A new method for transfer of polyethylene glycol-embedded tissue sections to silanated slides for immunocytochemistry

Polyethylene glycol (PEG) is an excellent embedding medium for immunohistochemical studies. It provides structural preservation superior to frozen sections and increased sensitivity of antigen detection compared with paraffin sections. One limitation of PEG embedment is that PEG sections are difficult to handle and adhere poorly to glass slides. Here we present a simple and effective method for embedding tissues in PEG and transferring the resultant sections onto silanated glass slides. In addition, a method for silver enhanced colloidal gold immunostaining was combined with common dye staining to demonstrate the excellent structure preservation and sensitive antigen detection. Bovine chorionic membrane was fixed with Bouin's fixative, embedded in polyethylene glycol (PEG) 1500, cut into 5-microns sections, flattened over agarose blocks (10 x 10 x 2 mm3), and blotted onto Digene silanated slides. Slides were then washed in PBS, which removed the PEG and agarose blocks. Tissue sections were immunocytochemically stained with dilute antiserum raised in a rabbit against purified bovine placental retinol binding protein (bpRBP). Sections were washed and incubated with 1-nm colloidal gold-labeled goat anti-rabbit IgG. The immunogold particles were enhanced by silver staining (IGSS). Specimens were observed and photographed with an Olympus epipolarization microscope. The new method offered excellent morphological preservation of cell structure and the epipolarization microscopy provided high sensitivity for detection of specific immunogold-silver particles.     

A new technique for staining mast cells using ferroin

We describe here a new method for specific staining of mast cells using ferroin. Different hamster tissues were fixed in 4% formalin and processed for paraffin embedding. Sections were stained with hematoxylin followed by ferroin acidified with 2.5 N sulfuric acid to pH 4.0. Mast cells stained an intense orange color that contrasted markedly with bluish violet nuclei. High contrast was also observed when ferroin colored sections were counterstained with light green instead of hematoxylin. To evaluate the specificity of the stain, hamster cheek pouch sections were stained with toluidine blue, alcian blue-safranin O, and ferroin. Quantitative evaluation of mast cells stained with the three techniques showed no statistical difference. The simplicity and selectivity of this method is sufficient for image analysis of mast cells.     

A new technique for staining mast cells using ferroin

We describe here a new method for specific staining of mast cells using ferroin. Different hamster tissues were fixed in 4% formalin and processed for paraffin embedding. Sections were stained with hematoxylin followed by ferroin acidified with 2.5 N sulfuric acid to pH 4.0. Mast cells stained an intense orange color that contrasted markedly with bluish violet nuclei. High contrast was also observed when ferroin colored sections were counterstained with light green instead of hematoxylin. To evaluate the specificity of the stain, hamster cheek pouch sections were stained with toluidine blue, alcian blue-safranin O, and ferroin. Quantitative evaluation of mast cells stained with the three techniques showed no statistical difference. The simplicity and selectivity of this method is sufficient for image analysis of mast cells.     

Immunohistochemical staining on hydroxyethyl-methacrylate-embedded tissues

Hydroxyethyl-methacrylate (GMA) embedding has recently been proposed for light microscopy studies. In the present investigation extracellular protein antigens were localized on GMA-embedded renal biopsy tissue. Conventionally frozen sections were compared with GMA sections from 55 renal specimens for the detection of extracellular protein antigens. Sections were directly stained with fluorescein- or peroxidase-conjugated antisera against immunoglobulin (Ig) G, IgA, IgM, C3, C1q, and fibrinogen. Results obtained using these two methods showed a 74-89% agreement, depending on the antigen under study. Some discrepancy between GMA and frozen sections was observed in three cases of renal amyloidosis and those cases presenting focal or trace reactions; the differences did not, however, influence the diagnosis. Prerequisites for antigen recovery on GMA sections were a) choice of fixative; b) abrupt dehydration of specimens; and c) treatment of sections with nonspecific protease. The improved localization and the lower background staining obtained led to easy and immediate detection of antigens on GMA sections despite the reduced antigenicity due to the embedding process.     

