Acid alcoholic brilliant cresyl blue stain for gastric and other mucins

Summary Some but not all samples of brilliant cresyl blue (6-methyl-7-dimethylamino-2-phenoxazin chloride) under C. I. No. 51010 in Conn's Biological Stains when dissolved at 1% level in 50–70% alcohol containing 1% concentrated (12 N) hydrochloric acid, stain (in 30 min) a wide variety of human and laboratory animal mucins blue black on an almost unstained background. The mucoprotein of the gastric surface epithelium and of the peptic gland neck cells of several species reacts strongly. A 16 hr 60° C methylation in 0.1 M methyl-sulfuric acid in methanol is required to block the staining of these gastric and some intestinal mucins, while 1–2 hr intervals suffice to prevent the staining of mast cells, cartilage and metachromatic sulfomucins generally. Saponification (1% KOH/70% alcohol, 20min) does not restore staining in either location group, indicating that sulfate mucins are probably reacting in both.Most other basic dyes fail to stain mucins from acid alcohol solutions: azure A, toluidine blue, resorcin blue, orcein, resorufin, azoresorufin brown, azolitmin, lacmoid, gallocyanin, Nile blue, methylene green, pararosanilin, crystal violet, Victoria blue R. Some staining occurred with one of three lots of Victoria blue B, with two lots of Victoria blue 4 R and with one lot each of Bernthsen's methylene violet, elastin violet PR and elastin purple PP.The stain may be preceded by the Feulgen reaction to give red nuclei, or followed by a brief collagen stain in an alcoholic acid fuchsin (0.05–0.1%), picric acid (1.5%) solution.Presented before the Symposium of the Histochemische Gesellschaft in Hamburg, 28. September 1968.Supported by National Cancer Institute Grant No. C-4816, National Institutes of Health.     

Studies in Gram Staining

Gram-negative bacteria stained with crystal violet are decolorized by 95% alcohol within 2 min, whereas Gram-positive bacteria require at least 3 min treatment. Aqueous solutions of safranin, neutral red, and fuchsin replace crystal violet from stained Gram-positive bacteria more quickly than alcohol alone, and alcoholic solutions of these counterstains are in most cases still more effective. Treatment of crystal viokt-stained organisms with alcoholic safranin (0.25%) for 15 scc will distinguish Gram-positive bacteria (viokt) from Gram-negative bacteria (pink).

Alcohol containing very low concentrations of iodine generally decolorizes crystal violet-stained Gram-positive bacteria more quickly than alcohol alone. Increasing concentrations of iodine in alcohol reduce the rate of decolorization of stained bacteria, but stained Gram-negative bacteria are still readily dccolorized. The addition of 0.1% iodine to alcohol increases the rate of extraction of crystal violet by alcohol from Gram-negative organisms, but delays extraction of dye from Gram-positive organisms, and this applies when counterstain is also present. A two-solution modification of Gram staining is described in which crystal violet-stained bacteria are treated with an alcoholic solution of safranin, fuchsin, and iodine.     

Cytological Methods for Crepis Species

Root tips of Crepis species are fixed in La Cour's “2BE” and dehydrated thru a butyl alcohol series. They are stained in 1% crystal violet for 1 hour, with chromic acid and iodine as pre-and post-staining mordants, respectively, and passed thru dehydrating alcohols containing picric acid and ammonium hydroxide. Differentiation is done in clove oil. The method is rapid; the chromosomes are dark purple; the centromere is not stained; and the cytoplasm is clear. By further controlled destaining the hetero-chromatic segments within the chromosomes may be located.

Pollen mother cells are fixed in acetic alcohol (1:4) and squashed in aceto-carmine. A method is described for making semi-permanent preparations mounted in diaphane.

Pollen grains are mounted in lacto-phenol with acid fuchsin or anilin blue W. S. as the dye.     

Cytological Methods for Crepis Species

Root tips of Crepis species are fixed in La Cour's “2BE” and dehydrated thru a butyl alcohol series. They are stained in 1% crystal violet for 1 hour, with chromic acid and iodine as pre-and post-staining mordants, respectively, and passed thru dehydrating alcohols containing picric acid and ammonium hydroxide. Differentiation is done in clove oil. The method is rapid; the chromosomes are dark purple; the centromere is not stained; and the cytoplasm is clear. By further controlled destaining the hetero-chromatic segments within the chromosomes may be located.

Pollen mother cells are fixed in acetic alcohol (1:4) and squashed in aceto-carmine. A method is described for making semi-permanent preparations mounted in diaphane.

Pollen grains are mounted in lacto-phenol with acid fuchsin or anilin blue W. S. as the dye.     

Studies in gram staining.

