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At least 919 records · Page 51Linked to original sources
PubMed2000

[Electron immunohistochemical analysis of localization of neutral Mn2+-dependent DNAase. II. Analysis of ultrastructural localization in epon sections of different organs of the rat].

The use of a conjugate of colloidal gold with monotypic antibodies against a neutral Mn(2+)-dependent DNAse has revealed the enzyme localization in ultrathin Epon sections of glutaraldehyde fixed tissues. Technical procedures involved in fixation, embedding, and immune reactions are described. DNAse has been established in the nuclei in both normal and regenerating liver. A protein, immunologically close to DNAse, has been identified in the nuclei of a lymph node, thymus, spleen and cerebellar cortex.

Animals↗
PubMed1995

Glycol methacrylate embedding of alginate-polylysine microencapsulated pancreatic islets.

A method for processing and embedding alginate-polylysine microencapsulated pancreatic tissue in glycol methacrylate resin (GMA) is described. Fixation in 4% phosphate buffered formaldehyde, processing in ascending concentrations of glycol methacrylate monomer and embedding in Technovit 7100 results in well preserved morphological details of hydrogels, hydrogel-cell interfaces, and encapsulated pancreatic tissue. Routine staining with Loeffler's methylene blue, hematoxylin and eosin, and Romanovsky-Giemsa gave excellent images of the GMA embedded alginate polylysine membrane and tissues allowing cells on the outside of the capsule to be analyzed effectively as part of the foreign body reaction against the capsule membrane.

Alginates↗
PubMedDate not supplied

The application of AgNOR technique on glycol-methacrylate embedded human normal and pathological tissues.

The Authors have applied the AgNOR technique to a series of normal and pathological human tissues fixed in neutral buffered formalin and methacarnoy and embedded in glycol-methacrylate. The results show the compatibility of the AgNOR technique with this embedding medium as well as the possibility to obtain an adequate visualization of the specific silver precipitates (AgNORs) on a unique focal plane without appreciable nuclear overlap, making thus the valuation of the AgNORs less subjective.

Digestive System↗
PubMed2001

A novel method for correlating internal and external structure of individual myelinated nerve fibres.

A new method is described that enables longitudinal and cross sections of an individual nerve fibre to be cut at multiple specified sites along the fibre by the use of a unique marker system. In this way the internal structure of the fibre can be correlated with the external appearance. Individual myelinated nerve fibres are teased apart in epoxy resin and mounted onto a carbon-coated slide, and after orientation and marking of specific sites of interest are snap frozen to liberate the orientated and marked fibres for embedding on the surface of an epoxy resin block for subsequent longitudinal or transverse sectioning. This method is particularly useful for the correlative study of the myelin-axon relationships.

Axons↗
PubMed1995

The effects of culture environment on the response of human gingival fibroblasts to cyclosporin A.

In contrast to monolayer cell culture, the use of a 3-dimensional culture system creates an environment which is more physiologically comparable to conditions in vivo. This study aimed to investigate the effects of culture environment on growth and protein biosynthesis by 6 human gingival fibroblast cell lines exposed to cyclosporin A (CsA). Fibroblasts were grown both in monolayer culture on plastic and embedded within collagen gel. Cyclosporin A was added to cultures at a range of concentrations between 10(-5) and 10(-9) g/ml. Under both culture conditions CsA had little effect on cell growth at low concentrations but at the highest concentration of 10(-5) g/ml, there was a significant inhibitory effect on growth (P < 0.05). Protein production was not significantly affected by CsA in either culture system. Total collagen production appeared to be inhibited at high concentrations of CsA when cells were grown on plastic but remained unaffected when the cells were grown in collagen gel. Total protein and collagen production per cell in collagen gel was substantially greater compared with cells grown on plastic. We conclude that under the conditions of this investigation CsA did not directly stimulate growth or matrix-synthesis by normal human gingival fibroblasts cultured in 3-dimensional collagen gel or as monolayers on plastic.

