| 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) |
| methyl green-pyronin stain | <technique> A staining method useful for identification of plasma cells which are intensely pyroninophilic; a mixture of a green and a red dye that has the property of staining highly polymerised nucleic acid (DNA) green and low molecular weight nucleic acids (RNA) red. See: Unna-Pappenheim stain. (05 Mar 2000) |
| Romanovsky type stain | <technique> Composite histological stains including methylene blue, Azure A or B and eosin, sometimes with other stains. Examples are Giemsa, Wright's and Leishman's stain. (18 Nov 1997) |
| Romanowsky's blood stain | <technique> Prototype of the eosin-methylene blue stain's for blood smears, using aqueous solutions made of a mixture of methylene blue (saturated) and eosin. Romanowsky-type stain's depend for their action on compounds formed by interaction of methylene blue and eosin; most are of no value if water is present in the alcohol because neutral dyes become precipitated. (05 Mar 2000) |
| chromate stain | <technique> For lead, a method in which tissues preserved in chromate-containing fixatives, such as Regaud's or Orth's fixatives, precipitate lead as yellow lead chromate crystals; formalin-fixed sections are treated with potassium chromate acidified with acetic acid. (05 Mar 2000) |
| chrome alum haematoxylin-phloxine stain | <technique> A stain used to demonstrate pancreatic islet cells; alpha cells appear red, beta cells blue or unstained. (05 Mar 2000) |
| Roux's stain | <technique> A double stain for diphtheria bacilli which employs crystal violet or dahlia and methyl green. (05 Mar 2000) |
| Ciaccio's stain | <technique> A method for demonstrating complex insoluble intra-cellular lipids using fixation in a formalin-dichromate solution, embedding in paraffin, staining with Sudan III or IV, and examination in aqueous mountant. (05 Mar 2000) |