Table of contents :

• challenging
• fixation
• staining
• vital stainings
• von-vital stainings
• aims of histochemistry

• cytoscopy : examination of cells
• specimen : 1. a sample or part of a thing, or of several things, taken to show or to determine the character of the whole, as a specimen of urine.  2. a preparation of tissue for pathological examination or of a normal tissue, organ, or organism for study of its structure.
• corrosion specimen : a preparation of an organ, such as the liver, by injection of certain of its structures, as the arteries and veins, and chemical digestion of surrounding substance.
• microincineration : the incineration of minute specimens of tissue or other substance, for identification from the ash of the elements composing it.
• cytology : the study of cells, their origin, structure, function, and pathology.
• aspiration biopsy cytology (ABC) : the microscopic study of cells obtained from superficial or internal lesions by suction through a fine needle.
• exfoliative cytology : microscopic examination of cells desquamated from a body surface or lesion as a means of detecting malignancy to measure hormonal levels, etc. Such cells may be obtained by such procedures as aspiration, washing, smear, and scraping, and the technique may be applied to vaginal secretions, sputum, urine, abdominal fluid, prostatic secretion, etc.
• helminths
• Baermann test (for extraction of soil nematodes from earth and detecting larvae of Strongyloides stercoralis in feces): a specimen of soil or feces is suspended over gauze or wire mesh in a water-filled funnel to which a piece of rubber tubing is attached; larval nematodes migrate from the specimen to the water, and collect in the rubber tubing.
• hatching test : a test for the detection of live schistosome eggs in urine or feces, dependent upon the eggs hatching to produce miracidia when placed in water; the miracidia are attracted to light and can readily be identified
• Stoll test : a technique for the quantitative estimation of the worm burden of an individual based on collection of a 24-hour stool specimen and counting the number of ova present in an aliquot
• Kato test : a technique for the quantitative estimation of the worm burden of an individual, based on estimation of a standard 50-mg sample of fresh feces cleared with glycerine.
• microtome : an instrument for cutting thin slices of tissue for microscopical study.
• freezing microtome : a microtome for cutting frozen sections.
• cryostat : in pathology and histology, a chamber containing a microtome for sectioning frozen tissue.
• rocking microtome : a microtome in which the specimen is held in the end of a lever which passes up and down over a stationary knife.
• rotary microtome : one in which a wheel action is translated into a back-and-forth movement of the specimen being sectioned.
• sliding microtome : one in which the specimen being sectioned is made to slide on a tract.
microtomy / histotomy : the cutting of thin sections
• clearing
• K⁺OH^- 10% for hair and nail samples
• challenging
• Itano-Pauling sickling test : a method for demonstrating hemoglobin S and sickling in erythrocytes, particularly in the heterozygous state, by reducing the environmental oxygen around them. It may be done by simply sealing a drop of blood under a coverslip or may be speeded up by adding 2% sodium metabisulfite or sodium dithionite to the preparation.
• heat stability : unstable hemoglobins precipitate
• isopropanol precipitation test : a drop of blood is mixed with 17% the nonpolar solvent isopropanol at 37 °C; most unstable hemoglobins precipitate more readily than other hemoglobins. Addition of potassium cyanide reduces false-positive results.
• Heinz bodies formation test : after acetylphenylhydrazine exposure
• sucrose hemolysis test : the patient's whole blood is mixed with isotonic sucrose solution, which promotes binding of complement to red cells, then incubated and examined for hemolysis; hemolysis > 10% is indicative of paroxysmal nocturnal hemoglobinuria.
• Ham's acidified serum test : the patient's washed red cells are incubated at 37°C in acidified normal serum or the patient's acidified serum; after centrifugation the supernatant is examined colorimetrically for hemolysis. In paroxysmal nocturnal hemoglobinuria the red cells are abnormally susceptible to lysis by complement, which is activated by the alternate pathway in acidified serum
• autohemolysis test : a sample of blood is defibrinated and incubated at 37°C for 24 and 48 hours; if hereditary spherocytosis is present, spontaneous hemolysis is increased
• osmotic fragility test : heparinized or defibrinated blood is placed in tubes of sodium chloride solution (pH 7.4) varying in concentration from 0.85 to 0.00% (w/v); the amount of hemolysis in each tube is determined colorimetrically. Increased fragility indicates spherocytosis.
• Donath-Landsteiner test : a test based on the fact that the blood of patients with paroxysmal cold hemoglobinuria contains complement-dependent iso- and autohemolysin (Donath-Landsteiner antibody) which unites with red cells only at low temperatures (2° to 10°C), hemolysis occurring only after warming to 37°C.
• fixation : the use of a fixative to preserve histological or cytological specimens. A fixative is a fluid, often a mixture of several reactive chemicals, into which histological or cytological specimens are placed so that, by processes such as denaturation and cross-linking of proteins, autolysis is prevented, the specimen is hardened to withstand further processing, and the specimen is preserved in a close facsimile of the living state in regard to both cellular morphology and the location of subcellular constituents. A standard fixative for routine use is buffered neutral formalin. A wide variety of fixatives, containing ingredients such as formalin, glutaraldehyde, and other aldehydes, ethanol, methanol, and other alcohols, acetone, acetic acid, chromates, mercuric salts, and picric acid, are used for special purposes.
• heat fixation
• methanol fixation
• ethyl alcohol / ethanol: among the earliest fixing solutions used by histologists, it is not frequently used as a primary fixative except in Best's carmine method, periodic acid-Schiff reaction, and Ranson's method. Alcohol (70 to 100%) is valuable for the preservation of the cellular polysaccharide glycogen for routine lightmicroscopic study. Alcohol fixation can produce distortions and shrinkage unless used at a low temperature.
• formalin : a 37% solution of formaldehyde. Formaldehyde is a gas soluble to about 55% in water. Solutions used as fixatives are prepared in terms of the percentage of formalin, not formaldehyde. The commonly used 10% formalin (formol) is 10 ml of formalin and 90 ml of water. Formalin is also used with other reagents (as in Helley's, Bouin's, and Regaud's fluids). Because formalin is a strong reducing agent, it is mixed with other ingredients only immediately before use.
• formic acid : a recommended fixative for Ranvier's gold chloride method, as a substitute for undiluted fresh lemon juice.
• Kaiserling's fixative or solution
• Zenker's fixative, fluid or solution : a fixative solution containing corrosive mercuric bichloride, potassium bichromate, sodium sulfate, glacial acetic acid, and water; the sodium sulfate is frequently omitted. A mercury precipitate is left in the tissues and is troublesome to the inexperienced microscopist unless removed by an iodine solution. The most widely used variations of this fixative are the modifications by Maximow, by Helly, and by Custer, in which formalin replaces the acetic acid.
• Maximow's fixative : a solution composed of Zenker's fixative, formol, and osmic acid, used in preserving vertebrate cells for study with the visible light microscope
• Helly's fluid / Zenker-formol fixative / formol-Zenker solution : a histologic fixative consisting of Zenker's fluid in which the glacial acetic acid is replaced by formalin. The concentration of formalin used varies between 5 and 10% : the most widely used formula consists of 9 parts Zenker stock solution and 1 part neutral formalin (Zenker-Helly-Maximow). This is an excellent cytological and tissue fixative.
• Bovin fixation : an acetic fixation which destroys the mitochondria of the cell.
• Rossman's fluid : a fixative capable of preserving cellular glycogen. This fixative consists of absolute ethyl alcohol (90 ml) saturated with picric acid (approximately 9%) and neutral formalin (10 ml). After overnight fixation, the excess picric acid is removed by rinsing in 95% alcohol for several days.
• Altmann's fluid : a histologic fixing fluid composed of equal parts of 2% osmic acid solution and a 5% potassium dichromate solution
• Bouin's fluid : a histologic fixing fluid consisting of formaldehyde solution (25 ml), glacial acetic acid (5 ml), and saturated solution of trinitrophenol (picric acid) (75 ml). Almost any stain can be used after fixation in Bouin's. The picric acid also enhances cellular and tissue staining reactions. This fixative was described by Bouin in 1897.
• Delafield's fluid : a fixing fluid for delicate histologic tissues, containing osmic acid, chromic acid, acetic acid, and alcohol
• Tellyesniczky's fluid : a fixing solution consisting of potassium dichromate, water, and glacial acetic acid.
• Carnoy's solution : an acid fixative used for studying the cell nucleus and chromosomes, composed of: 3 parts absolute ethanol, 5 parts saturated picric acid, 5 parts 40% formaldehyde (formalin), and 1 part glacial acetic acid.
• van Gehuchten's fluid : a modified mixture of Carnoy's fluid containing absolute alcohol, chloroform, and glacial acetic acid. A very fast-acting fixative.
• Gilson's solution : a fixative solution consisting of mercury bichloride, nitric acid, glacial acetic acid, 70% alcohol, and water.
• Kaiserling's solution :
• 1. for fixation: formalin 400 mL, water 2000 mL, potassium nitrate 30 g, potassium acetate 60 g.
• 2. for restoring color: alcohol 80%.
• 3. for preservation: potassium acetate 200 g, glycerol 400 mL, sodium arsenate 100 g, water 2000 mL.
• Perenyi's solution : an embryological fixing solution, consisting of 10% solution of nitric acid, alcohol, and 0.5% solution of chromic acid.
• Carrel-Dakin fluid : diluted sodium hypochlorite solution.
• decalcifying fluid : a solution of formic acid and formalin.
• Heidenhain's susa fixative or solution : a decalcifying solution that derives its name from the initial letters of sublimate (mercury bichloride saturated in 0.6% NaCl) and saure (trichloroacetic and glacial acetic acid), key ingredients of the fixative together with formalin, all in aqueous solution. It is considered a good general- purpose fixative, with rapid penetration.
• Thoma's fluid : a decalcifying fluid for histologic work, consisting of alcohol and pure nitric acid.