Adult↗
PubMed2005

Staining of the Reinke crystalloids in the human testis--re-evaluation study.

Reinke crystalloid (CR)s are rod or corn shaped structures present in the interstitial cells (Leydig cell) of human testis. Due to existing controversies and because of their importance in histological studies, we decided to reevaluate their staining behavior with various dyes. Earlier it has been shown that hematoxylin and eosin dyes do not stain CRs even though their protein nature remains undisputed. In the present study, sections of testicular tissues embedded in glycol-methacrylate (GMA) showed that hematoxylin binds to CRs non-specifically and eosin stains them specifically. The reasons for stainability and/or non stainability of CRs with hematoxylin, eosin and other dyes are discussed.

Aged↗
PubMed1994

Antibody penetration into LR-White sections.

The purpose of this investigation is to study the ability of antibodies to penetrate sections of LR-WHITE resin. The methods used in this study were the following: (1) Reembedding of sections labeled with immunogold (1 nm) and peroxidase/DAB/gold chloride, (2) tilting of ultrathin sections treated with immunogold (1 nm), (3) immunolabeling of cylindrical structures embedded in LR-WHITE, (4) application of primary and secondary antibodies on opposite sides of ultrathin sections. Fibrin and human pituitary tissue was embedded in LR-WHITE and treated with anti-fibrinogen or anti-ACTH respectively (ACTH = Adrenocorticotropic hormone). No indication of antibody penetration into the section were found with either of the methods, contrary to findings in earlier publications. The significance of this result is that antigens cannot be demonstrated in the interior of LR-WHITE sections with post-embedding techniques. Furthermore, LR-WHITE resin may be used for quantitative immunoelectron microscopy, and the resin may be used for double immunogold labeling since the application of immunoreagents on opposite sides of the sections is completely safe.

Acrylic Resins↗
PubMed2002

Autometallographic localization of heavy metals in resin sections, cryosections and isolated cells of the mussel Mytilus galloprovincialis (L.).

In the present study, autometallography (AMG) has been performed on resin-embedded tissue sections, cryosections, as well as on isolated cells from the digestive gland, the gills and the haemolymph of mussels (Mytilus galloprovincialis) collected from the field. The AMG reaction was more intense in cryosections and isolated cells compared to resin sections. This intense AMG reaction found in cryosections and in isolated cells and the time effectiveness of the procedures enhances their use in a variety of studies, such as biomonitoring, even if small amount of metals are to be detected. In addition, the preparation of isolated cells does not require specific instruments or qualified personnel and, thus, the use of isolated cells is encouraging for AMG applications, although further laboratory investigation is required. On the other hand, the use of resin-embedded tissue sections for AMG applications, even though it is complicated and time consuming, leads to a high preservation of structural morphology and allows the exact localization of metals in discrete cellular compartments.

Animals↗
PubMed1996

Embedding undecalcified bone in polymethyl methacrylate: an improved method.

A number of improvements are described for the preparation of resin sections of undecalcified bone embedded in polymethyl methacrylate. Based on a modified resin mix, the modifications, which include a specially designed block clamp, have resulted in a simplified and quicker procedure with improved section quality. The method has been used routinely for investigating approximately 10,000 cases of metabolic bone disease for diagnostic purposes.

Bone Diseases, Metabolic↗
PubMed2001

A simple method for orienting silk and other flexible fibres in transmission electron microscopy specimens.

When microstructures are characterized by transmission electron microscopy (TEM), the interpretation of results is facilitated if the material can be sectioned in defined orientations. In the case of fibres, it is especially useful if transverse and longitudinal sections can be obtained reliably. Here we describe a procedure for orienting spider silk and other flexible fibres for TEM investigation. Prior to embedding in epoxy resin, the silk is wound around a notched support made from polyester film. No glue is required. After the silk and its supporting film have been embedded and the resin has been cured the film can be peeled away to reveal nearly perfectly orientated silk threads. Both transverse and longitudinal sections can then be cut with a microtome. The method can be extended to obtain sections at any intermediate orientation.

