| 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) |
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| 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 fibre | A part of the cone cell of the retina; the inner cone fibre is a slender axon-like part of the cone extending from the cell body to the pedicle located in the outer plexiform layer of the retina; in the outer fovea, where the cones are much elongated, they narrow to an (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) |
| pseudo-cone | <zoology> One of the soft gelatinous cones found in the compound eyes of certain insects, taking the place of the crystalline cones of others. Origin: Pseudo- + cone. Source: Websters Dictionary (01 Mar 1998) |
| s-cone | Short wavelength sensitive c. (blue c.). (05 Mar 2000) |
| pulmonary cone | The left or anterosuperior, smooth-walled portion of the cavity of the right ventricle of the heart, which begins at the supraventricular crest and terminates in the pulmonary trunk. Synonym: arterial cone, pulmonary cone, pulmonary conus. (05 Mar 2000) |