| Gomori's aldehyde fuchsin stain | <technique> A stain used to demonstrate beta cells of the pancreas, storage form of thyrotrophic hormone in beta cells of the anterior pituitary, hypophyseal neurosecretory substance, mast cells, granules, elastic fibres, sulfated mucins, and gastric chief cells. (05 Mar 2000) |
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| Gomori's chrome alum haematoxylin-phloxine stain | <technique> A technique used to demonstrate cytoplasmic granules, after Bouin's or formalin-Zenker fixatives, using oxidised haematoxylin plus phloxine; in the pancreas, beta cells are blue, alpha and delta cells are red, and zymogen granules are red to unstained; in the pituitary, alpha cells are pink, beta cells and chromophobes are gray-blue, and nuclei are purple to blue. (05 Mar 2000) |
| Gomori's methenamine-silver stain | <technique> Techniques for 1) argentaffin cells: a method using a methenamine-silver solution in combination with gold chloride, sodium thiosulphate, and safranin O; argentaffin granules appear brown-black against a green background; 2) urates: warm sections are treated directly with a hot methenamine-silver solution to produce a blackening of urates; 3) fungi: see Grocott-Gomori methenamine-silver stain; 4) melanin, which reduces silver nitrate. (05 Mar 2000) |
| 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) |
| 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) |