Gram-negative bacteria stained with crystal violet are decolorized by 95% alcohol within 2 min, whereas Gram-positive bacteria require at least 3 min treatment. Aqueous solutions of safranin, neutral red, and fuschsin replace crystal violet from stained Gram-positive bacteria more quickly than alcohol alone, and alcoholic solutions of these counterstains are in most cases still more effective. Treatment of crystal violet-stained organisms with alcoholic safranin (0.25%) for 15 sec will distinguish Gram-positive bacteria (violet) from Gram-negative bacteria (pink). Alcohol containing very low concentrations of iodine generally decolorizes crystal violet-stained Gram-positive bacteria more quickly than alcohol alone. Increasing concentrations of iodine in alcohol reduce the rate of decolorization of stained bacteria, but stained Gram-negative bacteria are still readily decolorized. The addition of 0.1% iodine to alcohol increases the rate of extraction of crystal violet by alcohol from Gram-negative organisms, but delays extraction of dye from Gram-positive organisms, and this applies when counterstain is also present. A two-solution modification of Gram staining is described in which crystal violet-stained bacteria are treated with an alcoholic solution of safranin, fuchsin, and iodine.     

The Mechanism of the Gram Reaction. III. Solubilities of Dye-Iodine Precipitates and Further Studies of Primary Dye Substitutes

Solubilities of dye-iodine precipitates in alcohol and in aqueous safranin solution were determined by direct solubility methods and by photocolorimetric methods. It was found that, increasing precipitate solubility in alcohol or safranin solution gave decreasing differentiation between Gram-positive and Gram-negative bacteria. Dyes which did not stain the cells well as a primary stain did not give good Gram stains, regardless of the solubilities of their precipitates. Some dyes (typified by methylene blue) which gave relatively alcohol-insoluble iodine precipitates gave inferior Gram differentiation because these precipitates were readily soluble in the safranin counterstain.

Solubilities of precipitates of crystal violet and various iodine substitutes were determined photocolorimetrically. The ability of a substance to replace iodine in the Gram stain correlated with its ability to give a precipitate which was only slightly soluble in alcohol and relatively insoluble in aqueous safranin solution.

It was concluded that the usual Gram reagents are not truly specific for the differentiation. Any dye and mordant could be used if the dye was deeply colored, stained the cells well, and if the precipitate of dye and mordant was only slightly soluble in alcohol and relatively insoluble in the counterstain. These factors, combined with those influencing differences in cell membrane permeability, constitute the most important factors in the Gram stain differentiation.

Studies were made concerning the ability of dyes to substitute for crystal violet in the Gram procedure. Of 29 dye samples reported on here for the first time none proved to be good substitutes for crystal violet.     

The Mechanism of the Gram Reaction I. The Specificity of the Primary Dye

Dyes of all major types were tested for their suitability as the primary dye in the Gram stain. When a counterstain was not used, some dyes of all types were found to differentiate Gram-positive from Gram-negative organisms. When a counterstain was used, these dyes were found to vary greatly in their suitability. Those dyes found to be good substitutes for crystal violet were: Brilliant green, malachite green, basic fuchsin, ethyl violet, Hoffmann's violet, methyl violet B, and Victoria blue R. All are basic triphenylmethane dyes. Acid dyes were generally not suitable. Differences in the reaction of Gram-positive and Gram-negative cells to Gram staining without the use of iodine were observed and discussed but a practical differentiation could not be achieved in this manner. Certain broad aspects of the chemical mechanism of dyes in the gram stain are discussed.     

Basic Fuchsin-Crystal Violet; A Rapid Staining Sequence for Juxtaglomerular Granular Cells Embedded in Epoxy Resin

A basic fuchsin-crystal violet staining sequence for demonstration of juxtaglomerular granular cells in epoxy-embedded tissues is rapid and results in slides with excellent contrast and intensity. Procedure: Cut sections 0.3-0.6 μ thick. Hydrate through xylene and alcohol to water. Stain in modified Goodpasture's stain (basic fuchsin, 1; aniline, 1; phenol, 1; 30% alcohol, 100) for 20-30 sec; rinse in tap water; stain in modified Stirling's (crystal violet, 5; alcohol, 10; aniline, 2; water, 88) for 20-30 sec; rinse in tap water and dry on a hotplate; mount in a synthetic resin. Granular cells of the juxtaglomerular apparatus are stained an intense dark blue by the crystal violet. Arterial elastic membranes and collagen are pale blue. Other structures are shades of red.     

Elastic Tissue Staining

It has been found that the addition of dextrin to samples of crystal violet and basic fuchsin employed in the prepararation of the elastic tissue stain after the technic of Weigert makes more sure a satisfactory final product. A modification of the original Weigert technic employing crystal violet or a mixture of crystal violet and basic fuchsin is offered as providing a better color contrast both visually as well as photographically. Crystal violet alone affords a bright greenish-yellow elastin while the addition of basic fuchsin results in a darker stain shading into dark blue as the proportion of basic fuchsin is increased.     

