Mechanisms of chromation hematoxylin stains

Summary In chromation hematoxylin sequence stains of Weigert-Smith-Dietrich type an exploration is presented of the nature of chromium binding tissue end groups, of the valency of the bound chromium and of the mechanisms and conditions of its binding.At 2–4° C prolonged (2–8 weeks) mordanting in 2.5% K₂Cr₂O₇ at pH 3.5 engenders staining with acetic hematoxylin essentially limited to histochemical ethylenic sites, completely preventable by prior aqueous bromination and unaffected by sulfation or acetylation. Erythrocytes, myelin and bile casts are examples of reactive tissue elements. At 24° C and more so at 60° C there is increased reaction of muscle, cytoplasm, nuclei and other structures; the reaction is now partially blocked by acylations and is only partly prevented by bromination, indicating participation of hydroxyl groups. Deamination decreases reaction at 60° C of protein background, but not notably of myelin, erythrocytes, or bile casts. The previously reported carboxyl binding of hot chromation oxyphilia is almost inapparent when chromation is done at 3° C. Chromic acid is less selective in its action, producing some background staining even at 3° C; K₂CrO₄ engenders no acetic or neutral hematoxylin staining, even at 6.6% and 24 hour mordanting at 24° or 60° C.Chromium deposited from dichromate or chromic acid mordanting reacts with hematoxylin solutions at pH 2.5 to 7.0, that deposited from Cr III salts reacts only at pH 6–7. Mordanting with Fe III, Fe II, Cu II and Sn II salts yields hematoxylin staining respectively from pH 2.5, 4.0, 5.0 and 2.5 upward. After K₂Cr₂O₇ mordanting brief reductions and acid treatments restrict hematoxylin staining to the same neutral pH zone as that produced after Cr III mordanting, but the pH 7 staining capacity of Cr deposited from K₂Cr₂O₇ is more resistant to extraction agents than that from Cr III solutions. It is therefore concluded that the chromium deposited in dichromate mordanting is of a higher valency than Cr III and it is suggested that Cr IV is present and bound to double bond sites in ring esters in the same manner as has been formulated for Mn and Os in the attack of KMnO₄ and OsO₄ on ethylene double bonds.Supported by National Cancer Institute Grant No. C-4816, National Institutes of Health, Bethesda, Maryland. Presented in part at the Third International Congress for Histochemistry and Cytochemistry, New York 1968.     

Ultrastructure of the nuclear apparatus of the lower ciliateRemanella granulosa Kahl (Karyorelictida)

Summary The nuclear apparatus ofRemanella granulosa has been investigated using conventional TEM methods and Bernhard's technique of preferential RNP staining. This species has two (rarely three) macronuclei and a single micronucleus (rarely two micronuclei). The nuclei always form a single group.The macronuclei contain a fibro-granular matrix resistant to EDTA destaining, and several nucleoli and chromatin bodies. The chromatin bodies are readily bleached with EDTA and are often clustered, or even fused, forming chromocenters. The nuclei are of the compact concentric type. Some macronuclei contain nuclear bodies, as finely fibrous spheres or bundles of coarse fibers, or both. Neither type of nuclear body is destained with EDTA. The spheres are frequently associated with nucleoli. There is no evidence of any transition between the two types of nuclear bodies. The macronuclear envelope contains numerous pore complexes and is strengthened with an electron dense layer. The micronucleus is filled with spongy condensed chromatin and surrounded by an envelope with occasional pores. This nucleus lacks nucleoli and nuclear bodies.     

Hematoxylin as a Pituitary Stain

The accurate picture of the acidophil granules of the anterior pituitary which is provided by iron hematoxylin can be combined with the differential staining of the basophils by either the periodic acid-Schiff (PAS) or combined aldehyde-fuchsin-PAS procedures. To accomplish this the two stages of the iron hematoxylin technique are separated so that mordanting in iron alum precedes and application of hematoxylin follows the basophil procedures.     

