| regressive staining | A type of staining in which tissues are overstained and the excess dye is then removed selectively until the desired intensity is obtained. (05 Mar 2000) |
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| progressive staining | A procedure in which staining is continued until the desired intensity of colouring of tissue elements is attained. (05 Mar 2000) |
| homogeneously staining region | <molecular biology> A region on a chromosome which, when stained, is uniform in appearance. (Normally, a stained chromosome shows a banding pattern.) Homogeneously staining regions contain multiple copies of a single gene. (09 Oct 1997) |
| silver staining | The use of silver, usually silver nitrate, as a reagent for producing contrast or colouration in tissue specimens. (12 Dec 1998) |
| staining | The use of a dye, reagent, or other material for producing colouration in tissues or microorganisms for microscopic examination. (12 Dec 1998) |
| negative staining | Microscopic technique in which the object stands out against a dark background of stain. For electron microscopy the sample is suspended in a solution of an electron dense stain such as sodium phosphotungstate and then sprayed onto a support grid. The stain dries as structureless solid and fills all crevices in the sample. When examined in the electron microscope the sample appears as a light object against a dark background. Quite fine structural detail can be observed using negative staining and it has been used extensively to study the structure of viruses and other particulate samples. (18 Nov 1997) |
| dispersion staining | <microscopy> A procedure involving central or annular stops in the objective back focal plane to induce coloured images of transparent particles mounted in liquids with indices matching the particle at a wavelength in the visible. The particle and liquid should possess very different dispersion curves for best colours. (05 Aug 1998) |
| optical staining | <microscopy> Producing colour in the microscopical image so as to differentiate one part of the object from another. One way is by use of Rheinberg filters. Another is to use polarized light on an anisotropic specimen. Another important method is by dispersion staining. (05 Aug 1998) |
| auramine O fluorescent stain | <technique> A rapid and accurate technique for Mycobacterium tuberculosis, using auramine O-phenol and a methylene blue counterstain. (05 Mar 2000) |
| green fluorescent protein | <protein> A protein found in jellyfish which fluoresces, or glows green visible light when excited by UV light with a wavelength of 395 nanometres. It can function as a biological marker when attached to other proteins. The structure of the protein is cylindrical with the glowing component, an amino acid complex called a fluorophore, in the middle of it. (09 Oct 1997) |
| microscope, fluorescent | A microscope equipped to examine material that fluoresces under ultraviolet (uv) light. (12 Dec 1998) |
| direct fluorescent antibody | The straightforward detection of antigens using fluorescent labelled antigen-specific antibody. Because detection of the antigen in a substrate of patient sample (cellular smear, fluid or patient-inoculated culture medium) is the goal, direct fluorescent antibody is seldom quantitative. (05 Mar 2000) |
| direct fluorescent antibody test | Test for tissue antigen using either a direct method, by conjugation of antibody with fluorescent dye (fluorescent antibody technique, direct) or an indirect method, by formation of antigen-antibody complex which is then labelled with fluorescein-conjugated anti-immunoglobulin antibody (fluorescent antibody technique, indirect). The tissue is then examined by fluorescence microscopy. (12 Dec 1998) |
| indirect fluorescent antibody | The detection of antibodies to specific antigenic material in the substrate using fluorescent microscopy. Using fluorescent conjugated antibodies which are specific for a particular isotype of antibody, it is possible to distinguish IgG, IgA and IgM isotypes of specific antibodies using indirect fluorescent antibody. This sensitive technique is highly specific in well-trained hands and recent developments in the establishment of internationally recognised standard materials have led to accurate quantitation of antibody concentrations through endpoint titration (the highest serial dilution of specimen at which specific fluorescence remains) and through measuring visual intensity of fluorescence compared to known reference standard material. (05 Mar 2000) |
| Kasten's fluorescent Feulgen stain | <technique> A fluorescent modification of the Feulgen stain, utilizing any one of a variety of fluorescent basic dyes to which SO2 is added; the brilliant fluorescence makes this method unusually sensitive and adaptable to cytofluorometric quantification of DNA. (05 Mar 2000) |