Plastic versus paraffin embedding for histopathology and immunocytochemistry.
Explore the source record for details and available documents.
Histological Techniques↗
SEARCH · Search PubMed
Results for “Plastic Embedding”
Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
A numerical procedure for choosing effective, low toxicity plasticizers for glycol methacrylate embedding.
A numerical method for selecting low toxicity plasticizers for glycol methacrylate (GMA) embedding mixtures is described. It involves use of various numerical parameters, namely; molecular weight, melting point, solubility parameter, and toxicity data. On the basis of these parameters, nine plasticizers were selected. Their effects on microtomy and tissue processing, and also their influence on tissue morphology and staining, were investigated. For tissue processed at low temperatures into GMA, using ethanol dehydration, the following compounds were as satisfactory as 2-butoxyethanol whilst being less toxic: 2-isopropoxyethanol, 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, 2-(n-butoxyethoxy)ethanol. However for tissues processed using the plasticizer as dehydrating agent, the optimum plasticizers were 2-isopropoxyethanol, 2-(2-methoxyethoxy)ethanol and 2-(2-ethoxyethoxy)ethanol. It is possible to give a numerical specification of the preferred plasticizers, and for the first procedure this is: a solubility parameter in the range 21-26 J0.5 cm-1.5 or higher, a melting point well below 0 degree C, and a rat oral LD50 greater than 12.52 mmol kg-1. It was also possible to analyse the differential effects of the dehydrating agents on histochemical and enzyme histochemical staining on a numerical basis, using a structure-activity relations approach.
Animals↗
Eosinophils and neutrophils in biopsies from the middle ear of atopic children with otitis media with effusion.
OBJECTIVE AND DESIGN: The majority of patients with otitis media with effusion (OME) and atopy have been shown to have elevated levels of eosinophil cationic protein (ECP) in their middle ear fluid. The mechanism underlying these elevated levels of ECP is not clear. The purpose of this study was to investigate the feasibility of a quantitative determination of eosinophils and neutrophils in the middle ear lining by specific immunocytochemical markers, in order to study the extent of the involvement of these cells in patients with OME. METHODS: Bilateral middle ear biopsies from five children with persistent OME and atopy confirmed by in vitro testing were evaluated for the presence of eosinophils and neutrophils with monoclonal antibodies against specific granule proteins. Five subjects who had no signs of effusion or infection but were undergoing routine tympanoplasty for dry perforations served as controls. The biopsies were embedded in a plastic resin to improve the structural preservation of the target cells and to increase the resolution in the light microscope. Dual markers were used to determine which marker was better for eosinophils and neutrophils, respectively. The following markers were used: eosinophil cationic protein (EG2), and eosinophil peroxidase (EPO) for eosinophils and myeloperoxidase (MPO) and human neutrophil lipocalin (HNL) for neutrophils. RESULTS: Antibodies against EPO gave a more localized and intense staining than antibodies against EG2. Antibodies against HNL appear more specific to neutrophils than antibodies against MPO that also recognize monocytes. The number of cells was determined both in the tissue and in the mucus covering the epithelium. Eosinophils and neutrophils were present in the subepithelial connective tissue and in the mucus blanket in the middle ear of patients with OME in significantly higher number than in the control group. In general, there were more inflammatory cells in the mucus than in the tissue itself, but the number of inflammatory cells in the mucus showed a significant positive correlation with the number of inflammatory cells in the tissue. There was a significant positive correlation between the number of neutrophils and the number of eosinophils in the tissue as well as in the mucus, irrespective of which marker was used. CONCLUSION: The results of this study show the feasibility of using specific antibodies to identify eosinophils and neutrophils in the middle ear. The initial data suggest that atopic children with OME have higher numbers of such cells as compared to non-OME controls.
Adolescent↗
Application of laser scanning confocal microscopy in the analysis of particle-induced pulmonary fibrosis.
Laser scanning confocal microscopy (LSCM) allows us to simultaneously quantitate the degree of lung fibrosis and distinguish various pathological lesions of intact lung tissue. Lucifer Yellow has been shown an ideal fluorescent stain to examine the connective tissue matrix components of embedded lung tissue with LSCM. We evaluated the use of LSCM in quantitating lung fibrosis and compared this procedure with the more traditional method of assessing fibrosis by measuring hydroxyproline, a biochemical assay of collagen. CD/VAF rats were intratracheally dosed with silica (highly fibrogenic), Fe2O3 (non-fibrogenic), and saline (vehicle control) at a high dose of 10-mg/100 g body weight. At 60 days post-instillation, the left lung was dissolved in 6 M HCl and assayed for hydroxyproline. Silica induced increases of 58% and 94% in hydroxyproline content over the Fe2O3 and control groups, respectively. The right lung lobes were fixed, sectioned into blocks, dehydrated, stained with Lucifer Yellow (0.1 mg/ml), and embedded in Spurr plastic. Using LSCM and ImageSpace software, the tissue areas of ten random scans from ten blocks of tissue for each of the three groups were measured, and three-dimensional reconstructions of random areas of lung were generated. The silica group showed increases of 57% and 60% in the lung areas stained by Lucifer Yellow over the Fe2O3 and control groups, respectively. Regression analysis of hydroxyproline vs. lung tissue area demonstrated a significant positive correlation (p < 0.05) with a correlation coefficient of 0.91. Histological analysis of right lung tissue revealed a marked degree of granulomatous interstitial pneumonitis for the silica group, which was absent in the Fe2O3 and control groups. No significant differences (p < 0.05) in hydroxyproline content and measured tissue area were observed between the Fe2O3 and control groups. LSCM, and its associated advanced image analysis and three-dimensional capabilities, is an alternative method to both quickly quantitate and examine fibrotic lung disease without physical disruption of the tissue specimen.
