| GDNF | giant cell line-derived neutrophilic factor |
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| GIP | gastric inhibitory polypeptide; giant cell interstitial pneumonia; glucose-dependent insulinotropic ... |
| GMC | general medical clinic; general medical council; giant migratory contraction; grivet monkey cell |
| MCGC | metacerebral giant cell |
| MGCE | multifocal giant cell encephalitis |
| pyramidal muscle of auricle | <anatomy> An occasional prolongation of the fibres of the tragicus to the spina helicis. Synonym: musculus pyramidalis auriculae, Jung's muscle, pyramidal muscle of auricle. (05 Mar 2000) |
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| pyramidal process | The portion of the palatine bone passing lateral and posterior from the angle formed by the vertical and horizontal plates. Synonym: processus pyramidalis. (05 Mar 2000) |
| pyramidal radiation | Corticospinal fibres passing from the cortex into the pyramid. Synonym: radiatio pyramidalis. (05 Mar 2000) |
| pyramidal tract | A massive bundle of fibres originating from pyramidal cells of various sizes in the fifth layer of the precentral motor (area 4), the premotor area (area 6), and to a lesser extent from the postcentral gyrus. Cells of origin in area 4 include the gigantopyramidal cells of Betz. Fibres from these cortical regions descend through the internal capsule, the middle third of the crus cerebri, and the ventral part of the pons to emerge on the ventral surface of the medulla oblongata as the pyramis. Continuing caudally, most of the fibres cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord as the lateral pyramidal tract, which distributes its fibres throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. In the (extremity-related) spinal cord enlargements, fibres also pass directly to motoneuronal groups that innervate distal extremity muscles subserving particular hand-and-finger or foot-and-toe movements. The uncrossed fibres form a small bundle, the anterior pyramidal tract, which descends in the anterior funiculus of the spinal cord and terminates in synaptic contact with interneurons in the medial half of the anterior horn on both sides of the spinal cord. Interruption of the pyramidal tract at or below its cortical origin causes impairment of movement in the opposite body-half, especially severe in the arm and leg; characterised by muscular weakness, spasticity and hyperreflexia, and a loss of discrete finger and hand movements. Babinski's sign is associated with this condition of hemiplegia. Synonym: tractus corticospinalis, tractus pyramidalis, corticospinal tract. (05 Mar 2000) |
| pyramidal tractotomy | May be mesencephalic (pedunculotomy or crusotomy), medullary (medullary pyramidotomy), or spinal (spinal pyramidotomy). (05 Mar 2000) |
| direct pyramidal tract | Uncrossed fibres forming a small bundle in the pyramidal tract. See: pyramidal tract. Synonym: tractus corticospinalis anterior, tractus pyramidalis anterior, anterior corticospinal tract, anterior pyramidal fasciculus, direct pyramidal tract, fasciculus corticospinalis anterior, fasciculus pyramidalis anterior, Turck's bundle, Turck's column, Turck's tract. (05 Mar 2000) |
| lateral pyramidal fasciculus | Those fibres of the pyramidal tract that cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord; they are distributed throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. See: pyramidal tract. Synonym: tractus corticospinalis lateralis, tractus pyramidalis lateralis, crossed pyramidal tract, fasciculus corticospinalis lateralis, fasciculus pyramidalis lateralis, lateral corticospinal tract, lateral pyramidal fasciculus. (05 Mar 2000) |
| lateral pyramidal tract | Those fibres of the pyramidal tract that cross to the opposite side in the pyramidal decussation and descend in the dorsal half of the lateral funiculus of the spinal cord; they are distributed throughout the length of the spinal cord to interneurons of the zona intermedia of the spinal gray matter. See: pyramidal tract. Synonym: tractus corticospinalis lateralis, tractus pyramidalis lateralis, crossed pyramidal tract, fasciculus corticospinalis lateralis, fasciculus pyramidalis lateralis, lateral corticospinal tract, lateral pyramidal fasciculus. (05 Mar 2000) |