Improved Polyester Wax Embedding for Histology

Polyester waxes are fatty add esters of polyethylene glycol. Polyethylene glycol 400 distearate melts at 35°C, infiltrates tissues well, and sections readily at 2 μ to more than 30 μ. Sections 2 μ to 6 μ are more easily cut when a kitchen strainer full of solid CO₂ (dry ice) is mounted above the microtome to cool the block and the knife, and when the knife crosses the block very slowly. Ribbons are flattened in water at room temperature and are mounted conventionally. Polyester ribbons are somewhat stickier than paraffin ribbons. Polyethylene glycol 400 distearate is slightly hydrophilic; immediately after microtomy and before the ribbon is affixed to the microscope slide, sections in the wax ribbon may conveniently be stained with 0.05% toluidine blue in aqueous benzoate buffer, pH 4.4. Tissue structure is better preserved in polyester than in paraffin wax, probably because structural lipids are better retained and localized. However, this difference between waxes is slight if tissues are well fixed and dehydrated. Other advantages of polyester wax are that sections fragment less, hard tissues rarely split away from the wax ribbon, no static electricity is generated, and the microtome knife seems to remain sharp for a longer time.     

Immunocytochemical localization of pro gamma MSH, gamma MSH, ACTH and beta endorphin/beta lipotrophin in the fetal sheep pituitary: an ontogenetic study

An immunocytochemical staining technique was used to localize four fragments [pro gamma MSH, gamma MSH, ACTH and beta endorphin/beta lipotrophin (beta endorphin/beta LPH)] of the proopiomelanocortin molecule in both the adult and fetal sheep pituitary. In the adult sheep anterior pituitary each fragment was localized in cells that were darkly stained, stellate and widely distributed throughout the gland. The same cells, identified in three serial sections, stained with anti-pro gamma MSH, anti-ACTH and anti-beta endorphin/beta LPH. In the fetal sheep anterior pituitary all the proopiomelanocortin derived fragments were present at 38 days gestation. Between about 90 and 130 days of gestation both adult type proopiomelanocortin cells (small, stellate) and uniquely fetal cells (large, columnar) were present. Both adult-type and fetal proopiomelanocortin cells were identified in serial sections of the fetal anterior pituitary, stained with anti-pro gamma MSH, anti-ACTH and anti-beta endorphin/beta LPH. The adult intermediate lobe was immunoreactive with anti-pro gamma MSH and anti-beta endorphin/beta LPH but not with anti-gamma MSH or anti-ACTH. The fetal intermediate lobe was immunoreactive with all four antisera from 60 days gestation.     

Development of a simple embedding procedure allowing immunocytochemical localization at the ultrastructural level

Immunobed solution A is a water-soluble acrylic compound recently developed for immunocytochemical localization at the light microscopic level. In this study, we combined it with methyl methacrylate (MMA) to achieve sufficient hardness to obtain ultra-thin sections. Samples of platelets were dehydrated and embedded in the water-soluble acrylic mixture (WSAM). The embedding process was carried out at 4 degrees C and final polymerization was induced with either chemical (benzoyl peroxide) or physical (UV light) catalysts. Tubulin was localized at the ultrastructural level in sections embedded according to these two methods. Results were compared with those obtained in platelets processed in Lowicryl. Dehydration and embedding with the WSAM yielded a preservation of antigenicity similar to that obtained in Lowicryl. The new procedure benefits from the low temperature achieved during polymerization, providing good ultrastructural morphology and immunolocalization of protein antigens with the simplicity of a routine embedding procedure for light microscopy.     

New Fuchsin-Hematoxylin-Eosin; A Stain for Acid-Fast Bacilli and Surrounding Tissue

This is a staining technique for histopathologic evaluation of tissue reaction in the environs of acid-fast tubercle bacilli (avian and bovine) in sections. Fresh tissue is fixed in 10% neutral formalin and processed in the usual manner for embedding in paraffin. Sections are cut approximately 6 μ. thick, dewaxed, hydrated, and stained with Harris' hematoxylin. They are rinsed in tap water, differentiated in add alcohol, washed in tap water, given a distilled water rinse and stained at 20-30° C in a 1% solution of new fuchsin in 5% phenol. Each slide is then handled individually by placing it directly into a saturated aqueous solution of Li₂CO₃ and agitated gently for a few seconds. This is followed by differentiation with 5% glacial acetic acid in absolute or 95% ethyl alcohol until the color stops running. Two rinses in absolute or 95% ethyl alcohol follow. The sections are then counterstained in the color add of eosin Y prepared according to the method of Schleicher (Stain Techn., 28, 119-23, 1953) and used as an 0.025% solution in absolute alcohol. Following passage through 2 changes of absolute alcohol, the sections are cleared in xylene, then mounted in Permount or similar synthetic resin. The add-fast barilli are emphasized by their bright retractile red color within a contrasting background of hematoxylin and eosin.     