• Waldeyer's chlorpalladium fluid : a decalcifying fluid for anatomical and other specimens, containing palladium chloride and hydrochloric acid
• hardening fluid
• Lang's fluid : a hardening fluid containing corrosive mercuric chloride, sodium chloride, and acetic acid, in water
• Müller's fluid : a hardening solution consisting of potassium dichromate (2.0 to 2.5%), sodium sulfate (1%), and distilled water. Formerly, this was much used for prolonged fixation and mordanting of nervous tissue. It has now been largely replaced by Orth's fluid, which is composed of potassium clichromate (2.0 to 2.5%) and formalin (10%) in distilled water. The sodium sulfate is omitted. Fixatives of this type do not store well and must be prepared immediately before use.
• formol-Müller fluid : Müller's fluid to which formaldehyde has been added.
• Parker's fluid : a hardening fluid composed of formaldehyde and alcohol
• Schaudinn's fluid : a hardening fluid consisting of mercury bichloride, alcohol, and distilled water.
Standard fixatives for processing specimens for electron microscopy.
• glutaraldehyde fixative : a fixative used in specimen preparation for electron microscopy that does not simultaneously stain the tissue. This 5-carbon dialdehyde of relatively simple structure is the most commonly used fixative in electron microscopy, and it is becoming increasingly useful for light microscopy of thin sections of plasticembedded tissues. It gives superb images of cellular structure and can be used as a fixative in histochemical enzyme localization by light and electron microscopy. It is used as a 1 to 6.5% solution in isotonic buffer at 1 to 4°C. Glutaraldehyde and osmium tetroxide are considered the finest fixatives available to the histologist. One of the advantages of glutaraldehyde compared with osmium is that it does not "stain" or alter the staining characteristics of the tissue during fixation. Glutaraldehyde and osmium tetroxide are sequentially used, in that order, in preparing tissue for electron microscopy. 1-mm sections of plastic-embedded tissue permit very high resolution light microscopy. Ultrathin sections of the same material can also be used for electron microscopy.
• osmium tetroxide (OsO₄) : commonly but incorrectly referred to as osmic acid, this is considered an excellent fixative for most cytological morphology. It is used either as a primary fixative or secondarily after aldehyde fixation. it cannot be used for histochemical studies. Osmium blackens lipids and stains the Golgi apparatus in light microscopic preparations. A severe limitation of osmium-fixed material is that most routine and special stains cannot be used. Its primary use is in electron microscopy
• Tokuyasu cryosectioning technique : an immunoEM procedure in which cells are chemically fixed and infiltrated with cryoprotectant before they are frozen by being plungede into liquid nitrogen. Sectioning is carried out at low temperature, after which the frozen sections are transferred to room temperature, thawed, subjected to immunolabeling and, only then, embedded in a thin layer of support and contrasting film.
• cryofixation : the rapid freezing of small samples such that cellular components can be immobilized in milliseconds
• high-pressure freezing : a cryofixation procedure that uses high pressure to freeze samples efficiently and to minimize the formation of damaging ice crystals
• squash technique : a method of preparing cells for chromosome study, suspending them in hypotonic solution, then incubating them and exposing them to colchicine for one hour; after fixing and staining, a drop of the stained material is placed on a glass slide and covered with a glass slip, which is then pressed against the slide with one thumb
• Wickersheimer's fluid : a fluid composed of arsenic trioxide, sodium chloride, and the sulfate, carbonate, and nitrate of potassium in a mixture of water, alcohol, and glycerin; used for preserving anatomical specimens.
• Drabkin's solution : an aqueous solution containing 1.0 g sodium bicarbonate, 0.05 g potassium cyanide, and 0.20 g potassium ferricyanide per liter; used to lyse red cells and convert hemoglobin to cyanmethemoglobin in hemoglobinometry.
• Farrant's solution : a mounting preparation used in bacteriological work, containing glycerin, water, arsenious acid solution, and gum arabic.
• Fehling's solution : an alkaline copper sulfate solution similar to Benedict's reagent.
• reagent : a substance employed to produce a chemical reaction so as to detect, measure, produce, etc., other substances.
• amino-acid reagent : a 0.5% solution of sodium b-naphthoquinone-4-sulfonate freshly prepared.
• Benedict's reagent : any of several alkaline copper sulfate solutions used for Benedict's test for glucose.
• Berthelot's reagent : an alkaline solution of phenol and hypochlorite, used in the Berthelot reaction.
• Bial's reagent : orcinol 1.5 g, fuming hydrochloric acid 500 g, ferric chloride (10%) 20–30 drops.
• biuret reagent : any of various alkaline copper sulfate solutions containing a variety of stabilizers, used in the biuret reaction
• Bogg's reagent : dissolve 25 g of phosphotungstic acid in 125 mL of water. Dilute 25 mL of concentrated hydrochloric acid to 100 mL. Mix the 2 solutions.
• diazo reagent : a reagent consisting of 2 solutions which are mixed just prior to the test in the proportion of 25 mL of solution A to 0.75 mL of B. Solution A: sulfanilic acid, 1 g; distilled water, 1000 mL. Solution B: sodium nitrite, 0.5 g: distilled water, 100 mL.
• Ehrlich's diazo reagent : Solution A: dissolve 5 g of sodium nitrite in 1 L of distilled water. Solution B: dissolve 5 g of sulfanilic acid and 50 mL of hydrochloric acid in 1 L of distilled water. For use mix 1 part of A with 50 to 100 parts of B.
• Ehrlich's aldehyde reagent : 4 g of paradimethylaminobenzaldehyde in a mixture of 80 mL of concentrated hydrochloric acid and 380 mL of ethyl alcohol.
• Fouchet's reagent : 1.0 g ferric chloride and 25.0 g trichloroacetic acid dissolved in water to make 100 mL
• general reagent : a reagent that indicates the general class of bodies to which a substance belongs.
• Grignard's reagent : any of several compounds of magnesium with an organic radical and a halogen; these reagents undergo reactions with many substances producing important products.
• Lloyd's reagent : an especially fine preparation of fuller's earth obtained by elutriation; used to absorb alkaloids from solutions.
• Mörner's reagent : a solution of 1 volume of formalin, 45 volumes of distilled water, 55 volumes of concentrated sulfuric acid; used as a test for tyrosine
• Nessler's reagent : an aqueous solution of 5% of potassium iodide, 2.5 per cent of mercury bichloride, and 16% of potassium hydroxide; used as a test for ammonia.
• Rosenthaler's reagent / arsenic–sulfuric acid reagent (for alkaloids) : 1 part of potassium arsenate in 100 parts of concentrated sulfuric acid.
• Schiff's reagent / leukofuchsin : a reagent for testing for the presence of aldehydes, prepared by dissolving 0.25 g of basic fuchsin in 1 liter of water and decolorizing by passing sulfur dioxide (sulfurous acid) into it. In the presence of aldehyde the blue color is restored.
• Scott-Wilson reagent : add 90 g sodium hydroxide in solution to 5 g mercuric cyanide in solution, then add 1.45 g silver nitrate solution with constant stirring.
• Flemming's solution : a solution for hardening histological specimens, consisting of chromium trioxide, osmium tetroxide, glacial acetic acid, and water.
• Hamdi's solution : a solution for preserving histological specimens, consisting of sodium sulfate, salt, glycerin, and water.
• Schällibaum's solution : a solution of celloidin and oil of cloves used in histological work to attach paraffin sections to slides.
• staining : the artificial coloration of a substance, such as the introduction or application of material to facilitate examination of tissues, microorganisms, or other cells under the microscope
• in tela : in tissue; relating especially to stained histological preparations
• overstain : to stain a tissue excessively, so that certain elements may be properly stained when the excess of stain is washed out.
• automated staining :
• Eridan staining system (source : DakoCytomation of Carpinteria, Calif) : a benchtop instrument that automates slide preparation. Eridan has 8 drawers and a 64-slide capacity. While one drawer of slides is analyzed, the next set of slides is prepared using InfoGlyph, a computer-generated dot-matrix patterning system that would replace bar codes. By the time the user loads the last drawer, the first drawer is ready to be reloaded, thereby avoiding workflow gaps inherent in batch processing. The Eridan system can process several hundred slides in an eight-hour shift instead of the usual 50-100 slides. In an 80-90-minute one-drawer run, the instrument deparaffinizes the slides, unmasks antigens with warm buffer, and stains antigens of interest brown by exposing the tissues to the appropriate primary antibody, a secondary antibody coupled to horseradish peroxidase, and a colorimetric visualization reagent. Test results flow back into the hospital's local-area network, making information management much easier, more accurate, and more cost-effective. Although the Eridan system is compatible with any vendor's reagents, its computer can automatically reorder those from DakoCytomation using a dedicated phone line. (The system connects to the hospital's LAN to facilitate sharing of confidential data but uses a phone line to connect with external sites to avoid firewall problems.) The company also uses this line to query the instrument and suggest solutions to technical problems. Before making the system commercially available, however, DakoCytomation extensively tested the software and mechanical parts, using temperature-controlled humidity chambers to ensure the instrument would perform well in environments ranging from the steamy jungles of Brazil to the frigid winters of northern Sweden. There is no evidence that the antigen retrieval or deparaffinization results in tissue loss.
• acid stain : a stain which is acid in reaction and more readily colors the protoplasm of cells.
• eosin / water-soluble eosin / eosin W or W S / yellowish eosin / eosin Y : a rose-colored stain or dye: typically the sodium salt of tetrabromofluorescein, C₂₀H₆Br₄Na₂O₅, C.I. 45380. Commercially, several other red coal tar dyes are called eosin. All the eosins are bromine derivatives of fluorescin. Eosin is an important plasma stain, used especially with hematoxylin, methylene blue, and methyl green.
• eosin B / eosin I bluish : dibromodinitrofluorescein, a dye having staining properties similar to eosin, but of a distinctly bluer shade.
• ethyl eosin : the ethyl ester of eosin.
• basic stain : stain which is basic in reaction and shows an affinity for the nuclei of cells.
• basic fuchsin stain : a stain containing basic fuchsin in distilled water
• neutral stain : a combination of an acid and a basic stain for staining neutrophil tissues
• lipoid stain : a stain made from any fatlike, or lipid, substance e.g., Sudan III
• metachromatic stain / methachromasia : a stain that colors certain cell constituents a color different from that of the stain itself
• toluidine blue
• methyl violet
• pseudoisocyanin
• nuclear stain : a stain which has a special affinity for the nuclei of cells
• hematoxylin : a colorless crystalline compound obtained by extracting logwood (Haematoxylon (Haematoxylum) campechianum) with ether. It may be used as an indicator with a pH range of 5–6, but is mainly used in oxidized form as a stain in microscopy.