Animals↗
PubMed1993

Plastination: a new approach to morphological research and instruction with excised larynges.

Impregnation of biologic materials with curable polymer (plastination) allows wider use of human tissue for both basic and clinical research and instruction. The aim of this study was to determine for the first time the potential of this method in the field of laryngology. A feasibility study on 54 pig larynges established a detailed methodology for larynx plastination and determined the extent of shrinkage by using computer-assisted morphometry. The process involves dehydration, saturation with an appropriate intermediate solvent, and infiltration with cured polymer in vacuo. In the main study 20 fresh, intact human larynges and 12 laryngectomy specimens were submitted to plastination. The resulting resin blocks were cut with a diamond band saw into 0.8-mm sections in the transaxial plane. The resulting specimens are dry, odorless, and durable, and do not deteriorate with time. The subtle features of soft tissue pathology are well preserved. Shrinkage of plastinated larynges is less than 10%. The complete process is accomplished within 5 weeks. Staining of sections with toluidine blue provides an enhanced contrast between different types of tissue, allowing a clear identification of tumor invasion. Plastination is considerably faster than celloidin embedding and causes minor anatomic changes. It provides durable specimens of high quality for teaching purposes. In research, it allows the investigation of all tissue components in their undisturbed context in the borderline area between gross anatomy and histology.

Anatomy↗
PubMed1996

Bone metaplasia of urothelial mucosa: an unusual biological phenomenon causing kidney stones.

A kidney stone was analyzed by infrared spectrometry, by petrography using ground slices, and by undecalcified histology. Infrared spectrometry showed that the stone was composed of calcium oxalate monohydrate (whewellite), calcium oxalate dihydrate (weddellite), and calcium phosphocarbonate (apatite). Optical microscopy of the ground sections revealed tissue fragments within the stone containing small spaces resembling empty osteocyte lacunae. Histological analysis of methacrylate-embedded sections confirmed the presence of an area of heterotopic ossification. Urothelial mucosa is potentially capable of inducing bone formation and in this case the bony tissue had apparently functioned as a nucleation site for the calculus.

Adult↗
PubMed1997

Cyclosporin A-induced alterations of dentinogenesis in rat molars.

Cyclosporin A (CsA), a widely used immunosuppressive drug, induces gingival overgrowth and modifications of bone remodelling. The scope of this study was to investigate the possible effect of CsA on dentin. Thirty mg/kg/day of CsA were administered orally to male Sprague-Dawley rats for nineteen weeks. The same number of control rats received oil-based vehicle solution. Rats were anesthetized, and tissues were fixed by an intracardiac perfusion of fixative solution. Mandibles were dissected, demineralized, and processed for Epon embedding. Semi-thin sections of the first molars revealed alterations at the secondary dentin-pulp interface in four out of six experimental animals. The changes consisted of the formation of: 1) osteodentin spurs, in which the volume and interface with the secondary dentin varied from about 25,000 to 75,000 microns 3 and from 1400 to 3530 microns 2, respectively; 2) abnormally shaped and irregularly spaced incremental lines; and 3) numerous globular formations embedded in dentin or free in the pulp. These results indicate that CsA induces abnormal mineralized matrix formation in dentin and in the peripheral part of the pulp in rat molars.

Administration, Oral↗
PubMed1992

A modified Da Fano silver stain for demonstration of neurons and dendrites in glycol methacrylate-embedded brain tissue.