Staining of Different Tissues in Thick Epoxy Resin-Impregnated Sections of Human Fetuses

Sections of undecalcified human fetuses, fixed in formaldehyde, embedded in the epoxy resin Biodur E 12 and cut on a diamond-wire saw were stained according to a slight modification of the method described by Laczko and Levai. The sections were immersed in a methylene blue/azure II solution at 90 C for at least 3 min and counterstained with a basic fuchsin solution at the same temperature. Differential staining was as follows: bone stained pinkish; cartilage, violet; collagen fibers, blue-violet; elastic fibers, red and muscle fibers, green-blue. Most other tissues were stained blue-violet against the transparent background of the embedding epoxy resin. Thanks to the distinct and differential staining of each tissue, contrast is sufficient for black and white as well as for color photography.     

New Fuchsin-Hematoxylin-Eosin; A Stain for Acid-Fast Bacilli and Surrounding Tissue

This is a staining technique for histopathologic evaluation of tissue reaction in the environs of acid-fast tubercle bacilli (avian and bovine) in sections. Fresh tissue is fixed in 10% neutral formalin and processed in the usual manner for embedding in paraffin. Sections are cut approximately 6 μ. thick, dewaxed, hydrated, and stained with Harris' hematoxylin. They are rinsed in tap water, differentiated in add alcohol, washed in tap water, given a distilled water rinse and stained at 20-30° C in a 1% solution of new fuchsin in 5% phenol. Each slide is then handled individually by placing it directly into a saturated aqueous solution of Li₂CO₃ and agitated gently for a few seconds. This is followed by differentiation with 5% glacial acetic acid in absolute or 95% ethyl alcohol until the color stops running. Two rinses in absolute or 95% ethyl alcohol follow. The sections are then counterstained in the color add of eosin Y prepared according to the method of Schleicher (Stain Techn., 28, 119-23, 1953) and used as an 0.025% solution in absolute alcohol. Following passage through 2 changes of absolute alcohol, the sections are cleared in xylene, then mounted in Permount or similar synthetic resin. The add-fast barilli are emphasized by their bright retractile red color within a contrasting background of hematoxylin and eosin.     

Staining of different tissues in thick epoxy resin-impregnated sections of human fetuses

Sections of undecalcified human fetuses, fixed in formaldehyde, embedded in the epoxy resin Biodur E 12 and cut on a diamond-wire saw were stained according to a slight modification of the method described by Laczkó and Lévai. The sections were immersed in a methylene blue/azure II solution at 90 C for at least 3 min and counterstained with a basic fuchsin solution at the same temperature. Differential staining was as follows: bone stained pinkish; cartilage, violet; collagen fibers, blue-violet; elastic fibers, red and muscle fibers, green-blue. Most other tissues were stained blue-violet against the transparent background of the embedding epoxy resin. Thanks to the distinct and differential staining of each tissue, contrast is sufficient for black and white as well as for color photography.     

Staining of Different Endocrine Cells with Hydrochloric Acid-Toluidine Blue in Epon Embedded Rat Tissue

The usual HCl-toluidine blue staining of different endocrine cells is applicable to paraffin embedded material. A modification for Epon embedded tissue suitable for consecutive light and electron microscopic studies is described which makes it possible to find the same stained cell, both in a semithin section and in subsequent ultrathin sections. This method facilitates the search for scattered specific endocrine cells. Without removing the resin, sections of Epon embedded tissues were hydrolyzed for 17 hr in 1% HCl at 65 C and stained for 2 turn 0.1% toluidine blue in McIlvaine buffer, pH 5.8. The following cells were stained: C cells in thyroid glands; A and D cells in pancreatic islets; B cells in anterior pituitary; G, D and Ec cells in the gastrointestinal tract; Ad cells of the adrenal medulla.     