• Delafield's hematoxylin : a preparation of hematoxylin, alcohol, ammonia alum, water, glycerin, and methanol
• Ehrlich's acid hematoxylin : a preparation of hematoxylin
• Harris' hematoxylin
• alum hematoxylin / hemalum : a mixture of hematoxylin and alum introduced by Mayer, widely used as a nuclear stain, especially in combination with eosin as a general oversight method. Also, any alum and hematoxylin stain
• hemalum stain : hematoxylin and alum, widely used, especially in combination with eosin
• iron hematoxylin : see iron hematoxylin method, Heidenhain's iron hematoxylin stain, and Weigert's iron hematoxylin stain
• plasmatic or plasmic stain : a stain which colors the tissue uniformly throughout.
• protoplasmic stain : a stain which has a special affinity for the protoplasm of cells
• dye : any of various colored substances that contain auxochromes and thus are capable of coloring substances to which they are applied; used for staining and coloring, as test reagents, and as therapeutic agents in medicine.
• acid, acidic or anionic dye : one which is acidic in reaction and usually unites with positively charged ions of the material acted upon
• basic or cationic dye : one which is basic in reaction and unites with negatively charged ions of material acted upon
• amphoteric dye : one containing both reactive basic and reactive acidic groups, and staining both acidic and basic elements.
• azo dye : any of a large group of synthetic dyes whose chromophore group is the structure —N=N—
• metachromatic dye : a dye that stains tissues two or more colors.
• orthochromatic dye : a dye that stains tissues a single color.
• selective stain : a stain which has a special affinity for a certain tissue element, staining it more vividly than, or to the exclusion of, other elements of the same specimen.
• aceto-orcein method : a staining method for sex chromatin bodies in smears of oral mucosa. This technique has 2 advantages over other methods for nuclear sexing: both the smear and dye are easy to prepare, and the method is just as accurate as other methods but much more rapid. Nuclei stain reddish purple
• acetylcholinesterase histochemical method (Seligman) : a method useful for demonstrating enzymatic activity by light and electron microscopy using osmiophilic organic compounds as substrates. Enzyme sites appear black
• Best's carmine stain : a stain for demonstrating glycogen. The rationale for this stain for glycogen is unknown. The carmine is used in an aqueous solution with potassium carbonate and potassium chloride. Glycogen stains bright red. A nuclear stain such as hernatoxylin is commonly used with Best's carmine. The periodic acid-Schiff reaction is another stain for glycogen and other polysaccharides
• Ciaccio's stain : a stain for demonstrating lipids
• gallocyanin stain : this method was popularized by Einarson in 1932. It utilizes a basic oxazine dye (gallocyanin) in combination with chrome alum. It was considered by some to be a specific stain for nucleic acids. Nuclear DNA and RNA and cytoplasmic RNA stain blue. Acidic mucopolysaccharides may also be stained. Compared with other basic dyes, gallocyanin binds strongly with nucleic acids
• Gomori-Takamatsu stains : stains used for histological demonstration of enzymes, especially phosphatases and lipases in sections; also methods for demonstration of connective tissue fibers and secretion granules
• Goodpasture's stain : a method for demonstrating the peroxidase reaction
• Hale's iron stain : a stain used on substances with a high acid polysaccharide content because of the ability of polyanionic polysaccharides to bind polyvalent cations. Its main component is colloidal iron (Fe³⁺).
• Kopsch's method : this is one of several methods used to demonstrate the Golgi apparatus. Small pieces of tissue are immersed in 2% osmic acid for 8 to 16 days. The Golgi apparatus stains black. If stained, mitochondria and ground substance appear reddish brown. Several modifications of this method have been developed
• luxol fast blue-PAS method : this method, utilizing luxol fast blue, has become popular for staining myelin, because it can be used with other stains, allowing combinations that are not possible with the older hernatoxylin methods. Myelin nerve sheaths stain blue-green. PAS-positive substances stain pink to violet. The method consists of staining in 0.1% alcoholic solution of luxol fast blue, differentiation in lithium carbonate, and counterstaining with periodic acid-Schiff reaction. The method was introduced by Klüver and Barrera in 1953.
• Mayer's mucihematein : a specific stain for mucin
• Ehrlich's neutral stain : a mixture of methylene blue and acid fuchsin, used to stain blood corpuscles.
• Glees' method : this silver method was developed by Glees in 1946 for the study of normal and degenerating synaptic boutons. It also demonstrates neurofibrils. Although Glees' method has produced valuable results in the hands of experienced investigators, it has not come into general use. One reason for this is that this method has so far been effective only in certain regions of the central nervous system. A factor limiting its usefulness is the concomitant impregnation of normal axons and axon terminals, which obscure degenerating axons and terminals. Nerve fibers appear black
• methylene blue and erythrocin : this is a frequently used combination to stain tissues. Methylene blue stains basophilic constituents of the tissue, whereas erythrocin stains the acidophilic elements.
• methyl green-pyronin stain : a solution of methyl green and pyronin (usually pyronin Y) used as a differential stain for DNA and RNA: DNA is stained blue-green by methyl green and RNA is stained red by pyronin.
• Pappenheim's stain : the original methyl green–pyronin staining method, used to differentiate between basophilic granules of erythrocytes and nuclear fragments.
• Unna-Pappenheim stain : a variation of methyl green–pyronin stain, used to detect plasma cells and demonstrate nucleoproteins.
• Nassar-Shanklin silver diaminohydroxide method : a good silver method for staining neuroglia in formalin sections. Formalin-fixed paraffin sections are impregnated with silver diaminohydroxide or with strong Hortega silver carbonate dissolved with strong ammonia after sensitizing with sodium sulfite. Microglia, oligodendroglia, and fibrous and protoplasmic astrocytes can be successfully impregnated by this method. Sensitization with sodium sulfite is essential for good results
• Pinkus' acid orcein-Giemsa method : this is a modification of the original Unna-Taenzer procedure by Pinkus in 1944, which has been further modified and simplified by Pinkus and Hunter. A good method to demonstrate connective tissue elements. Material is fixed in 10% formalin, formol-alcohol, or absolute alcohol. Paraffin sections are used. Nuclei stain deep blue; cytoplasm, light blue; collagen, rose pink; and elastic fibers, dark brown
• Ranvier's gold chloride method (1880) : it demonstrates nerve endings in muscle. Nerve fibers are variably stained red to purple-black. The tissue is fixed in formic acid or undiluted fresh lemon juice before immersion in an aqueous solution of gold chloride
• Unna's alkaline methylene blue : a strongly alkaline solution of methylene blue which is valuable for staining plasma cells.
• Verhoeff's stain : a stain for demonstrating elastic tissue
• Verhoeff-van Gieson stain : a good histopathological stain for demonstrating elastic fiber. It consists of staining by acid fuchsin and picric acid. The stain fades in time and is therefore not used as frequently as the Mallory connective tissue stain. Collagen stains bright red; muscle and cytoplasm, yellow; and nuclei, blue to black. Delicate collagen fibrils and reticulum stain very faintly or not at all. It is valuable as a counterstain in techniques that stain elastic fibers a contrasting color (e.g., the methods of Verhoeff and Weigert). Combined with Verhoeff's stain, it is one of the most valuable stains for the study of blood vessels.
• von Kossa's method or stain for calcium deposits (including Michaelis-Gutmann bodies) : the high silver nitrate concentration in the classical method was replaced by 0.05% silver lactate with hydroquinone remaining the reducing agent of choice. The present modification stained calcification nodules with a sensitivity comparable to the original von Kossa reaction, but resulted in a reduced background staining in cultured osteoblasts. The method works well also with plastic- or paraffin-embedded tissue sections.
• Weigert's fibrin stain : a method, many variations of which have been used in both fixation and staining; stains gram-positive bacteria as well as fibrin
• Weigert's myelin sheath method : described by Weigert in 1885 for demonstrating the myelin sheath of normal nerve cell processes. It is used principally on formol-fixed tissue of the central nervous system to demonstrate fiber tracts and to show the arrangement of gray and white matter. The basic procedure requires the use of a mordant, potassium dichromate, a hematoxylin stain, and a differentiating fluid. Normal but not degenerating or degenerated myelin sheaths stain black
• Weigert's neuroglia fiber stain : a complicated method for demonstrating fibrous glia, which works best on human material
• Weigert's resorcin-fuchsin stain : an excellent method for the demonstration of elastic fibers. The procedure consists of staining with a ferric chloride-hematoxylin mixture. Several counterstains may be used. Elastic fibers stain blue-black to black. Other tissue elements depend upon the counterstain used. Commonly used counterstains are phloxine B or van Gieson's.
• Weil's method or stain : Weil's hematoxylin method for staining myelin sheaths does not depend upon a specific method of fixation, although morclanting of formalin-fixed material by Weigert's potassium dichromate and chromium fluoride is advisable. The stain is composed of equal parts of iron alum (4%) and hernatoxylin (1%). Myelin sheaths stain black or dark gray.
• Wilder's method : this is a silver impregnation method for reticular fibers. Reticular fibers stain black; collagen, rose color; and other tissue elements depend upon the counterstain used
• pyronin / pyronine : any of several basic xanthene dyes ranging from pink-red to purple-red in color, used as histological stains and as specific stains for RNA
• pyronin B : a basic xanthene dye used as a stain for bacteria, molds, and RNA.
• pyronin G or Y : a basic xanthene dye used as a bacterial stain and as the RNA-staining component of methyl green–pyronin stain
• red : a red dye or stain.
• alizarin red S / alizarin water-soluble red / sodium alizarinsulfonate : a yellow-brown or orange-yellow powder used as a stain in microscopy, as a reagent for aluminum, as an acid-base indicator, and in the determination of fluorine
• alizarin red : the sodium salt of alizarin monosulfonate
• fuchsin [from the pink, red, or purple flower fuchsia, after Leonard Fuchs, German botanist, 1501–1566] : any of several red to purple triaminotriphenylmethane dyes.