Fine structure and cytochemistry of the nuclei of the primitive ciliateTracheloraphis crassus (Karyorelictida)

Summary The nuclei ofTracheloraphis crassus were studied using light and electron microscopy combined with Bernhard's RNP staining and pronase digestion. The nuclear apparatus of this species consists of a longitudinal row of 11–43 macronuclei and 4–16 micronuclei. Like in all karyorelictids, the macronuclei are unable to divide and become segregated during cytokinesis; their number is supplemented in every cell cycle by differentiation of several new macronuclei from micronuclei.Each adult macronucleus contains a single compact endonuclear aggregate of several large chromocenters, readily destained with EDTA, and several RNP containing nucleoli. There is continuity between the material of the chromocenters and the decondensed DNP fibrils in the nuclear matrix. The nucleoli contain NORs in the form of fibrillar centers. The endonuclear aggregate includes also groups of RNP granules which are especially resistant to EDTA destaining. A microfibrillar sphere, usually localized at the periphery of the aggregate, contacts one or several nucleoli. The sphere is not bleached with EDTA, and only its periphery becomes digested with pronase. The macronuclear matrix consists of both protein fibrils and pronase-resistant fibrils, the latter being localized at the nuclear periphery.Developing macronuclear primordia contain loose strands of decondensed chromatin; only later they form chromocenters and nucleoli.The micronuclei reproduce by mitosis with typical chromosomes (2n=66). During interphase, they are filled with condensed chromatin which can be bleached with EDTA; they form no nucleoli. Ring-like lamellae, existing in the cavities of the chromatin mass, stain for RNA (after Bernhard) and are pronase-sensitive. These lamellae resemble the kinetochore material conserved during interphase in another karyorelictid ciliate,Trachelocerca geopetiti.     

Formalin-Pyrogallol As A Fixative For Plant Cytoplasm

Specimens of plant material 5.0 mm. thick or thinner were fixed 12-24 hours in a mixture of 10% commercial formalin 100 ml.; N NaOH, 1 ml. and pyrogallol 7 g. Histologic results obtained after paraffin embedding, mordanting of sections 24 hours in 2% ferric alum and hematoxylin staining indicated that the fixation was especially good for cytoplasmic structures.     

Simultaneous quantification of nucleoproteins and comparison of methyl green-pyronin Y and Feulgen staining in sections of oral squamous cell carcinoma,dysplastic lesions and normal mucosa

A fundamental difference between normal cells and tumor cells is the proliferative activity of the nucleus and nucleolus, which increases progressively from normal to oral dysplastic mucosa to oral squamous cell carcinoma (OSCC). This activity is evaluated routinely using hematoxylin and eosin (H & E) staining, but in some cases, inter-observer variability occurs among pathologists. We evaluated cellular proliferation by staining sections with the methyl green-pyronin Y procedure and the Feulgen reaction. We also compared the efficacy of methyl green-pyronin Y and Feulgen staining for studying nuclear and nucleolar features in oral dysplastic mucosa and in different grades of OSCC. Sections cut from formalin fixed, paraffin embedded blocks of five normal mucosa, 15 dysplastic mucosa, 10 well-differentiated OSCC, 10 moderately differentiated OSCC and five poorly differentiated OSCC cases were stained with Hematoxylin and Eosin, methyl green-pyronin Y and the Feulgen reaction. The mean diameters of the nuclei and number of nucleoli showed significant differences. A progressive increase in diameter of the nucleus and number of nucleoli was observed from normal mucosa through poorly differentiated OSCC. We observed that methyl green-pyronin Y stain is more useful than Feulgen and hematoxylin and eosin for simultaneous quantitative assessment of both RNA and DNA. The simplicity of this technique makes it a valuable tool even for daily routine examination.     

Immunolocalization of Ku-proteins (p80/p70): Localization of p70 to nucleoli and periphery of both interphase nuclei and metaphase chromosomes

Distribution on both nuclei and metaphase chromosomes of Ku-proteins, recognized by autoantibodies from a patient with systemic lupus erythematosus, has been studied using a specific monoclonal antibody (mAbH6) that recognizes p70, one Ku-protein. Observation with either a conventional fluorescent microscope or a confocal laser scanning microscope revealed mAbH6-stained p70 antigen localized on both nuclear periphery and nucleoli of human interphase cells. The specific staining of nucleoli with mAbH6 has been confirmed using isolated nucleoli from rat liver in which the staining was seen as fine granules surrounding nucleolar DNA. During mitosis p70 antigen moved away from association with the nuclear envelope region to localization on the periphery of condensed chromosomes with no apparent staining of chromosome interior. The p70 antigen was copurified with DNA fragments by immunoaffinity column chromatography using mAbH6. The mAbH6 staining of both nuclear periphery and nucleoli was lost upon digestion with DNase I at low concentrations. These results suggest that p70 antigen is connected with these nuclear structures through DNA.     

