| Gomori's non-specific acid phosphatase stain | <technique> A method in which formalin-fixed frozen sections are incubated in a substrate containing sodium beta-glycerophosphate and lead nitrate at pH 5.0; the insoluble lead phosphate produced is treated with ammonium sulfide to give a black lead sulfide. (05 Mar 2000) |
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| Gomori's non-specific alkaline phosphatase stain | <technique> A calcium-cobalt sulfide method using frozen sections or cold acetone-or formalin-fixed paraffin sections, plus sodium beta-glycerophosphate as a substrate at pH 9.0 to 9.5 with Mg++ as activator; calcium ions precipitate the liberated phosphate, cobalt salt replaces the calcium phosphate, and ammonium sulfide converts the product to a black cobalt sulfide. (05 Mar 2000) |
| Gomori's one-step trichrome stain | <technique> A connective tissue stain that uses haematoxylin and a dye mixture containing chromotrope 2R and light green or aniline blue; muscle fibres appear red, collagen is green (or blue if aniline blue is used), and nuclei are blue to black. (05 Mar 2000) |
| Gomori's silver impregnation stain | <technique> A reliable method for reticulin, as an aid in the diagnosis of neoplasm and early cirrhosis of the liver; the staining solution employs silver nitrate, potassium hydroxide, and ammonia water carefully prepared to avoid having silver precipitate. (05 Mar 2000) |
| Goodpasture's stain | <technique> A stain for Gram-negative bacteria, using aniline fuchsin. (05 Mar 2000) |
| Gordon and Sweet stain | <technique> A stain for reticulin, using acidified potassium permanganate, oxalic acid, iron alum, silver nitrate, formaldehyde, gold chloride, and sodium thiosulfate. (05 Mar 2000) |
| Gram's stain | <microbiology, technique> A method for differential staining of bacteria; smears are fixed by flaming, stained in a solution of crystal violet, treated with iodine solution, rinsed, decolorised, and then counterstained with safranin O. Gram-positive organisms stain purple black and Gram-negative organisms stain pink; useful in bacterial taxonomy and identification, and also in indicating fundamental differences in cell wall structure. (05 Mar 2000) |
| Gram stain | <microbiology, procedure> A method of staining bacteria using a violet stain. The gram staining characteristics (denoted as positive or negative) can assist in the identification of the offending bacteria. A heat fixed bacterial smear is stained with crystal violet (methyl violet), treated with 3% iodine/potassium iodide solution, washed with alcohol and counterstained. The method differentiates bacteria into two main classes, gram-positive and gram-negative. Certain bacteria, notably mycobacteria, that have walls with high lipid content show acid-fast staining the stain resists decolouration in strong acid. (27 Sep 1997) |
| periodic acid Schiff stain | <technique> A histochemical technique based on periodic acid oxidation of a substance containing the 1,2-glycol grouping. It is used for staining carbohydrates as the resulting dialdehyde reacts with Schiff reagent to form a coloured product. Substances that can be demonstrated include carbohydrates, mucins, cartilage matrix, collagen, reticulum, basement membranes, fibrin, thyroid colloid, amyloid, glomerular hyaline deposits, and a number of other secretions or tissue constituents. Also used in for staining gels on which glycoproteins have been run. See: periodic acid Schiff reaction Synonym: PAS stain. (22 Sep 2002) |
| green stain | <technique> A deposit, produced by chromogenic bacteria, found on the cervicolabial portions of the teeth, usually in children. See: acquired pellicle. (05 Mar 2000) |
| Perls' Prussian blue stain | <technique> A stain for ferric iron as in haemosiderins, using potassium ferrocyanide in acetic acid or dilute hydrochloric acid followed by a red counterstain such as safranin O or neutral red; various haemosiderins and most mineral irons give a blue-green reaction, while nuclei stain red. (05 Mar 2000) |
| Gridley's stain | <technique> For fungi, a method for fixed tissue sections based on Bauer's chromic acid leucofuchsin stain with the addition of Gomori's aldehyde fuchsin stain and metanil yellow as counterstains; against a yellow background, hyphae, conidia, yeast capsules, elastin, and mucin appear in different shades of blue to purple. (05 Mar 2000) |
| metachromatic stain | <technique> A stain, such as methylene blue, thionin, or azure A, that has the ability to produce different colours with various histological or cytological structures. (05 Mar 2000) |
| Grocott-Gomori methenamine-silver stain | <technique> A modification of Gomori's methenamine-silver stain for fungi in which sections are pretreated with chromic acid before addition of the methenamine-silver solution and then counterstained with light green to demonstrate black-brown fungi against a pale green background. (05 Mar 2000) |
| peroxidase stain | <technique> A method for demonstrating peroxidase granules in some neutrophils and in eosinophils; the enzyme promotes the oxidation of benzidine by hydrogen peroxide; tissues treated with horseradish peroxidase can also have the enzyme detected in the electron microscope. (05 Mar 2000) |