• acid fuchsin or magenta : a mixture of sulfonated fuchsins used in Andrade's indicator and in various complex stains
• basic fuchsin or magenta / magenta / aniline red : a triphenylmethane dye, a mixture of
• pararosaniline / magenta 0 : a basic dye occurring as colorless to red crystals, the chief constituent of basic fuchsin
• basic red 9 / rosaniline / magenta I : a basic dye derived from triphenylmethane, occurring as reddish brown crystals, which is soluble in acids and alcohol and slightly soluble in water. It is used, usually as the hydrochloride, in the preparation of other dyes and as a component of basic fuchsin.
• magenta II : triaminoditoylphenylmethane chloride, a component of basic fuchsin
Used in the form of carbolfuchsin in the Gram and Ziehl-Neelsen stains, as an antifungal agent in Castellani's paint, as a germicide, and as a histologic stain
• new fuchsin / magenta III : a basic dye with staining properties much like those of basic fuchsin; it is a tricyclic compound, trimethyl fuchsin
• basic red 2 / cotton red / safranin or safranine O : a basic red aniline dye used as a nuclear stain and as a counterstain in Gram's method
• bordeaux red / fast red B or P / cerasine : a red azo dye, used as a cytoplasmic stain
• bromphenol or bromophenol red : an indicator, dibromphenolsulfonphthalein, used in determining hydrogen ion concentration, being yellow at pH 5.2 and red at pH 6.8
• carmine red : a stain derived from carmine.
• Sudan : a group of azo compounds used as stains for fats.
• Sudan I : a yellow fat-soluble azo dye, chemical name 1-phenylazo-2-naphthol; it is an irritant and suspected carcinogen.
• Sudan II : an orange fat-soluble azo dye, chemical name 1-[2,4&-xylylazo]-2-naphthol used in biological staining of fats; it is an irritant and suspected carcinogen.
• Sudan III / cerasine, oil or tony red / Sudan G : chemical name: 1-(p-phenylazophenylazo)-2-naphthol. A red fat-soluble azo dye; an important stain for the demonstration of neutral fats.
• Sudan IV / scarlet red / oil red IV / ponceau 3B / scarlet R / scharlach R : a red fat-soluble azo dye, used as a biological stain for fats; it has some power to stimulate the proliferation of cells, and has been used to enhance wound healing
• Sudan black B / fat black HB / solvent black 3 : a black, fat-soluble diazo dye, used as a stain for fats.
• Sudan yellow G : a brown powder used as a stain for fats.
• chlorophenol red : a pH indicator with a range of 5.2 (yellow) to 6.8 (red).
• Congo red / cotton red B or C / direct red : an odorless, dark red or reddish brown powder which decomposes on exposure to acid fumes. It is used as a diagnostic aid in amyloidosis, and has been used as an antihemolytic and detoxicant


• benzopurpurine : any one of a series of azo-dyes of a scarlet color, used especially as a contrast stain with hematoxylin and other blue stains.
• dianil red 4 C or 4 B / direct red 4 B / cotton red 4 B / benzopurpurine 4 B : a compound used as an analytical reagent, as a biological stain, and as an indicator with a pH range of 1.2 (violet) to 4.0 (red)
• cresol red : an indicator, o-cresol-sulfonphthalein, used in the determination of the hydrogen ion concentration. It has a pH range of 7.2 to 8.8, being yellow at 7.2 and red at 8.8.
• indigo or indoxyl red : a coloring matter produced by heating an aqueous solution of indoxyl to 130°C.
• magdala or naphthaline red / Sudan red : a basic dye used for staining connective tissue. It is a mixture of monoamino- and diamino-naphthosafranins.
• methyl red : a dye, used as an indicator in the determination of hydrogen ion concentration; it has a pH range of 4.4 to 6, being red at 4.4 and yellow at 6.
• neutral or toluylene red : a basic red fluorochrome dye used as a pH indicator with a range of 6.8 (red) to 8 (yellow) and as an important supravital stain for the demonstration of vacuoles in blood cells, and especially of the vacuome
• oil red O : a red diazo dye that is more soluble in fat than in water or alcohols; used as a stain for neutral fats.
• phenol red / phenolsulfonphthalein (PSP) : a bright to dark red, crystalline powder administered by intramuscular or intravenous injection as a test of renal function and as a qualitative test for residual bladder urine
• provisional red : a colored lipin obtained from rhodopsin.
• scarlet red sulfonate : the sodium salt of azo-benzene-disulfonic acid azobeta-naphthol; used for the same purpose as scarlet red.
• senitol red : a dye with a highly selective germicidal action on staphylococci; it is also used to sensitize photographic plates to red rays of light.
• trypan red : an acid azo dye used as a vital stain and which possesses some trypanocidal activity.
• vital red : a dye which is introduced directly into the circulation by venipuncture for the purpose of estimating the volume of the blood in the body by determining the concentration of the dye in the blood plasma
• phloxine B : a red acid dye used as a plasma stain in histology and as a component of Mallory's phloxine–methylene blue stain
• yellow : a dye or stain that produces a yellow color.
• alizarin yellow : an indicator used in the determination of hydrogen ion concentration with a pH range of 10.1–12.1.
• brilliant yellow : an indicator used in determining hydrogen ion concentration, with a pH range of 6–8.
• butter or methyl yellow / p-dimethylaminoazobenzene : a dicyclic carcinogenic compound used as an indicator in tests for and in Ehrlich's aldehyde reaction to detect urobilinogen. It has a pH range of 2.9 to 4, being red at 2.9 and yellow at 4
• corallin / aurin : a triphenylmethane derivative occurring as deep red masses with a greenish metallic luster; used as an indicator and dye intermediate
• corallin yellow / yellow corallin : the sodium salt of aurin, occurring as yellow masses with a greenish metallic luster, which turns red in solution
• acid or fast yellow : a yellow, acid azo dye, used in staining bone.
• imperial yellow / aurantia : an orange coal tar stain, the ammonium salt of hexanitrodiphenylamine; used in staining mitochondria
• Manchester, Martius or naphthol yellow : a poisonous, yellow, azo dye used as a stain and in the preparation of light filters
• metanil or metaniline yellow (extra) : an indicator used in the determination of hydrogen ion concentration, with a pH range of 1.2–2.3.
• Philadelphia yellow / phosphine : coal tar dye extremely destructive to infusorial life; it is used as a stain
• green : a green coloring matter or dye.
• acid green : any of several green acid dyes, generally light green SF
• light green SF yellowish / light green, 2 G or 2 GN / fast acid green N : an acid dye used as a plasma stain.
• brilliant, methyl or ethyl green / malachite green G : a basic dye having powerful bacteriostatic properties for gram-positive organisms.
• bromcresol or bromocresol green : an indicator, tetrabromo-m-cresolsulfonphthalein, used in the determination of hydrogen ion concentration, being yellow at pH 4.0 and blue at pH 5.4
• fast green FCF : a green acid dye used as a histologic stain for plasma and collagen.
• indocyanine green : a tricarbocyanine dye occurring as an olive-brown, dark green, dark blue, or black powder; used intravenously as a diagnostic aid in the determination of blood volume, cardiac output, and hepatic function.
• Hoffman or iodine green : a triphenylmethane dye used as a chromatin stain.
• Janus green B / diazin green S : an azo dye used in supravital staining for the demonstration of mitochondria.
• malachite green / (new) solid green / light green N / Victoria green : a triphenylmethane dye used as a stain for bacteria and as an antiseptic for wounds.
• methyl green : a green basic triphenylmethane dye used as a histologic counterstain and as the DNA-staining component of methyl green–pyronin stain
• methylene green : a dye formed by nitrating methylene blue, interesting for its dark green metachromasia; it is a componenet of polychrome methylene blue
• Paris or Schweinfurt green / copper acetoarsenite : an emerald green powder derived by reaction of sodium arsenite, copper sulfate, and acetic acid; it is toxic by ingestion and is used as an insecticide and wood preservative
• silver or steel gray / nigrosin / indulin black : an aniline dye having a special affinity for ganglion cells, used to stain tissues from the central nervous system for study under the microscope
• blue :
• alcian blue : a copper-containing dye for staining acid mucopolysaccharides; it may be combined with periodic acid-Schiff reaction.
• alizarin or anthracene blue : a blue dyestuff derived from anthracene.
• alkali or isamine blue : a dye, sodium triphenylrosaniline monosulfate
• aniline, anthracene, China, marine, soluble (3M or 2R) or water blue : a mixture of the trisulfonates of triphenylrosaniline and of diphenylrosaniline
• aniline blue, W. S. : a mixture of the sulfonation products of mixtures of phenylated rosaniline and pararosaniline, soluble in water.
• Borrel's blue : a silver oxide stain for spirochetes.
• brilliant cresyl blue / brilliant blue C / C. brilliant blue / cresyl blue, 2R.N or B.B.S. : a basic dye of the oxazine group, usually C₁₅H₁₆N₃OCl, used chiefly for staining blood to demonstrate platelets and reticulocytes. The dye has a strong affinity for nucleic acid
• bromochlorphenol or bromchlorphenol blue : an indicator, dibromodichlorophenolsulfonphthalein, used in the determination of hydrogen ion concentration; yellow at pH 3.2 and blue at pH 4.8
• bromophenol or bromphenol blue : an indicator, tetrabromophenolsulfonphthalein, used in determining hydrogen ion concentration, being yellow at pH 3.0 and blue at pH 4.6
• bromothymol or bromthymol blue : a dye, dibromothymolsulfonphthalein, used as an indicator in determining hydrogen ion concentration, being yellow at pH 6.0 and blue at pH 7.6
• cyanol blue : a bright blue acid coal tar color related to triphenylmethane.
• Evans blue / T-1824 : a dye in the form of a green, blue green, or brown powder, C₃₄H₂₄N₆Na₄O₁₄S₄, injected intravenously to determine blood volume and movement
• Helvetia blue / methyl benzene / toluene
• indigo blue / indigotin : a neutral, tasteless, dark blue powder, the principal ingredient of commercial indigo
• soluble indigo blue / indigotindisulfonate sodium / indigo carmine / indicarmine : a  dye, occurring as a dusky, purplish blue powder or blue granules; used as a diagnostic aid for determining renal function, administered intravenously
• indophenol blue : the blue pigment produced in the Nadi reaction and in the indophenol test; it is (CH₃)₂N·C₆H₄·N:C₁₀H₆:O.