Contribution to the Staining of Neuroglia

The chemistry of Weigert's glia staining method is critically discussed. An investigation of the Heidelberger Victoria blue staining method has shown that Victoria blue may be replaced by other phenylmethane dyes as methyl violet, ethyl violet, and crystal violet. It was found that the exposure of the stained section to sunlight is an oxidation process. Artificial ultra violet rays or chemical oxidation agents give the same effect. Frozen sections fixed in formalin or alcohol may be stained in a concentrated aqueous solution of any of the above mentioned phenylmethane dyes, dried, and exposed to ultra violet rays for 30 minutes, then treated with 1/10 N. iodine solution, differentiated in xylol anilin and cleared in xylol. The glia cell body as well as the fibrils are clearly differentiated from the nervous elements and connective tissue.     

Stain Solubilities Part 1. Data in the Literature

The rather meager data found in the literature concerning the solubilities of the dyes used as biological stains is reviewed. Solubility data have been found concerning the following dyes: picric acid, martius yellow, crystal ponceau, methyl orange, tropaeolin O, orange II, Bismarck brown, Congo red, auramine, malachite green, fuchsin, methyl violet, gentian violet, crystal violet, methyl green, diphenylamine blue, aurin, corallin, phenolphthalein, flluorescein, eosin Y, iodo-eosin, methylene blue, alizarin, indigo carmine, and carmine. Much of this information is of questionable reliability. The writer is investigating the matter and his original data are to appear in subsequent papers.     

Stain Solubilities Part 1. Data in the Literature

The rather meager data found in the literature concerning the solubilities of the dyes used as biological stains is reviewed. Solubility data have been found concerning the following dyes: picric acid, martius yellow, crystal ponceau, methyl orange, tropaeolin O, orange II, Bismarck brown, Congo red, auramine, malachite green, fuchsin, methyl violet, gentian violet, crystal violet, methyl green, diphenylamine blue, aurin, corallin, phenolphthalein, flluorescein, eosin Y, iodo-eosin, methylene blue, alizarin, indigo carmine, and carmine. Much of this information is of questionable reliability. The writer is investigating the matter and his original data are to appear in subsequent papers.     

The Germicidal Effect of Staining Solutions

Gentian violet, crystal violet and carbol fuchsin applied to cover slip preparations for one minute will destroy the majority of non-spore-forming bacteria and yeasts, tho they can not be relied upon to do this consistently and in all cases.

The Gram staining procedure is more effective and non-spore-formers were never found to survive this process.

Methylene blue stains exert very little if any germicidal power and most organisms survived them readily. India ink was totally ineffective.

Several species of yeasts and yeast-like molds were killed in every instance by the Gram stain, gentian violet, crystal violet and carbol fuchsin, but survived both Loeffler's methylene blue and a plain aqueous solution of methylene blue.     

Basic Fuchsin as an Indicator in Endo's Medium

The writer has made an investigation of various samples of basic fuchsin for use in the Endo medium for differentiating the bacteria of the colon-typhoid group. Various different concentrations of the fuchsin samples have been used in making the media. The conclusions are as follows:

American made fuchsins differ markedly in their alcohol solubility properties. They contain materials which are very readily soluble in 95% alcohol, but which are precipitated by sodium sulphite.

This precipitation may be prevented by increasing the dilution of the fuchsin in alcohol.

In order to secure more dependable results in the use of decolorized basic fuchsin as an indicator in Endo Agar, it is advisable to test the fuchsin in different dilutions in alcohol in order to secure a completely decolorized solution. It is also advisable to carefully test those fuchsins which decolorize only in high dilutions with a known organism in Endo agar before relying on it as a satisfactory indicator for the presence of sewage organisms.     

Further Studies on a Modification of the Gram Stain

In perfecting the modification of the Gram-stain previously proposed, the following points are of interest:

1. Acetone is too strong a decolorizer for Gram-positive organisms and alcohol too weak for Gram-negative organisms. Consequently, it is now recommended that equal parts of acetone (100% c.p.) and ethyl alcohol (95%) be used as a decolorizing agent. The time of application should not ordinarily exceed 10 seconds.

2. Aqueous basic fuchsin (0.1%) serves as a strongly contrasting counterstain. Prolonged application renders Gram-positive organisms doubtful or Gram-negative, while short application renders Gram-negative organisms doubtful or Gram-positive. Twenty (20) seconds is therefore recommended as the time of application of the counterstain.

3. The method here described, with due regard for its limitations, is of value in Gram-staining pure or mixed cultures as well as for organic materials, such as Acidophilus milk, feces, etc., either for research purposes or classroom use. The method is as follows:

Air-dry film and fix with least amount of heat necessary.