Differentiation of Myofibrillae, Reticular and Collagenous Fibrils in Vertebrates

A procedure for the differentiation of the mesenchymal derivatives, myofibrillae, reticular and collagenous fibers is presented. Formol-Zenker fixation (5-12 hours) is followed by the washing, iodinization, dehydration and paraffin embedding steps routine for that fixative with the following modifications. Zirkle's butyl alcohol series is used for dehydration and infiltration with paraffin as well as in the alcohol slide series. Embedding paraffin used is Parawax plus 8-10% bayberry wax. Tissue-exposed surface of paraffin block is soaked in water overnight before cutting serial sections at 3-5μ. Sections are mounted using the dilute albumen method, and the slides, thoroughly dried at 37^oC. overnight, are left at 60^o for 10 minutes to melt the paraffin of the sections. Before staining, the sections are given a preliminary treatment with potassium permanganate and oxalic acid. For reticular staining a 10% silver nitrate bath is succeeded by an ammoniacal silver carbonate solution followed by reduction in 1% neutral formalin, toning in gold chloride and fixing in sodium thiosulphate. Myofibrillae, the sacroplasmic limiting membrane and other sarcous elements are stained by Heidenhain's azocarmine solution, adult tissues at room temperature and fetal tissues at 50 ^oC. Differentiation in phosphotungstic acid is followed by the staining of collagenous fibers. For adult tissue, light green SF (C.C.) is used and for fetal tissue, fast green FCF (C.C). A discussion of the preparation of ammoniacal silver solutions is included. Both stock and used solutions of ammoniacal silver have been in use by the author for over a period of two years.     

A Tribasic Stain for Thin Sections of Plastic-Embedded, OsO4-Fixed Tissues

Thin (0.5-1 μ) sections of plastic-embedded, OsO₄-fixed tissues were attached to glass slides by heating to 70 C for 1 min. A saturated solution combining toluidine blue and malachite green was prepared in ethanol (8% of each dye) or water (4% of each dye). Methacrylate or epoxy sections were stained in the ethanol solution for 2-5 min. The water solution was more effective for some epoxy sections (10-80 min). Epoxy sections could be mordanted by 2% KMnO₄, in acetone (1 min) before use of the aqueous dye, reducing staining time to 5-10 min and improving contrast. Aqueous basic fuchsin (4%) was used as the counter-stain in all cases; staining time varied from 1-30 min depending upon the embedding medium and desired effects, methacrylate sections requiring the least time. In the completed stain, nuclei were blue to violet; erythrocytes and mitochondria, green; collagen and elastic tissue, magenta; and much and cartilage, bright cherry red. Sections were coated with an acrylic resin spray and examined or photographed with an oil-immersion lens.     

A Method for the Preparation of Undecalcified Bone Sections for Light Microscopy and Microradiography

A method which gives good quality 1-2 μm thick sections of undecaldfied cancellous and thin cortical bones for light miuoscopy is described. Formalin fixed material is dehydrated in graded acetones and embedded in a modiEed formula of Spurr's low viscosity embedding medium. After a 16 hour polymerisation period at 60 C, sections are cut at 1-2 μm thickness on a Porter-Blum JB4A rotary microtome Using glass knives. Sections are attached to clean glass slides with heat, the resin degraded in bromine vapour and removed in acetone. This allows comparative ease of staining. The technique is rapid, does not interfere with tetracycline fluorescence and the same specimens can be used to prepare thick sections for microradiography.     

A rapid and simple staining method, using Toluidine Blue, for analysing mitotic figures in tissue sections

Summary Mitotic index is a clinically important parameter in cancer pathology. We developed a staining method using Toluidine Blue to detect efficiently and rapidly mitotic figures in sections of formalin-fixed paraffin-embedded human and rat tisues. Sections were stained at acid pH with a 0.01% Toluidine Blue solution after removal of RNA with hydrochloric acid or ribonuclease. The optimal pH of the TB staining solution was found to be 4.5 for rat tissues and 3.5 for human tissues. This procedure stained mitotic figures much more intensely than other (extra)cellular structures. A quantitative estimate of the total number of nuclei in the field where mitotic figures were counted, was obtained in an adjacent section hydrolysed in 5 N hydrochloric acid and stained by the Feulgen reaction with a Schiff-type reagent containing 0.01% Toluidine Blue. This method specifically stained interphase and mitotic nuclei and the field cellularity could be quantified by image cytometry. When these procedures were performed on two consecutive serial sections, a mitotic index could be determined accurately by relating the count of mitotic figures to the number of tumour cells.     

