
| Kuhne's spindle | A fusiform end organ in skeletal muscle in which afferent and a few efferent nerve fibres terminate; it contains from 3 to 10 striated muscle fibres (intrafusal fibres) that are much smaller than the ordinary muscle fibres, are separated from them by a capsule that encloses the organ, and are innervated by the thin axon of a gamma motoneuron (gamma motor fibre); the sensory endings that occur on the intrafusal fibres are either annulospiral or flower spray endings; this sensory end organ is particularly sensitive to passive stretch of the muscle in which it is enclosed. Synonym: Kuhne's spindle, muscle spindle. (05 Mar 2000) |
| abdominal aortic aneurysm | <surgery> A distended and weakened area in the wall of the abdominal aorta, more common in those who suffer from atherosclerosis. Symptoms include sudden, severe abdominal pain with radiation to the back. (27 Sep 1997) |
| abdominal aortic coarctation | <radiology> 2% of all coarctations, (most common site is thoracic: just distal to origin of L SCA), may be isolated congenital anomaly, associated with: thoracic aortic coarctation, idiopathic hypercalcaemia syndrome, rubella syndrome (ToRCHS), Takayasu arteritis, neurofibromatosis, radiation therapy, fibromuscular disease (12 Dec 1998) |
| abdominal aortic plexus | <anatomy, neurology> An autonomic plexus surrounding the abdominal aorta, directly continuous with the thoracic aortic plexus above and continued inferior to the bifurcation of the aorta as the superior hypogastric plexus. Synonym: plexus aorticus abdominalis. (05 Mar 2000) |
| acute aortic dissection | <cardiology> A condition in which a weakened portion of the thoracic aorta begins to tear along the longitudinal axis of the vessel. Symptoms include sudden, severe chest pain that may radiate to the back accompanied by nausea, sweating and difficulty breathing. A common risk factor for this event is atherosclerotic vascular disease and-or hypertension. Advanced cases of syphilis (syphilitic aortitis) can also result in acute thoracic dissection as a complication of infection with Treponema pallidum. (27 Sep 1997) |