• Kühne's methylene blue : a mixture of methylene blue and dehydrated alcohol in phenol solution.
• Löffler's methylene blue : a mixture of methylene blue and alcohol in aqueous solution of potassium hydroxide.
• solvent blue 38 / Luxol fast blue MBS : an alcohol soluble dye used to stain myelinated nerve fibers
• Luxol fast blue stain : trademark for a group of dyes used in histology as stains for complex lipids, particularly myelin; they have a marked affinity for phospholipids, lecithin, and cephalin
• Swiss or methylene blue : methylthionine chloride; dark green crystals or crystalline powder having a bronze-like luster, readily reduced to colorless leukomethylene blue, which in turn is readily oxidized to methylene blue. Administered orally or intravenously in the treatment of congenital methemoglobinemia and intravenously in the treatment of toxic methemoglobinemia, and used as a bacteriological and pathological stain and as a diagnostic aid in the detection of the premature rupture of fetal membranes and to identify separate amniotic sacs in multiple pregnancies. An aniline dye much used as a staining agent; prepared in a saturated solution (7%) in absolute alcohol, which is diluted for use (e.g. Sabin-Feldman dye test for trophozoites of Toxoplasma gondii)
• methylene or toluidine blue O : a basic dye of the thiazine series (the chloride salt or zinc chloride double salt of aminodimethylaminotoluphenazthionium chloride) closely related to methylene blue. In routine preparations, toluidine blue stains basophilic nucleic and cytoplasmic ribonucleic acid ortho- or normochromatically (blue) and cartilage matrix and mast cell granules metachromatically (reddish purple). This is thus a metachromatic stain and is very useful for 1 µm sections of plastic-embedded tissue.
• polychrome methylene blue : a mixture of methylene green, methylene azure, methylene violet, and methylene blue.
• Nile blue, A. or sulfate : an oxazin dye which stains fatty acids blue; it is (C₂H₅)₂N·C₆H₃(ON)C₁₀H₅·NH₂·(SO₄) 1/2
• Lorrain Smith stain : Nile blue sulfate staining fatty acids blue and neutral fat pink.
• Berlin or Prussian blue : an amorphous blue powder, Fe₄[Fe(CN)₆]₃
• pyrrole blue : C₄H₄N·C[C₆H₄·N(CH₃)₂]₂.
• quinaldine blue : chemical name: 1-ethyl-2-[3-(1-ethyl-2(1H )quinolylidene)propenyl]quinolinium chloride. A bright blue-green stain, C₂₅H₂₅ClN₂, used in the cytodiagnosis of ruptured fetal membranes.
• spirit blue : a mixture of diphenylrosaniline and triphenylrosaniline
• thymol blue : an indicator, thymolsulfonphthalein, with an acid pH range of 1.2 to 2.8, being red at 1.2 and yellow at 2.8, and an alkaline pH range of 8.0 to 9.6, being yellow at 8.0 and blue at 9.6.
• benzamine 3 B / benzamine, benzo, chlorazol, diamine or trypan blue / azidine or Congo blue, 3 B. / naphthamine blue, 3 B. X. / Niagara blue, 3 B / dianil blue, H. 3 G. : an acid, azo dye that has been used in vital staining and as a remedy in protozoan infections; it is the sodium salt of toluidin-diazo-diamino-naphthol-disulfonic acid
• Victoria blue : a triphenylmethane dye with bacteriostatic properties.
• blue vitriol / copper sulfate / bluestone / cupric sulfate : the pentahydrate sulfate salt of copper, CuSO₄·5H₂O, a powerful emetic; used orally as an antidote to phosphorus poisoning. Topical application of a 1% solution is used in the treatment of phosphorus burns of the skin. It is also used as a catalyst with iron in the treatment of iron deficiency anemia. In 1:1,000,000 concentration it is used to prevent growth of algae in ponds, reservoirs, and swimming pools
• tetrazolium method : tetrazoliurn salts have low oxidation-reduction potentials and are thus capable of intercepting electrons in many biological oxidation-reduction reactions, including those facilitated enzymatically by dehydrogenases. The reduced, colored end product (blue diformazan) of these reactions is insoluble and thereby demonstrates the sites of such activity. Localization of the site of enzymatic activity is an important contribution to our understanding of cellular function. The methods of Nachlas, Walker, and Seligman are outstanding examples of this technique. Used for detection of acute myocardial infarction (not stained) at necropsy.
• formazan : reduced nitroblue tetrazolium (NBT : a yellow water-soluble dye) that is dark blue and water-insoluble; the reduction process is the basis of the nitroblue tetrazolium test
• azure : any of the partially methylated homologues of the series of basic dyes extending from thionine to methylene blue or to certain mixtures of members of this series. They are metachromatic and are used in many important staining procedures.
• azure I / azure B / methylene azure : trimethylthionine chloride; a dye used as a biological stain; it is a component of polychrome methylene blue
• azure II : a mixture of equal parts of azure I and methylene blue
• azure A : asymmetrical dimethylthionine, (CH₃)₂N·C₆H₃(SN)C₆H₃·NH₂·Cl.
• azure C : monomethylthionine chloride, (CH₃)N·C₆H₃(SN)C₆H₃NH₂·Cl.
• orange : a dye or stain that produces an orange color.
• acridine : a dibenzopyridine used in the synthesis of dyes and drugs; its derivatives are mostly fluorescent yellow dyes (acridine dyes), and those used in medicine (as antiseptic agents) are acriflavine hydrochloride, acriflavine base, and proflavine
• acridine or tetramethyl acridine : a fluorescent basic dye; sometimes used for vital staining
• ethyl orange : an indicator with a pH range of 2 to 4.
• orange G / wool orange / acid orange 10 : an acid azo dye used as a counterstain in histology and cytology and as a component of Mallory's acid fuchsin, orange G, and aniline blue stains.
• gold, methyl or Poirrier's orange / orange III / helianthin : an orange-yellow powder, the sodium salt of dimethylaminoazobenzene sulfonic acid, used as an indicator with a pH range of 3.2 to 4.4 and a color change from pink to yellow
• victoria orange : a salt of dinitrocresol used in histology as a stain.
• pseudoisocyanin : an orange metachromatic dye used for the selective demonstration of insulin in pancreatic islet b-cells.
• carmine / carminum / coccinellin : a red coloring matter whose active principle is carminic acid, which is extracted from cochineal (dried female insects, Coccus cacti) by the addition of alum and used as a histologic stain. This dye is of great historic interest, having been used in microscopic work in the eighteenth century, considerably before the days of modern histology. It is still of great use for staining embryos, small animals, and large blocks of tissue in toto and as a specific stain for glycogen and mucus. The active principle is carminic acid, which is extracted from cochineal (dried female insects, Coccus cacti)
• lithium carmine : vital stain for macrophages.
• Schneider's carmine : a saturated solution of carmine in concentrated acetic acid.
• orcinol / orcin : an antiseptic principle derived mainly from lichens, used as a reagent in various tests
• orcein : a brown coloring matter, derived from orcinol and soluble in alcohol; used as a specific stain for elastic tissue
• violet : a violet-colored dye.
• crystal, gentian, hexamethyl, methyl, Paris or pentamethyl violet / violet 7 B or C / violet G / dahlia B : a dye occurring as a dark green powder or greenish glistening pieces having a metallic luster, with antibacterial, antifungal, and anthelmintic properties, applied topically in the treatment of infections of the skin and mucous membranes associated with gram-positive bacteria and molds, and administered orally in pinworm and liver fluke infections. It has been given in strongyloidosis
• ammonium oxalate crystal violet : a type of Gram stain prepared by mixing 2 gm of crystal violet (90% dye content) and 20 mL of ethyl alcohol (95%) with 0.8 gm of ammonium oxalate and 80 mL of distilled water.
• cresyl violet acetate : a basic violet dye used as a stain for the central nervous system.
• cresyl or cresylecht violet : a dye used in pathologic staining.
• Hofmann's or iodine violet / dahlia : the term for certain unspecified mixtures of methylated and ethylated pararosanilines and rosanilines; C.I.42530. Sometimes used as a basic dye for violet staining
• Lauth's violet / thionine : a dark-green powder, giving a purple color in solution, and used as a metachromatic stain in microscopy
• methylene violet : one of the constituents of polychrome methylene blue
• neutral violet : a dye that resembles neutral red, but is more violet in color.
• amaranth : a red-brown dye, formerly made from amaranth plants but now made synthetically as an azo dye; formerly used as a coloring agent in food, cosmetics, and drugs
• bromcresol or bromocresol purple : an indicator, dibromo-o-cresolsulfonphthalein, used in the determination of hydrogen ion concentration, being yellow at 5.2 and purple at 6.8.
• brown :
• aniline, Bismarck, phenylene or Manchester brown : a basic aniline dye, phenylene-diazo-metaphenylene-diamine, C₆H₄[N₂C₆H₃(NH)₂]₂, much used as a stain and counterstain in histology
• Bismark brown R : a dark brown solid, synthetically prepared, used as a leather and textile dye and as a biological stain.
• Bismark brown Y : a blackish brown powder, synthetically prepared, used as a textile dye and as a stain for demonstrating mucus in intestinal goblet cells and cartilage in the trachea and in embryonic tissue.
• intravital, preagonal or vital staining : staining of a tissue by a vital dye (one that penetrates living cells and colors certain structures, without serious injury to the cells) which is introduced into a living organism and which, by virtue of affinity for certain tissues, will stain those tissues
• substantive staining : the coloration of tissues by direct absorption of dyes in which they are immersed
• brilliant cresyl blue
• lithium carmine
• methylene blue
• toluidine blue
• methyl violet stain : an aniline dye used as a bacteriological stain.
• Lugol's iodine stain = Me⁺I^-:K⁺I^-:H₂O in 1:1:100 molar ratio, containing 5% iodine; used as a stain for protozoa in wet mounts.