Golgi impregnation techniques are commonly used for characterization of neurons and their dendritic and axonal processes. Most of the widely used techniques require processing of fresh brain tissues, which limits the amount of material available for study. Additionally, the stained blocks must be subsequently embedded in paraffin, which produces considerable cellular shrinkage and distortion artifacts. Modification by one investigator of an early silver impregnation technique, designed to demonstrate the Golgi apparatus, allowed demonstration of neurons and their dendritic processes. Our further modification of the later technique, along with embedding of the stained tissue in glycol methacrylate, permits detailed examination of neurons and their processes in formaldehyde-fixed neonatal human brains. In cerebellar sections, this modified technique impregnates nearly all Purkinje cells, elucidating the fine structural detail of the developing neuronal dendritic tree and spines.

Brain↗
PubMed1992

Lectin-binding sites in quick-frozen, freeze-substituted extracellular matrix of rabbit corneal stroma: a comparative electron microscopic study with different embedding procedures.

The efficiency of Epon, Lowicryl K4M and LR White resins for electron microscopy was tested on the reactivity of carbohydrate residues to lectins in quick-frozen, freeze-substituted extracellular matrix of rabbit corneal stroma, without the use of any chemical fixation. Three lectins conjugated to gold particles were used in a post-embedding method: Wheat germ agglutinin, Concanavalin A and Ricinus communis agglutinin 1. Best gold-labelling was obtained with Lowicryl K4M for Wheat germ agglutinin, and with both Lowicryl K4M and Epon for Concanavalin A and Ricinus communis agglutinin 1. Tissues embedded in LR White gave less intense labelling for the three lectins used in comparison with the two other resins. This study demonstrates the crucial role of resins in the optimal preservation of biological activity of carbohydrate residues in cryotechnically-processed cornea for electron microscopy.

Animals↗
PubMed1997

Preparation of thin sections for Fourier Transform-Infrared microscopy: a new embedding medium for cellulosic samples.

Fourier Transform-Infrared [FT-IR] microscopy is a combination of instrumentation from which information can be derived about the structure and composition of materials; however, it presents unique problems for sample preparation. Traditional methods of preparing fiber cross sections employ embedding media such as methacrylates, epoxides and polyvinyl alcohols, all of which have groups in common with the cellulose molecule, and absorb in the same regions of the IR spectrum. Therefore, a new embedding method employing polystyrene has been developed for the preparation of cross and longitudinal sections of cellulosic fibers. Although polystyrene is a strong IR absorbing material, it can be completely removed from specimens prior to analysis. In addition, FT-IR spectra of cross sections have better resolution than conventional preparation methods employing ground samples prepared in a KBr disk.

Cellulose↗
PubMed1997

Whole joint embedding in polymethylmethacrylate: a method for preparing intact musculoskeletal organ systems for histomorphology and 3-D reconstruction.

Large and medium size undecalcified joints were embedded in methylmethacrylate resin. Sections of 600 microns prepared from polymethylmethacrylate blocks show minimal distortion and are suitable for surface staining and three-dimensional reconstruction. The 5 microns sections prepared from these slabs retain good cytological detail. This method permits the examination of musculoskeletal organ systems at both macroscopic and microscopic levels.

Animals↗
PubMed2002

Embedding in Spurr's resin is a good choice for immunolabelling after freeze drying as shown with chemically unfixed dendritic cells.

Immunocytochemical reactions on biological specimens depend on many factors, the most crucial one being the maintenance of antigenicity. Antigens are vulnerable at each stage during preparation for electron microscopy. One of the least traumatic methods of preparing biological tissues for post-embedding immunolabelling includes the following steps: (1) physical stabilization of the native biological material by rapid freezing (cryofixation) and keeping the immobilized biological sample at low temperature, thereby avoiding any movements of water, ions and macromolecules; (2) dehydrating the frozen biological material by freeze-drying at low temperature; (3) embedding of the dehydrated specimen. Here we show that embedding of chemically unfixed dendritic cells in Spurr's resin after cryofixation and freeze-drying enables the conservation of fine ultrastructure without cell distortion or shrinkage. Furthermore, we demonstrate the feasibility of protein localization in ultrathin sections by immunolabelling of the major histocompatibility class II molecules.

Cells, Cultured↗