| benign giant lymph node hyperplasia | Solitary masses of lymphoid tissue containing concentric perivascular aggregates of lymphocytes, occurring usually in the mediastinum or hilar region of young adults; similar changes have been reported outside the mediastinum and, if associated with interfollicular sheets of plasma cells, may progress to lymphoma or plasmacytoma. Synonym: angiofollicular mediastinal lymph node hyperplasia, Castleman's disease. (05 Mar 2000) |
| giant | 1. A man of extraordinari bulk and stature. "Giants of mighty bone and bold emprise." 2. A person of extraordinary strength or powers, bodily or intellectual. 3. Any animal, plant, or thing, of extraordinary size or power. Giant's Causeway, a vast collection of basaltic pillars, in the county of Antrim on the northern coast of Ireland. Origin: OE. Giant, geant, geaunt, OF. Jaiant, geant, F. Geant, L. Gigas, fr. Gr, from the root of E. Gender, genesis. See Gender, and cf. Gigantic. Like a giant; extraordinary in size, strength, or power; as, giant brothers; a giant son. Giant cell. <anatomy> A very large African heron (Ardeomega goliath). It is the largest heron known. Giant kettle, a pothole of very large dimensions, as found in Norway in connection with glaciers. See Pothole. Giant powder. See Nitroglycerin. <botany> Giant puffball, one of several species of very large squids, belonging to Architeuthis and allied genera. Some are over forty feet long. Source: Websters Dictionary (01 Mar 1998) |
| giant axon | <biology> Extraordinarily large unmyelinated axons found in invertebrates. Some, like the squid giant axon, can approach 1 mm diameter. Large axons have high conduction speeds, the giant axons are invariably involved in panic or escape responses and may (e.g. Crayfish) have electrical synapses to further increase speed. Vertebrate axons with high conduction velocites are much narrower: they are myelinated, allowing saltatory conduction. (17 Dec 1997) |
| giant axonal neuropathy | <paediatrics> A rare disorder beginning at or after the third year of life, and presenting clinically with kinky hair, progressive painless clumsiness, muscle weakness and atrophy, sensory loss, and areflexia. Pathologically, both myelinated and unmyelinated nerve fibres contain axonal spheroids packed with neurofilaments; sporadic in nature. (05 Mar 2000) |
| giant cells, foreign-body | Multinucleated cells (fused macrophages), characteristic of granulomatous inflammation, which form around exogenous material in the skin. They are similar in appearance to langhans giant cells (giant cells, langhans), but foreign-body giant cells have more abundant chromatin and their nuclei are scattered in an irregular pattern in the cytoplasm. (12 Dec 1998) |
| giant cells, langhans | Multinucleated cells (fused macrophages) seen in granulomatous inflammations such as tuberculosis, syphilis, sarcoidosis, and deep fungal infections. They resemble foreign-body giant cells (giant cells, foreign body) but langhans giant cells contain less chromatin and their nuclei are arranged peripherally in a horseshoe-shaped pattern. Langhans giant cells occur frequently in delayed hypersensitivity. (12 Dec 1998) |
| giant chromosome | <cell biology> Giant chromosomes produced by the successive replication of homologous pairs of chromosomes, joined together (synapsed) without chromosome separation or nuclear division. They thus consist of many up to 1000) identical chromosomes (strictly chromatids) running parallel and in strict register. The chromosomes remain visible during interphase and are found in some ciliates, ovule cells in angiosperms and in larval Dipteran tissue. The best known polytene chromosomes are those of the salivary gland of the larvae of Drosophila melanogaster which appear as a series of dense bands interspersed by light interbands, in a pattern characteristic for each chromosome. The bands, of which there are about 5,000 in Drosophila melanogaster, contain most of the DNA (ca 95%) of the chromosomes and each band roughly represents one gene. The banding pattern of polytene chromosomes provides a visible map to compare with the linkage map determined by genetic studies. Some segments of polytene chromosome show chromosome puffs, areas of high transcription. (18 Nov 1997) |