| fluorescent antibody titre | An indirect method of measuring the concentration of an antibody in serum through the detection of fluorescent light emitted in a chemical reaction. (27 Sep 1997) |
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| fluorescent antinuclear antibody test | FANA test, a test for antinuclear antibody components; used, in particular, for the diagnosis of collagen-vascular diseases. (05 Mar 2000) |
| fluorescent dyes | Dyes that emit light when exposed to light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags. They are used as markers in biochemistry and immunology. (12 Dec 1998) |
| fluorescent in situ hybridization | See FISH. (12 Dec 1998) |
| fluorescent label | A molecule which fluoresces and can be attached to a probe molecule that does not fluoresce. (09 Oct 1997) |
| fluorescent microscope | <instrument> A microscope equipped to examine material that fluoresces under ultraviolet (UV) light. (12 Dec 1998) |
| fluorescent screen | A screen coated with fluorescent crystals such as the calcium tungstate used in the fluoroscope. (05 Mar 2000) |
| fluorescent stain | <technique> A stain or staining procedure using a fluorescent dye or substance that will combine selectively with certain tissue components and that will then fluoresce upon irradiation with ultraviolet or violet-blue light. (05 Mar 2000) |
| fluorescent treponemal antibody-absorption test | <investigation> A sensitive and specific serologic test for syphilis. It is more specific than the VDRL assay. The patient's serum is diluted to remove non-specific antibodies and then mixed on a glass slide with Nichol's strain of Treponema pallidum. If antibodies are present in the patient's serum they bind to the antigen and the bound antibodies are detected with fluoresceinated antihuman gamma-globulin antibody. Synonym: FTA-ABS test. (12 Sep2002) |
| aperture for electron microscopy | <technique> Anode aperture: The opening in the accelerating voltage anode shield of the electron gun through which the electrons must pass to irradiate the specimen. Condenser aperture: An opening in the condenser lens controlling the number of electrons entering the lens and the angular aperture of the electron beam. The angular aperture can also be controlled by the condenser lens current. Physical objective aperture: A metallic diaphragm, with a small central hole, used to limit the cone of electrons accepted by the objective lens. This improves image-contrast since highly scattered electrons are prevented from arriving at the Gaussian image plane and therefore cannot contribute to background fog. Aplanatic. Free from spherical aberration and coma. (05 Aug 1998) |
| bright field microscopy | <technique> Optical microscopy, in which absorption to a great extent and diffraction to a minor extent give rise to the image, as opposed to phase contrast or interference methods of microscopy. (18 Nov 1997) |
| ratio imaging fluorescence microscopy | <procedure> A method of measurement of intracellular pH or intracellular calcium levels, using a fluorescent probe molecule (see fura-2), in which the two different excitation wavelengths are used and the emitted light levels compared. If emission at one wavelength is sensitive to the intracellular ion level and emission at the other wavelength is not, then standardisation for intracellular probe concentration, efficiency of light collection, inactivation of probe and thickness of cytoplasm can all be performed automatically. (17 Dec 1997) |
| reflection X-ray microscopy | <technique> A method of producing enlarged images by means of X rays. In this method the radiation is totally reflected at glancing incidence from polished concave mirrors or from the curved surfaces of single crystals by Bragg reflection. The problem of aberration corrections still limits the resolution obtainable. (05 Aug 1998) |
| video microscopy | <technique> Microscopy that takes advantage of video as an imaging, image processing, analysing, or controlling device. (05 Aug 1998) |
| phase contrast microscopy | <investigation> A simple nonquantitative form of interference micoscopy of great utility in visualising live cells. Small differences in optical path length due to differences in refractive index and thickness of structures are visualised as differences in light intensity. (18 Nov 1997) |