Flood with dye for 5 minutes. Previously mix 30 drops of a 1% aqueous solution of crystal violet or methyl violet 6B with 8 drops of a 5% solution of sodium bicarbonate. Allow the mixture to remain for 5 minutes or more.

Flush with iodine solution for 2 minutes. Two grams iodine dissolved in 10 cc. normal sodium hydroxide solution and 90 cc. water added.

Drain without blotting but do not allow film to dry.

Add a mixture of equal parts of acetone and alcohol drop by drop until the drippings are colorless. (10 seconds or less.)

Air-dry slide.

Counterstain for 20 seconds with 0.1% aqueous solution of basic fuchsin.

Wash off excess stain by short exposure to tap water and air-dry. If slide is not clear immersion in xylol is recommended.     

The Germicidal Effect of Staining Solutions

Gentian violet, crystal violet and carbol fuchsin applied to cover slip preparations for one minute will destroy the majority of non-spore-forming bacteria and yeasts, tho they can not be relied upon to do this consistently and in all cases.

The Gram staining procedure is more effective and non-spore-formers were never found to survive this process.

Methylene blue stains exert very little if any germicidal power and most organisms survived them readily. India ink was totally ineffective.

Several species of yeasts and yeast-like molds were killed in every instance by the Gram stain, gentian violet, crystal violet and carbol fuchsin, but survived both Loeffler's methylene blue and a plain aqueous solution of methylene blue.     

Acid Fuchsin as a Stain—A Refinement in Manufacture

From the study of 38 samples of acid fuchsin prepared from several types of basic fuchsin and under varying conditions it is found that rosanilin sulfonated between 80° and 85°C. gives the best results in the Van Gieson staining technic. Staining tests also show that a satisfactory acid fuchsin will give the best results when employed with picric acid in the ratio of 1 part of the 1 per cent aqueous acid fuchsin to 20 parts of the aqueous picric acid. Details for the preparation and use of acid fuchsin are given.     

The Nature of Mycobacterial Acid-Fastness

Phenol is not essential to acid-fast staining, for it will occur in the absence of phenol where such lipoid-soluble basic dyes as night blue, Victoria blue B or Victoria R are used; it is essential for acid-fast staining with water soluble basic dyes such as basic fuchsin. When phenol is added to the staining solution, such water soluble basic dyes behave in effect like their lipid-soluble counterparts. The loss of mycobacterial acid-fastness with carbolfuchsin after bromination or chromation indicates that this phenomenon is related to the presence of unsaturated lipids in the bacterial cells. Within the cells these acid-fast lipids are bound in such a way that they are easily removed from all mycobacteria by hot dilute HCl; from leprosy bacilli alone they are easily removed with hot pyridine. From the results of various blocking reactions it appears that carboxyl and especially hydroxyl groups of these cellular lipids are essential to the acid-fast reaction of mycobacteria.     

Chemical structures and staining mechanisms of Weigert's resorcin-fuchsin and related elastic fiber stains

Chemical properties of Weigert's resorcin-fuchsin, orcinol-new fuchsin, Sheridan's crystal violet and their resorcinol-free analogues were investigated using reverse-phase and gel filtration chromatography, electrophoresis, and visible light spectroscopy. Their staining properties were also studied. It was concluded that 1) the staining components of Weigert's resorcin-fuchsin, orcinol-new fuchsin and their resorcinol-free analogues are all indamine oligomers, 2) resorcinol is required for the production of Sheridan's crystal violet, the staining components of which consist of crystal violet substituted by varying numbers of resorcinyl substituents, 3) the staining components of all preparations are cationic (i.e., basic) dyes, 4) iron is present in staining solutions as the tetrachloroferrate anion (FeCl4-) and not as Fe or as a dye-chelate, and 5) since even the smallest Weigert's resorcin-fuchsin, orcinol-new fuchsin or Sheridan's crystal violet component has a conjugated bond number of 32, the observed staining of elastic fibers is only as expected.     

The nature of mycobacterial acid-fastness.

Phenol is not essential to acid-fast staining, for it will occur in the absence of phenol where such lipoid-soluble basic dyes as night blue, Victoria blue B or Victoria R are used; it is essential for acid-fast staining with water soluble basic dyes such as basic fuchsin. When phenol is added to the staining solution, such water soluble basic dyes behave in effect like their lipid-soluble counterparts. The loss of mycobacterial acid-fastness with carbol-fuchsin after bromination or chromation indicates that this phenomenon is related to the presence of unsaturated lipids in the bacterial cells. Within the cells these acid-fast lipids are bound in such a way that they are easily removed from all mycobacteria by hot dilute HCl; from leprosy bacilli alone they are easily removed with hot pyridine. From the results of various blocking reactions it appears that carboxyl and especially hydroxyl groups of these cellular lipids are essential to the acid-fast reaction of mycobacteria.