New fluorescence reactions in DNA cytochemistry. 2. Microscopic and spectroscopic studies on fluorescent aluminum complexes

Metal-dye complexes are widely applied in light microscopic techniques for chromatin staining (e.g., hematoxylin and carmine), but fluorescent complexes between phosphate-binding cations and suitable ligands have been little used. Preformed and postformed Al complexes with different anionic dyes induced strong and selective fluorescence reactions in nuclei from chicken blood smears, frozen sections, paraffin-embedded sections and Epon-embedded sections of mouse and rat tissues, mitotic chromosomes, meiotic chromosomes and kinetoplasts of Trypanosoma cruzi epimastigotes. The DNA-dependent fluorescence of these structures showed a very low fading rate. The emission colors were related to the ligand. The most suitable compounds for forming fluorescent Al chelates were 8-hydroxyquinoline, morin, nuclear fast red and purpurin. Staining with diluted carmine solutions and InCl3 mordanting, followed by 8-hydroxyquinoline, also induced chromatin fluorescence. After treating isolated mouse chromosomes with the preformed complex Al-nuclear fast red, x-ray microanalysis indicated a P:Al:dye binding ratio of about 40:15:1. The selectivity, stability and easy formation of these fluorescent Al complexes are obvious advantages for their use as new cytochemical probes in cytologic studies.     

Differential Nucleolar Staining Affinity with a Modified Papanicolaou Staining Procedure

A modified Papanicolaou staining procedure using diluted Harris' hematoxylin with potassium alum is described. Nucleolar staining varies from blue to bright red. This technique has been applied to mammary tumor cell lines in vitro under several conditions of hormonal stimulation known to induce protein synthesis and cell differentiation. Blue nucleoli are observed in control resting cells, while bright red nucleoli are seen after hormonal stimulation.     

Characterization of restriction nuclease prepared chromatin by electron microscopy

Chromatin was solubilized from rat liver nuclei by digestion with the restriction nuclease EcoRI or HaeIII in the presence or absence of EDTA and sodium chloride. The samples were investigated by electron microscopy after positive and negative staining with uranyl acetate under a number of conditions. Depending on the salt concentration during solubilization the chromatin appeared as beads on the string or in more compact form. Solenoid- and superbead-like structures were seen as had been reported for chromatin solubilized with micrococcal nuclease.     

An Azocarmine stain for Differential cell Analysis of the rat Anterior Hypophysis

A method of staining is described which is especially designed to facilitate differentiation of the cell types of the rat anterior hypophysis. Fixation in Zenker-formol solution is recommended. Pre-staining of the nuclei by a short immersion in alum hematoxylin is followed by mordanting in anilin alcohol and a 45 minute period of staining in azocarmine solution at 60d`C. The counterstains, acid green and orange G, are dissolved in clove oil to avoid destaining of the azocarmine.     

The effect of the Bacillus thuringiensis exotoxin on the fine nucleolar morphology and ultrastructure

Depending on the dose administred to the experimental mice, the Bacillus thuringiensis exotoxin produces striking changes in the nucleolar morphology of hepatocytes such as the formation of ring-shaped nucleoli, micronucleoli and the segregation of nucleolar components. Such changes are apparently related to the decrease and inhibition of nucleolar biosynthetic activities in the production of the nucleolar RNA. In addition, the Bacillus thuringiensis exotoxin causes the formation of nucleolar peripheral dense plaques and, at higher concentrations, the segregation of two distinctly separated granular areas in the nucleolus. Both these light and dense granular areas showed positive staining with Bernhard's EDTA procedure for the preferential demonstration of RNA-containing structures. In some segregated nucleoli the granular components of light granular areas seemed to leave the nucleolus. The presence of discontinuous filamentous shell around micronucleoli produced by the high dose of exotoxin suggests the nucleolar origin of nuclear granular bodies which are surrounded by similar but continuous filamentous shell characteristic of these structures.     