• dye exclusion test : the determination of cell viability in vitro. Following exposure of a cell preparation to trypan blue or eosin, dead cells take up the dye from the medium whereas living cells remain unstained.
• supravital staining : staining of living tissue removed from the body, but before cessation of the chemical life of the cells.
• Janus green B
• neutral red
• postvital staining : staining that occurs after death of a tissue which has been previously stained by vital methods
• non-vital stainings after fixation
• simple staining : staining with a single substance, such as the staining of microorganisms with a single dye
• direct stainings
• fluorescent staining : the coloration of tissues with a fluorescent dye
• quinacrine fluorescent method / Q method : chromosomes are exposed to quinacrine derivatives, after which they fluoresce, the degree of fluorescence varying from one chromosome segment to another; the resultant fluorescent patterns (Q bands) are characteristic for each chromosome
• bacterial stainings :
• polar staining : staining in which the ends of the rod stain deeply while the central portion of the organism is nearly or quite unstained, as in the pasteurellas
• bipolar staining : staining at the 2 poles only, or staining differently at the two poles.
• Dieterle's stain : a silver impregnation method for staining Legionella and other organisms. Slides are sensitized in uranyl nitrate, treated with gum mastic, incubated in silver nitrate, and developed in a solution of hydroquinone, sodium sulfite, acetone, formaldehyde, pyridine, and gum mastic. Cells stain black on a yellow-tan background.
• Löffler's alkaline methylene blue stain : a simple stain used especially for demonstrating granules in Corynebacterium diphtheriae. Methylene blue made alkaline with potassium hydroxide is applied to a smear briefly and the slide washed. Granules appear deep blue in lighter blue cells.
• silver impregnations
• Achúcarro's stain : a silver-tannin stain for impregnating connective tissue
• neuronal stainings
• acid fuchsin stain : a diffuse stain containing acid fuchsin and diluted hydrochloric acid in purified water, for demonstrating axons and as a component of connective tissue stains
• Bethe's method : a method of fixing methylene blue stains of nerve fibers
• Bielschowsky's method : a method for demonstrating axons and neurofibrils using an ammoniacal silver stain. This method consists of silver salt impregnation of blocks of tissue and the subsequent reduction of the silver. As a result, there is silver impregnation of neurofibrils, axons, and dendrites. Other structures, such as connective tissue fibers and neuroglia, may be impregnated. This method is valuable for the study of motor and sensory nerve endings. Nerve fibers appear black
• Perdrau's method : modification of Bielschowsky's method for staining collagen and reticulin.
• Bodian's silver method : a method of staining nerve fibers and nerve endings with colloidal silver in paraffin sections. It was developed by Bodian in 1937. Sections are saturated with an aqueous solution of protargol in the presence of metallic copper. The colloidal silver proteinate is then reduced in hydroquinone, and the silver is replaced by gold chloride (toning with gold). Excess silver is removed by sodium thiosulfate. This method gives uniform, sharp, and specific staining of neural elements, including axons, neurofibrils, and synaptic end feet. Axons appear black or deep blue
• Bowie stain : a stain used to demonstrate the slightly basophilic cytoplasm and the specific granules of juxtaglomerular cells.

Cajal's gold sublimate method (1913): a method of staining astrocytes by a gold chloride–mercuric bichloride compound. This method is considered to be the first highly selective neuroglial stain to be developed. It is usually used on frozen sections of material fixed in formalin-ammonium bromide mixture. The chemicals and water used must be of exceptional purity for best results. Protoplasmic and fibrous astrocytes appear reddish purple to near black
• Cajal's double method : a method of demonstrating ganglion cells.
• Davenport's stain : stain for demonstrating various elements of nerve tissue, dependent upon the special affinity of nerve cells and their processes for silver.
• Golgi-Cox method / Cox's modification of Golgi's corrosive sublimate method : a method for staining ganglion cells. Golgi silver methods for nerve cells depend upon preliminary fixation in a potassium dichromate solution. The silver is selective, tending to impregnate a few nerve cells completely, which then become blackened when the silver is reduced. Although these methods do not reveal details of the internal structure of nerve cells, they do provide, very importantly, a unique view of the entire cell and its processes. They also demonstrate specific details of non-nervous cells and tissue components such as the parietal cells of the stomach and bile canaliculi of the liver. The Golgi-Cox method is one of the simplest of the complex and time-consuming Golgi methods for demonstrating the relations of dendrites and axons to the nerve cell body. Cell bodies and processes are stained black on a light yellowish or colorless background. Blood vessels may also be impregnated.
• Golgi's mixed method : method of staining nerve cells and all of their processes; historically of very great importance.
• Grimelius' argyrophil method : a method for demonstrating granule-containing cells such as APUD cells. Incubation in a buffered silver nitrate solution is followed by reduction in a hydroquinone and sodium sulfite solution; reactive cell granules appear black.
• Harris' method : a method for demonstrating Negri bodies
• Marchi's method and modifications (Swank and Davenport) : a method of demonstrating degenerated nerve fibers, the tissue first being fixed in a solution containing potassium bichromate, which prevents the normal myelinated fibers from staining with osmic acid. Normal adult myelin contains no hydrophobic neutral lipids (triglycerides and cholesterol esters), whereas degenerating myelin does. All ethylenic (double) bonds, such as those found in fatty acids of all lipids, will reduce osmium tetroxide to the lower oxides and black metallic osmium. They cannot do this, however, if previously or simultaneously oxidized. Thus, if degenerating (hydrophobic) and normal (hydrophilic) myelin lipids are exposed to aqueous potassium chlorate, only normal myelin ethylene bonds will be attacked. Unaffected bonds of degenerating myelin are thus the only ones still free to reduce osmium tetroxide. Nervous tissue in which degenerating myelin is present is fixed for 2 to 3 days in either formalin or a magnesium sulfate-potassium clichromate mixture followed by formalin. The tissue is then placed for 8 to 10 days in a solution containing potassium chlorate, osmium tetroxide, formaldehyde, and glacial acetic acid. After a thorough wash, the tissue is embedded in celloidin (nitrocellulose), sectioned, and mounted. Degenerating myelin and neutral lipids elsewhere will be black. Normal myelin is unstained.
• Nissl's method : a method employed in the study of nerve cell bodies.
• Pal-Weigert method (1887) : a modification of the Weigert's myelin sheath stain in which the differentiation between the myelinated fibers and the surrounding tissues may be carried to a greater degree than in the original method, the specimen being treated for several weeks in a solution containing potassium bichromate. Originally Müller's fluid was used as the fixative; later, formalin was used. Several modifications of the original Pal-Weigert method are available. Normal myelin sheaths are stained deep blue. Degenerative myelin does not stain
• Ranson's pyridine silver method or stain (1911) : stain used for demonstrating unmyelinated nerve fibers and their processes. The largest myelinated axis cylinders are usually yellow, surrounded by a colorless ring of myelin, and there is a gradation to black in the small myelinated fibers. Unmyelinated fibers are typically dark brown or black. Nerve cells are yellow to brown, with dark brown to black neurofibrils. End bulbs, when stained, appear black or as small black rings.
• argentaffin stainings
• Fontana-Masson stain : an ammoniacal silver nitrate stain for melanin and argentaffin material; used in the diagnosis of melanoma, pheochromocytoma, and carcinoid tumors.
• methenamine silver stain : a methenamine silver solution used together with gold chloride, sodium thiosulfate, and a safranin O counterstain; argentaffin granules are black while granules of mast cells remain red. Used also to detect Pneumocystis carinii
• blood stainings
• Jenner's method : a method for demonstrating blood corpuscles
• polychrome methylene blue : a stain for demonstrating plasma cells and mast cells, employing potassium carbonate and methylene blue.
• relief staining : a method of staining that colors the background and leaves the cells uncolored.
• indirect or negative staining : staining of the background and not the organism, to facilitate the microscopical study of bacterial capsule.
• India ink capsule stain : a method of demonstrating cell capsules, especially of Cryptococcus neoformans. The smear is mixed with India ink, covered with a coverglass, and examined microscopically. Capsules appear as a clear halo around the cells against a black background.
• Anthony capsule stain : a method of demonstrating the capsules of bacteria. A smear of a milk culture is air dried, or a smear is mixed with milk and dried. The slide is stained with crystal violet and washed with copper sulfate. The capsule appears unstained against a purple background; the cells are deeply stained.
• acidic dyes (nigrosin, ...) : electrostatic repulsion from negatively-charged polysaccharides
• ruthenium red
• methylene blue
• toluidine blue
• phenicated thionine
• Neufeld capsular filling reaction or quellung test : Abs against capsular polysaccharides allow permeabilization and the swallen capsule becomes viewable under electron microscopy.
• Hiss capsule stain : a method of demonstrating bacterial capsules. Smears are treated with crystal violet, heated, and rinsed with copper sulfate solution. Capsules appear as pale blue halos around deep blue to purple cells
• AgNO₃ impregnations
• Fontana-Tribondeau stain : a method of staining spirochetes by silver impregnation, using ammoniacal silver nitrate solution (tannine + AgNO₃ in NH₃)
• Levaditi's method : a method for demonstrating Treponema pallidum in sections, employing reduced silver
• Steiner method
• multiple staining : staining with several different dyes to facilitate identification of different tissue elements.
• differential staining : staining with a substance for which different bacteria or different elements of the bacteria or specimen being stained show varying affinities, resulting in their differentiation.
• differential stain : one that facilitates differentiation of various elements in a specimen.
• contrast stain : material used to color an unstained portion of a tissue after another portion has been stained with another dye.
• double staining : staining with two different dyes which have an affinity for different tissue elements.

Stains :
• bacterial stainings
• alcohol- and acid-fast stain : a staining procedure for demonstrating acid-fast microorganisms
• carbolfuchsin stain : a stain for microorganisms containing basic fuchsin with dilute phenol as a mordant. It is also used as a counterstain for Legionella pneumophila following other routine stains. Stained cells appear pink to red.
• Gimenez stain : a method for staining Chlamydia spp., Rickettsia spp. and Legionella spp.. Smears are stained with carbol–basic fuchsin solution, washed, and counterstained with malachite green. Cells appear red against a greenish background.