Quantitative immunocytochemistry of pituitary receptors for luteinizing hormone-releasing hormone

In Araldite sections of male rat pituitaries, stained after embedding by the unlabeled antibody enzyme method with antisera to native luteinizing hormone-releasing hormone (LH-RH) or LH-RH azo-conjugated to bovine serum albumin, localization is confined mainly to the interior of the large, and to a lesser extent to that of the small, secretion granules of the gonadotrophic cells. Plasma membranes are not demonstrated. Except for weak staining in the granules of corticotrophs, no other pituitary cell is stained. Pretreatment of sections with LH-RH (to dilutions of 4 pg/mul) increases staining intensity in the gonadotrophic granules. Other cells are unaffected. The lesser the gonadotroph staining intensity without pretreatment, the greater the increase (more than 23-fold reactivity). Augmented staining is measurable (P less than 0.001) to antiserum dilutions of 1:240000. Pretreatment with des-Glu-1-LH-RH, porcine corticotropin or rat prolactin has no effect. LH-RH-Gly-10(des-amide) inhibits. Rat glycoprotein hormones enhance staining with anti-azo-conjugated LH-RH. With antinative LH-RH these hormones enhance weak staining, but inhibit strong staining. Thick vibrotome sections of male rat or rabbit pituitaries stained before embedding reveal specific localization on plasma membrane and gonadotrophic secretion granules provided the sections have been pretreated with LH-RH (250 pg/mul). The data show that LH-RH after reaction with receptor is not sterically hindered from binding specific antibodies. Receptor may be found in secretion granules, both in the free state or combined with LH-RH. Plasma membrane receptor, on the other hand, was free under the conditions of the experiments. Immunization with LH-RH elicits not only heteroimmune antibodies specific for LH-RH, but also a group of still ill defined autoimmune antibodies, some of which may conceivably be reactive with glycoprotein hormone alpha-chains.     

应用免疫胶体金技术定位感病大麦细胞中的大麦和性花叶病毒

本文报道免疫胶体金标记技术的建立,并用此技术定位大麦叶和根组织超薄切片中大麦和性花叶病毒(BaMMV)。在感染病毒的大麦叶和根细胞中,病毒束、游离病毒颗粒和病毒外壳蛋白多分布于细胞质丰富的细胞中,且以液泡和叶绿体(仅叶组织)周围较多。在细胞器已解体的病根表皮细胞中,有时也可检测到大量游离病毒粒子。少数风轮体或板状集结体上也存在病毒或病毒外壳蛋白。细胞核、叶绿体、线粒体、细胞膜以及其他细胞器上都未见有特异性金颗粒标记。     

Aminopeptidase activity of elastotic fibres--a histochemical artifact?

Synopsis Elastotic fibres of human skin and of elastofibroma were found to be stained when sections of these tissues had been incubated for aminopeptidase using leucine naphthylamide as substrate and Fast Blue B as the coupling agent. Sections that had been inactivated (with formalin or mercuric chloride) and partially covered with an intact kidney section were stained identically. A dialysing membrane placed between the inactivated skin section and the intact kidney section did not prevent staining of the elastotic fibres. The fibres were also stained when sections were incubated in an aqueous mixture of naphthylamine and an excess of Fast Blue B. It is concluded that the staining of elastotic fibres in histochemical amino-peptidase reactions may be due to adsorption of coloured azo derivatives and may not indicate enzyme activity in the fibres.     

Ultrastructure of B. pertussis using cryoultramicrotomy]

The authors pointed to a possibility of using the method of cryoultramicrotomy in studying the ultrastructure of Gram negative B. pertussis bacteria under the following conditions: a) fixationwith a 5% glutaraldehyde on cacodylate buffer (pH 7.5) for 30 min; b) replacement with a 30% dimethylsulfoxide in distilled water with a subsequent embedding of the material into tissue-tek; c) freezing in fluid nitrogen for 5 min; d) cutting at a temperature of -- 90% degrees C and at the temperature of glass knife of -- 40 degrees C, the knife angle of alpha = 45 degrees, beta = 6 degrees, and the cutting velocity of 5 mm/sec; e) placing of sections on copper grates covered with a 0.1% moulding membrane; d) contrasting with a 2% phosphotungstic acid queous solution (pH 7.5) for 5 sec and with a 3% uranil acetate on water for 5 min. Use of the mentioned method pemitted to detect structures localized in B. pertussis cytoplasm and also to trace the dynamics of their formation.