Phosphotungstic Acid-Hematoxylin; Spectropho-Tometry of the Lake in Solution and in Stained Tissue

Job's method of continuous variation (Ann. Chim., ser. 10; 9, 113-203, 1928) was applied to tungstate-hematein and molybdate-hematein lakes. For phosphotungstic acid-hematein (PTA-Hn), sodium tungstate-hematein, or molybdic acid-hematein, it demonstrates that each forms a single complex in solution, with ratios of composition (PTA to Hn) 1:2, 1:2 and 1:1 respectively. PTA-Hn was the best stain, as judged by its ability to differentiate collagenous connective tissues from muscle, and to delineate nuclear and cytoplasmic detail. Hematein is used in place of hematoxylin because a reproducible, potent staining solution can be prepared without lengthy aging periods or uncertain oxidants. With this lake, staining is independent of fixation and obviates the necessity of mordanting procedures prior to staining. Microspectrophotometric evidence indicates that the blue component of the well-recognized polychromasia of these lakes is a true example of bathochromic metachromasia. Staining by the lake at various pH values and by acid and basic dyes after PTA treatment of tissues indicate that PTA-Hn is an acid lake dye and therefore different from the iron and aluminum hematoxylin lakes. Observations on the distribution of metachromasia suggest that it is topographically related to tissue components having a high content of basic protein.     

INTRAMITOCHONDRIAL FIBERS WITH DNA CHARACTERISTICS : I. Fixation and Electron Staining Reactions

Chick embryo mitochondria, studied with the electron microscope, show crista-free areas of low electron opacity. These areas are observable after fixation with osmium tetroxide, calcium permanganate, potassium permanganate, formaldehyde, acrolein, acrolein followed by osmium tetroxide, uranyl acetate followed by calcium permanganate, and acetic acid-alcohol. Staining of sections with lead hydroxide or uranyl acetate, or with both, resulted in an increased density of a fibrous material within these areas. The appearance of the fibrous structures varied with the fixative employed; after fixation with osmium tetroxide the material was clumped and bar-like (up to 400 A in diameter), whereas after treatment of osmium tetroxide-fixed tissues with uranyl acetate before dehydration the fibrous structures could be visualized as 15 to 30 A fibrils. Treatment with ethylenediaminetetraacetate (EDTA) in place of uranyl acetate coarsened the mitochondrial fibrils. After fixation with calcium permanganate or potassium permanganate, or a double fixation by uranyl acetate followed by calcium permanganate, the fibers appeared to have a pattern and ultrastructure similar to that observed after the osmium tetroxide-uranyl acetate technique, except that some of them had a slightly greater diameter (up to 50 A). Other fixatives did not preserve the fibers so well. The fibers appeared strongly clumped by formaldehyde fixation, and were difficult to identify after fixation with acrolein or acetic acid-alcohol. The staining of nucleic acid-containing structures by uranyl acetate and lead hydroxide was improved by treatment of osmium tetroxide-fixed sections with hydrogen peroxide, and the mitochondrial fibers also had an increased density in the electron beam after this procedure. The staining characteristics suggest the fibrous material of chick embryo mitochondria to be a nucleic acid-containing structure, and its variable appearance after different fixations parallels that previously reported, or described in this paper, for the nucleoplasm of bacteria and blue-green algae. The results, in addition to those described in the accompanying communication, indicate that these mitochondria contain DNA.     

Simultaneous demonstration of glycogen and protein in glycosomes of cardiac tissue

Cardiac conduction fibers fixed either in glutaraldehyde and OsO4 or treated additionally en bloc with uranyl acetate were studied in order to demonstrate the structure of glycosomes (protein-glycogen complex). Sections were stained histochemically by periodic acid-thiosemicarbazide-silver proteinate (PA--TSC--SP) for glycogen followed by uranyl acetate and lead citrate (U-Pb) for protein. In control sections periodic acid was replaced by hydrogen peroxide (H2O2). Glycogen appeared in all sections stained by PA-TSC-SP. Protein was poorly contrasted in periodic acid treated histochemical sections taken from fixed in glutaraldehyde and OsO4. Simultaneous staining of glycogen and protein was achieved in sections of tissue treated en bloc with uranyl acetate. This treatment revealed two classes of glycosomes: 1) glycosomes deposited freely in the cytoplasm whose structure was disintegrated after treatment with uranyl acetate: 2) glycosomes associated with other cellular structures that remained intact. Staining of glycogen and protein in the same section demonstrated for the first time the structure of intact glycosomes.     