• Kinyoun carbolfuchsin stain : a stain for acid-fast organisms. A heat-fixed smear is treated with carbolfuchsin solution. The slide is washed with water, decolorized with acid alcohol, and counterstained with methylene blue. Acid-fast organisms appear red against a blue background.
• May's spore stain : a method of staining the spores of bacteria in which they are treated with 5% chromic acid, then with ammonia, stained with hot carbol-fuchsin, decolorized with dilute sulfuric acid, and counterstained with methylene blue. The spores appear red, the vegetative cells blue.
• Fite's method : a staining method used for acid-fast bacilli. Tissue sections are deparaffinized in 2:1 xylene and peanut oil, then stained with Ziehl-Nielsen carbolfuchsin, decolorized with acid alcohol, and counterstained with methylene blue.
• Ziehl-Neelsen staining : a heat-fixed smear is flooded with carbolfuchsin (phenicated fuchsin) 1%, a red dye that penetrates waxy cell walls under heat, heated for 5', cooled, and washed. The slide is decolorized with acid alcohol (ethanol 97% + HCl or H₂SO₄ 3%), which removes carbolfuchsin from other Bacteria but not from alcohol- and acid-fast organisms. Finally, the smear is washed and counterstained with methylene blue or malachite green for 30".Acid-fast organisms appear red against a blue background.
• Ziehl-Neelsen carbolfuchsin : a mixture of basic fuchsin, alcohol, liquefied phenol, and purified water.
• Truant auramine-rhodamine stain : a method for demonstrating mycobacteria. A smear is heat fixed, stained with auramine-rhodamine solution, decolorized, counterstained with potassium permanganate, and examined under ultraviolet light; acid-fast organisms glow with a yellow-orange color.
• Albert's diphtheria stain : a stain containing toluidine blue and methyl (or malachite) green. Following treatment with iodine solution, the metachromatic granules appear black, the bars dark green to black, and the remainder of the diphtheria bacillus a light green.
• Castañeda staining : a method of demonstrating Rickettsia spp.. A smear is air dried and treated with methylene blue, then counterstained with safranin O, washed, and air dried. Rickettsiae appear blue against red cellular elements
• Gram's method or stain (1888) : an empirical staining procedure devised by Gram in which microorganisms are stained with fuchsin examethylate (a.k.a. gentian violet or crystal violet) 1% (1'), treated with 1:15 dilution of Lugol reactive (it acts as a mordant causing crystal violet molecules to join each other) (20"), decolorized with ethanol or ethanol-acetone 7:3 ^v/v or ethanol 95 % (Eukarya and Gram -ve Bacteria lose the violet color when they are treated) (1-2'), and counterstained with a contrasting dye, usually safranin O (light pink or red). Those microorganisms that retain the crystal violet stain are said to be gram-positive, and those that lose the crystal violet stain by decolorization but stain with the counterstain are said to be gram-negative (Eukarya and Gram -ve Bacteria). Please note Gram staining depends on pH and culture age (old Gram +ve cells may appear Gram -ve because they loose cell wall !)
• Leifson flagella stain : a method for demonstrating bacterial flagella. Smears are air dried, treated with alcoholic pararosaniline–tannic acid solution, and washed. Flagella are visible against a clear background
• Macchiavello's stain : a stain used especially for Chlamydia, Coxiella burnetii and Rickettsia spp.. The heat-fixed smear is stained with basic fuchsin, decolorized in citric acid, and counterstained with methylene blue. Rickettsiae stain red against a blue background
• McFadyean reaction : staining of Bacillus anthracispoly-D-Glu capsule with polychrome methylene blue
• Warthin-Starry silver stain : a method for staining Bartonella spp. and spirochetes. A smear is air-dried, immersed in absolute ethanol, washed in distilled water, and incubated in 2% silver nitrate. The cover glass is then developed in a mixture of silver nitrate, gelatin, glycerol, agar, and hydroquinone. Organisms appear black on a light background.
• Wayson stain : a method used to demonstrate polar staining. A smear is treated with a mixture of basic fuchsin and methylene blue with phenol, washed with water, and dried. It is used especially to demonstrate Yersinia pestis in specimens from tissues and lymph nodes
• Wirtz-Conklin spore stain : a smear is heated with malachite green (endospore stain) (10-20'), rinsed, then counterstained with safranin O 0,25% (light pink or red color counterstain for Bacteria) (1'). Spores appear green in red-stained cells.
• fungal stainings
• Grocott-Gomori methenamine–silver nitrate stain (GMS) : a method for demonstrating actinomycetes and fungi in tissue. Sections are treated with chromic acid (HCrO₄) for 1 hr., NaH₂SO₃ 1%, stained with methenamine-silver nitrite solution at 60°C (1 hr.) + AuCl₂ 0.1% (some ') + NaH₂SO₃ 2% + , and counterstained with light Janus green solution 0.2% (30-50") => alcohol dehydratation. Cells appear brown against a green background.
• Cotton blue staining (for Fungi) :
• alum-carmine stain : a preparation of ordinary alum and carmine
• Alzheimer stain : a methylene blue and eosin polychrome stain for demonstrating Negri bodies
• Bensley's neutral gentian orange G stain : a preparation used for demonstrating secretion granules.
• carbol–gentian violet stain : a solution containing gentian violet and carbolic acid.
• chromosome stainings
• F or F-staining method : chromosomes are treated with phosphate buffer, rinsed and stored for 60–72 hours in saline citrate solution, then fixed in methanol-acetic acid, and stained by the Feulgen method.
• Feulgen staining : H⁺Cl^- + pink anylin. It stains nucleic acids in red.
• telomeric or terminal staining : differential staining of chromosomes to stain chromosome telomeric regions, consisting of pretreatment with a heated salt solution before treatment with buffered Giemsa stain or acridine orange; only the telomeric regions of the chromosomes retain the stain.
• Gomori's aldehyde fuchsin stain : this is a valuable stain that is compatible with a number of rather striking staining procedures. Aldehyde fuchsin has a poorly understood affinity for elastic tissue, beta granules in pancreatic islets, neurosecretory material, mast cell granules, and b-cells in the pituitary. The principal ingredients are basic fuchsin and paraldehyde. Several counterstains may be used. A counterstain is one that enhances the appearance of another primary stain but, in actual practice, usually provides additional specific information. Hyaline cartilage, elastic fibers, mucin, mast cell granules, and b-cells stain purple. Other tissues are stained according to the counterstain used
• modified aldehyde fuchsin stain : Halmi's modification of Gomori's method utilizes aldehyde fuchsin with light green or orange G as the counterstain. Nuclei can be stained with celestine blue or haemalum (alum hematoxylin). Depending upon the concentration of organelles found in different cell types, they may appear yellow, purple, or green. Collagen and the basement membrane are green, and mast cells, elastic fibers, and goblet cell mucus are purple.
• Gomori's chrome alum hematoxylin stain : primary fixation should be with Bouin's or Helly's fluids, although secondary treatment by these fluids of formalin-fixed material is satisfactory. This method uses chrome haemalum (alum hematoxylin) stain with phloxine B as a counterstain. Basophils stain blue and acidophils appear red. In the posterior pituitary gland, neurosecretory substances stain deep blue.
• hematoxylin-eosin (H&E) stain : a mixture of hematoxylin in distilled water and aqueous eosin solution, employed also universally for routine examination of tissues; numerous variations are employed in execution of the stain. This is the most widely used and important general purpose stain combination. It may be used after any fixation except osmium tetroxide. Nuclear stain is the basic hematoxylin, whereas the cytoplasmic counterstain is eosin. Nuclear heterochromatin stains blue and the cytoplasm of cells rich in ribonucleoprotein also stains blue. The cytoplasm of cells with minimal amounts of ribonucleoprotein tends to be lavender in color, whereas the mature red blood cell and muscle contractile protein, which are devoid of RNA, stain red. Although it is an esthetically pleasing combination and is widely used, it is limited in its ability to differentiate cytoplasmic organelles and many other tissue components.
• iron hematoxylin method : a staining procedure in which the sections are treated with an iron salt, stained with hematoxylin, and differentiated with the same iron salt.
• Heidenhain's iron hematoxylin stain : an important cytological method for the demonstration of most cellular structures: nuclei, chromosomes, centrioles, fibrils, mitochondria, cilia, etc. This is one of the standard stains capable of excellent results after any good fixation. Tissues are stained in aqueous hematoxylin after mordanting in iron ammonium sulfate (iron alum). Many counterstains can be used. It is not specific for any structure but is particularly useful for demonstrating cell membranes, terminal bars (tight junctions or junctional complexes), secretory granules, nuclear heterochromatin, mitochondria (if preserved), and the cross striations of voluntary muscle. All these structures stain black
• Regaud's method (1910) : a modification of Heidenhain's iron hematoxylin method for mitochondria, which consists of prolonged mordanting of tissues in potassium dichromate. It stains mitochondria blue-black. It is the most permanent and the simplest of all mitochondrial stains
• Weigert's iron hematoxylin stain : a simple method for staining most nuclear and cytoplasmic constituents.
• blood stainings
• Kleihauer and Betke acid eluition test : in phosphate citrate buffer at pH 3.3, HbF, but not HbA, resist eluition and so HbF-containing RBCs can then be stained by erythrosine.
• May-Grünwald stain : an alcoholic neutral mixture of methylene blue and eosin.
• Michaelis' stain : a mixture of alcoholic solution of methylene blue and a solution of eosin in acetone; used for demonstrating blood corpuscles.
• Romanovsky's (Romanowsky's) stain : the prototype of the many eosin-methylene blue stains for blood smears and malarial parasites, including
• Giemsa stain : a solution containing azure II-eosin, azure II, glycerin, and methanol. The stain is composed of methylene blue eosinate, azure A eosinate, azure B eosinate, and methylene blue chloride; used for differential staining of blood smears, spleen, and bone marrow cells, for staining protozoan parasites such as Plasmodium spp. and Trypanosoma spp., for Chlamydia spp. as well as for the identification of viral inclusion bodies. The stained nuclei and chromosomes may vary in color from reddish-blue to purple to pink.
