| collagen fibre | An individual fibre that varies in diameter from less than 1 um to about 12 um and is composed of fibrils; the fibre's, which are usually arranged in bundles, undergo some branching and are of indefinite length; chemically the fibre is a glycoprotein, collagen, which yields gelatin upon boiling; they make up the principal element of irregular connective tissue, tendons, aponeuroses, and most ligaments, and occur in the matrix of cartilage and osseous tissue. Synonym: white fibre. (05 Mar 2000) |
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| white fibre | White mammalian muscle fibres; larger in diameter than red fibres they have less myoglobin, sarcoplasm, and mitochondria, and contract more quickly. Synonym: collagen fibre. (05 Mar 2000) |
| cone | 1. <plant biology> In gymnosperms and club mosses, a group of sporophylls arranged compactly on a central axis, in the angiosperm family Casuarina, a woody multiple fruit incorporating the bracts and bracteoles associated with the flowers. 2. <physiology> The retinal cone responsible for colour vision. (03 Jul 1999) |
| cone biopsy | <gynaecology, procedure> A procedure which excises a cone of tissue (mucous membrane) off the cervix for purpose of diagnostics and therapeutics (removes precancerous cells). See: cervical dysplasia. (05 Jan 1998) |
| cone cell | <ophthalmology, physiology> One of the two photoreceptor cell types in the vertebrate retina. In cones the photopigment is in invaginations of the cell membrane of the outer segment. Cones are less sensitive to light than rods, and are differentially sensitive to particular wavelengths of light and therefore important for colour vision. They provide vision with higher spatial and temporal acuity, and it is the combination of signals from cones with different pigments that facilitates colour vision. There are three types of cones, each type sensitive to red, green or blue. Present in large numbers in the fovea. (03 Jul 1999) |
| cone cell of retina | 1. <plant biology> In gymnosperms and club mosses, a group of sporophylls arranged compactly on a central axis, in the angiosperm family Casuarina, a woody multiple fruit incorporating the bracts and bracteoles associated with the flowers. 2. <physiology> The retinal cone responsible for colour vision. (03 Jul 1999) |
| cone degeneration | A retinal abnormality in which colour perception is severely deficient and typical changes occur in electroretinogram. See: achromatopsia. Synonym: cone degeneration. (05 Mar 2000) |
| cone disks | Membranous disk's of flattened sacs about 14 nm thick that occur in the outer segment of cones of the retina. (05 Mar 2000) |
| cone down | To narrow a beam of X-rays to a region of interest using a collimator or cone; colloq., to delimit one's attention or activities. (05 Mar 2000) |
| cone dystrophy | A retinal abnormality in which colour perception is severely deficient and typical changes occur in electroretinogram. See: achromatopsia. Synonym: cone degeneration. (05 Mar 2000) |
| cone granule | Nucleus of a retinal cell connecting with one of the cones. (05 Mar 2000) |
| cone of light | A triangular area at the anterior inferior part of the tympanic membrane, running from the umbo to the periphery, where there is seen a bright reflection of light. Synonym: cone of light, light reflex, Politzer's luminous cone, red reflex, Wilde's triangle. Malacarne's pyramid, a lobule on the undersurface of the cerebellum, the posterior portion of the vermis. (05 Mar 2000) |
| cone vision | Vision when the eye is light-adapted. See: light adaptation, light-adapted eye. Synonym: cone vision, photopia. (05 Mar 2000) |
| muscle fibre | <pathology> Component of a skeletal muscle comprising a single syncytial cell that contains myofibrils. Any of the cells of skeletal or cardiac muscle tissue. Skeletal muscle fibres are cylindrical multinucleate cells containing contracting myofibrils, across which run transverse striations, enclosed in a sarcolemma. Cardiac muscle fibres contain one or sometimes two nuclei and myofibrils and are separated from one another by an intercalated disk; although striated, cardiac fibres branch to form an interlacing network. 2. fast-twitch muscles. Skeletal muscle fibres having high myofibrillar atpase activity, high glycolytic enzyme activities, and an intermediate glycogen content which produce a fast twitch. There are two types. Fast fatigable fibres, also called white fibres, have a low myoglobin content, and a small mitochondrial content, and fatigue rapidly due to their limited glycogen content and low capacity for oxidative metabolism. Fast fatigue-resistant fibres, also called red fibres, have a large mitochondrial content and a high myoglobin content, related to their resistance to fatigue. 3. slow-twitch muscles. Skeletal muscle fibres having low myofibrillar atpase activity, low glycogen content, and high myoglobin content, high mitochondrial oxidative enzyme activities, and an intermediate mitochondrial content which produce a slow twitch and are fatigue-resistant. (12 Dec 1998) |
| pole fibre | <cell biology> Microtubules inserted into the pole regions of the mitotic spindle (each pole is the product of the division of the centrioles and constitutes a microtubule organising centre. (18 Nov 1997) |