Standardization of the Papanicolaou stain. I. A comparison of five nuclear stains.

The staining characteristics of five nuclear stains used in a Papanicolaou staining procedure were investigated. Alcohol-fixed cervical smears were stained with a modified Papanicolaou procedure using hematoxylin, alcoholic thionin bromide, alcoholic Victoria blue B, gallocyanin or the thionin Feulgen reagent (thionin-SO2) as the nuclear stain. The same anionic counterstain was used for all slides, and the optical densities of cell nuclei and cytoplasm were measured with the IBAS 2000 image analyzer. Alcoholic thionin gave the most intense nuclear stain, with a very high reproducibility of the staining pattern. Hematoxylin showed the highest coefficient of variation of the staining intensity. Both hematoxylin and gallocyanin gave some nonspecific cytoplasmic staining. Thionin-SO2 allowed a quantitative assessment of DNA, but gave a low staining intensity. Staining with the metal complex dyes interfered with subsequent staining with the pararosaniline Feulgen reagent. Alcoholic thioinin is thus recommended as a nuclear stain for cervical cytology in the Papanicolaou procedure, both for image analysis and for visual microscopy.     

Acridine Orange—Methyl Green Fluorescent Staining of Nucleoli

The staining of nucleoli with the fluorescent dye acridine orange followed by counter-staining with methyl green differentially stained nucleoli in both plant and animal cells. The nucleoli fluoresced as bright structures highlighted against the quenched fluorescence of the chromatin. This technique provides a simple and highly reproducible method for differential staining of nucleoli.     

Nuclear localization of Semliki Forest virus-specific nonstructural protein nsP2.

About 50% of Semliki Forest virus-specific nonstructural protein nsP2 is associated with the nuclear fraction in virus-infected BHK cells. Transport into the nucleus must be specific, since only trace amounts of nsP3 and nsP4 and about 13% of nsP1, all derived from the same polyprotein, were found in the nucleus. Subfractionation of [35S]methionine-labeled Semliki Forest virus-infected cells showed that 80 to 90% of the nuclear nsP2 was associated with the nuclear matrix. Indirect immunofluorescence, with anti-nsP2 antiserum, showed the most intensive staining of structures which by Nomarski optics appeared to be nucleoli. In the presence of 1 to 5 micrograms of dactinomycin per ml the nuclei were stained evenly and no nucleoli could be found. Transport of nsP2 into the nucleus occurred early in infection and was fairly rapid. A cDNA encoding the complete nsP2 was isolated by the polymerase chain reaction technique and ligated into a simian virus 40 expression vector derivative. When BHK cells were transfected with this pSV-NS2 vector by the lipofection procedure, nsP2 was expressed in about 1 to 5% of the cells, as shown by indirect immunofluorescence. In positively transfected cells the immunofluorescence stain was most intensive in the nucleoli. Thus, Semliki Forest virus-specific nsP2 must have information which directs it into the nuclear matrix and, more specifically, into the nucleoli.     

A feulgen-positive nucleolus

The Feulgen and Rossenbeck staining procedure reveals in all embryonic and adult cell types of the quail (Coturnix coturnix japonica) one or several chromatin condensations in the interphase nucleus. The Unna-Pappenheim technique, combined with RNAase treatment according to Brachet, shows that these chromatin masses are associated with the nucleolar RNA. Electron microscopic studies confirm this observation and the EDTA preferential staining procedure for RNP according to Bernhard makes it possible to distinguish three main types of nucleoli in the various tissues of the quail showing different patterns of RNA and DNA relationships. The functional significance of the large amount of nucleolus-associated chromatin in the quail, and of the more or less intimate relationships between RNA and DNA in the various types of nucleoli are discussed.