• reverse (R) Giemsa method : a method in which the reciprocal (R-bands) of the banding pattern seen in the Giemsa method for chromosomes is obtained
• T-staining method : a method for staining only the terminal ends of chromosomes by means of either Giemsa stain or acridine orange; it results in bands (T bands) of dark violet (Giemsa) or fiery orange (acridine orange)
• Leishman's stain : a mixture of methylene blue and eosin for staining blood cells and certain parasites.
• Wright's stain : a differential stain for blood corpuscles and malarial parasites named after the American pathologist James Wright (11869-1928), who described this method in 1902. The main constituents of his stain are methylene blue and eosin. Erythrocytes bind eosin and appear red or pink; nuclei, deep blue or purple; basophilic granules, deep purple; eosinophilic granules, red to red-orange; neutrophilic granules, reddish-brown to lilac; platelets, violet to purple; and lymphocyte cytoplasm, pale blue.
• urine stainings
• Sternheimer-Malbin staining : crystal violet + safranin O. Used to stain young leukocytes in urine of patients affected by acute pyelitis.
• Seyderhelm's solution : a colloidal mixture of Congo red and trypan blue, for staining urinary sediment.
• Sternheimer-Malbin stain : a stain used in urinalysis which has ready affinity for hyaline casts, epithelial casts, red cells, bladder epithelial nuclei, nuclei of vaginal epithelium, and trichomonads, staining each a different color.
• Papanicolaou's stain : a method of staining smears of various body secretions, from the respiratory, digestive or genitourinary tract, for the examination of exfoliated cells, to detect the presence of a malignant process. hematoxylin + ?
• periodic acid-Schiff reactive (PAS) method or reaction : H₃IO₄ 0.5% => leukofuchsin (Schiff's reagent) 0.5% (in 20 mL of H⁺Cl^- 1N and Na₂HSO₃ and NaH₂SO₃ 0.5%) (115') => washing under water (10') => counterstaining with eosin and light green (1') of Janus green (=> alcohol dehydratation => xylol clearing). This method is principally used to demonstrate structures rich in polysaccharides (glycogen), mucopolysaccharides (e.g., ground substance of connective tissues, basement membrane, and mucus), glycoproteins (thyroglobulin), and glycolipids. This method depends upon the selective oxidation by periodic acid of 1,2-glycols and 2,2-amino alcohols to aldehydes. The aldehydes are then detected by the Schiff reagent, which stains them reddish purple
• Seller's stain : a combination of alcoholic solutions of methylene blue and basic fuchsin which stains Negri bodies a bright red against a purplish-pink background; used in rapid diagnosis of rabies.
• Sudan black B fat stain : a stain used to demonstrate Legionella spp. and fat vacuoles in bacterial cells. A heat-fixed smear is treated with Sudan black B, cleared with xylol, and counterstained with safranin O. Fat vacuoles stain blue-black; bacterial cells stain pink.
• Tzanck smear or test : examination of tissue from the floor of a lesion, in vesicular or bullous diseases, to discover the type of cell present as a means of diagnosing the disease. Introduced by Arnault Tzanck [Russian dermatologist in Paris, 1886–1954], it has been used for many years in the diagnosis of bullous and vesicular dermatoses : multinucleated giant cells are pathognomonic of varicella, herpes simplex, herpes zoster (if obtained in the vesicular stage), or pemphigus. A quick staining can be done by Hemacolor or Diff-Quik within 1'. The sensitivity of the Tzanck smear exceeds 80%, and the specificity 90% when the investigators are experienced. A disadvantage is that the smear cannot differentiate between herpes simplex virus or varicella-zoster virus infections. Cytology will, however, never replace culturing or histopathology.
• van Gieson's solution of trinitrophenol and acid fuchsin : a stain for connective tissue, consisting of acid fuchsin 0.05% and saturated aqueous solution of trinitrophenol / picric acid. Collagen is stained in red.
• triple staining : staining with 3 different dyes to facilitate identification of the different elements.
• Ehrlich's triacid stain : a stain containing acid fuchsin, orange G, and methyl green; used for demonstrating various formed elements in the blood.
• hematoxylin-eosin-azure II : Maximow's method for the staining of blood-forming organs.
• Gomori trichrome stain is a staining procedure that combines the plasma stain (chromotrope 2R) and connective fiber stain (fast green FCF) in a phosphotungstic acid solution to which glacial acetic acid has been added.
• Halmi's aldehyde-fuchsin trichrome (AFT) stain : proposed originally by Halmi (1952) for use in differentiating subpopulations of basophils in the hypophysis, this method utilizes the sequential staining of Bouin's or susa-fixed tissue (Romeis, 1948) by (a) immersion in aldehyde fuchsin, (b) nuclear staining with Ehrlich's hematoxylin, and (c) a rapid, single-step counterstain using light green, orange G, and Chromotrope 2R (optional) dissolved in a phosphotungstic-acetic acid mixture. The stain has subsequently found application as a general-purpose "tri-chrome" stain in a variety of tissues. Collagenous fibers stain green; nuclei, blue; nucleoli, red; erythrocytes, orange; colloid, pink; and cytoplasm, grey
• Mallory's connective tissue stain : this is one of the most beautiful and widely used of all stains. Several modifications of the original method have been developed. Basic ingredients are acid fuchsin, aniline blue, orange G, and phosphotungstic acid. Collagen and reticular fibers stain blue; elastic fibers, yellow or pink; nuclei, fibrin, and neuroglial fibrils, red
• Mallory's triple stain / Mallory's acid fuchsin, orange G, and aniline blue stain : a stain for demonstrating connective tissue and secretion granules
• Heidenhain's azan stain / Mallory-azan stain : Heidenhain's modification of Mallory's original connective tissue triple stain, in which azocarmine is used instead of acid fuchsin along with the aniline blue-orange G mixture. Collagen and basophil granules stain 502 blue; muscle and acidophil granules, orange to red; and nuclei and cytoplasm, red. Elastic fibers are unstained or, if stained, yellow or pink. Mallory-azan is an extremely useful and beautiful stain combination. Heidenhain was the first histologist to use the azan modification of Mallory's stain
• Mallory's phloxine B–methylene blue stain : a stain used in histology to demonstrate connective tissue.
• Mallory's phosphotungstic acid–hematoxylin (PTAH) stain : a stain used for demonstrating nuclear and cytoplasmic detail and connective tissue fibers. It is an ideal stain for the demonstration of astroglial fibers, which stain blue as do striated muscle fibers and mitochondria. Collagen, reticular fibers, and ground substance of bone and cartilage stain in varying shades of yellow to brownish red. Coarse elastic fibers stain purple. Nuclei are blue.
• Masson's trichrome method or stain : this method was first described by Pierre Masson in 1951. Although Bouin's is the recommended fixative, Orth's (formalin-Müller), Zenker's, or formalin in alcohol may be used. Dyes and solutions used are hematoxylin, acid fuchsin, phosphotungstic acid, and light green. Several modifications of this method are available. Nuclei stain dark blue / purple; cytoplasm and neuroglial fibers, red; collagen in connective tissue, green / light blue.
• May-Grünwald and Giemsa (MGG) staining : methylene blue + eosin in a undiluited methanol fixative solution + a same quantity of H₂O (3') + Giemsa 1:10 (15'-20').
• Mayer's hemalum : an aqueous solution of hematein, alum, thymol, and 90% alcohol.
• Milligan's trichrome stain : a differential stain for connective tissue and smooth muscle. Nuclei and muscle appear magenta; collagen appears green or blue, depending on whether fast green FCF or aniline blue is used as a counterstain; and red blood cells appear orange to orange red.
• Gomori-Wheatley trichrome stain : a rapid staining method which adequately demonstrates structural details of the various intestinal protozoa. The solution is as follows: chromotrope 2R 0.6 g, light green SF 0.3 g, phosphotungstic acid 0.7 g, acetic acid 1.00 mL, and distilled water 100.00 mL
• tetrachrome stain : a stain combining eosin, methylene blue, azure A, and methylene violet, in methyl alcohol.
• amphocyte, amphophil, amphophilic, amphochromatophil, or amphochromophil cell : one that stains readily with either acid or basic dyes
• metallophil cells : cells in which the cytoplasm has a great affinity for metal salts; these are cells of the reticuloendothelial system (RES), and also a series of related cells that are not selectively stained by vital staining.
• electron stains : substances containing heavy atoms (heavy-metal stain : any of the elements of high atomic weight often used as stains in electron microscopy), such as osmic tetroxide, uranyl, and lead ions, which, under certain conditions, act as “electron stains,” comparable to histologic stains, by combining selectively with certain regions of the specimen; used in the visualization of the ultrastructure.
• estrogen receptor probing compound (ERPC) is composed of estradiol-BSA-biotin and can be used to detect functional estrogen receptor expression in both Western blot and immunohistochemistry. ERPC based techniques are non-radioactive, sensitive, relatively inexpensive, and can be used with all species. The use of both ERPC and ERa- or ERb-specific antibodies provides complementary information in characterizing estrogen receptors' expression and functional binding to ligand^ref
Aims of histochemistry  :
• detection of pathogenetic process
• hemacytometer / counting cell or chamber / hemocytometer : a device used in manual blood counts, consisting of a microscopic slide with a depression whose base is marked in grids, and into which a measured volume of a sample of blood or bacterial culture is placed and covered with a cover glass. The number of cells and formed blood elements in the squares is counted under a microscope and used as a representative sample for calculating the unit volume
• Abbe-Zeiss or Thoma-Zeiss counting chamber
• Zappert's chamber
Solutions used in diluting blood prior to counting :
• Callison's fluid : distilled water, Löffler's methylene blue, formaldehyde solution, glycerin, ammonium oxalate, and sodium chloride
• Hayem's solution : mercury bichloride, sodium chloride, and sodium sulfate
• Gowers' solution : sodium sulfate, glacial acetic acid, and water
• Toison's fluid or solution : gentian violet, sodium chloride, sodium sulfate, glycerin, and water
• Fonio's solution : a solution of magnesium sulfate in water, used as a diluent for blood platelets.

Piazza's fluid : a blood-coagulating fluid composed of sodium chloride and ferric chloride in water

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