Animals↗
Comparing apical preparations of root canals shaped by nickel-titanium rotary instruments and nickel-titanium hand instruments.
This study measured displacement of canal centers in extracted human teeth after preparation by Lightspeed and nickel-titanium K-files. The specimens were divided into two groups (n = 11), after radiographing the roots from the buccolingual and mesiodistal planes with pathfinding files in situ. More strongly and less strongly curved canals were, respectively, assigned to the Lightspeed and nickel-titanium K-file groups. Using a reassembly technique, cross-sections at 1.25 mm, 3.25 mm, and 5.25 mm from the apices were made of the experimental roots embedded in clear plastic. Stereomicroscopic 35-mm slides were taken of the uninstrumented sectioned canals. The sections were reassembled and then prepared to size 50 Master Apical Rotary and size 40 Master Apical Files, for the Lightspeed and K-file groups, respectively. Similar 35-mm slides of the instrumented canals were taken and electronically superimposed over their uninstrumented counterparts. Displacements of root canal centers after preparation and increases in cross-sectional areas of the prepared root canals were evaluated at specific levels. No significant differences in displacement of canal centers or between the mean cross-sectional areas of the instrumented root canals were recorded between the Lightspeed and K-file groups. Both types of instruments produced similar displacement of canal centers after preparation.
Anatomy, Cross-Sectional↗
[Simplified method of embedding sections in plastics].
Explore the source record for details and available documents.
Histological Techniques↗
Embedding of skeletal tissue in plastic for vascular and histological study to demonstrate delayed endochondral ossification in Leghorn type fowl.
A method is described which enables visualisation of the blood supply in developing avian long bones, followed by the preparation of undecalcified histological sections from the same material. The circulatory system was perfused with a solution of fixative, dye and barium sulphate. The skeletal tissue was cleared in plastic resin before embedding and tissue blocks were cut into 1 mm slabs. The vascular canals were then examined with a dissecting microscope. Slabs were re-embedded in resin and 5 microns sections cut for routine undecalcified histological staining. Focal areas of delayed endochondral ossification were demonstrated in slabs prepared from the proximal ends of femora of White Leghorns. These lesions are considered a less severe form of the dyschondroplastic condition occurring in broilers.
Animals↗
Mixing embedding media in plastic bags.
Explore the source record for details and available documents.
Histological Techniques↗
Wrinkle-free thick sections of tissue embedded in hard plastics.
Explore the source record for details and available documents.
Fixatives↗
Separation of epoxy-embedded cell cultures from plastic flasks for electron microscopy.
Monolayers of cells grown in ordinary plastic flasks are fixed and embedded "in situ" into Epon. When polymerized at 40 C for 4 days instead of the usual 60 C, the Epon sheet containing the cells is easily detached from the bottom of the plastic container. The Epon sheet is observed by light microscopy as a histological preparation. Ultrathin sectioning of preselected areas can then be carried out in a horizontal plane.
Animals↗
Embedding plant tissue with plastic using high pressure: a new method for light and electron microscopy.
An embedding technique has been developed to overcome difficulties that confront light and electron microscopists working with so-called "hard-to-embed" plant tissue. The method was originally described for freeze-dried material. It uses a modified Quickfit Rotaflo Valve and low heat to generate high pressure to aid in the infiltration and embedding of tissue with propylene oxide and plastic. The technique is not too cumbersome and requires 6 days from the dehydration step to the end of the polymerization process. Thick sections (1-2 micrometer) obtained from material prepared by this method stain readily with toluidine blue, and thin sections for the electron microscope stain satisfactorily following standard treatment with uranyl acetate and lead citrate. The thin sections are stable under the beam of the electron microscope. Results indicate that the quality of tissue preservation with this high pressure embedding technique is as good as tht observed using standard embedding methods for electron microscopy.
Histological Techniques↗
The role of collagen II and cartilage fibril-associated molecules in skeletal development.
OBJECTIVE: The extracellular matrix (ECM) of hyaline cartilage contains an elaborated collagen fibrillar network, which is essential for the mechanical stability and the proper function of the tissue. Cartilage collagen fibrils consist of collagen II, the quantitatively minor collagens IX and XI, and several non-collagenous fibril-associated proteins. To understand the role some of these molecules in skeletal development, we have generated transgenic mouse strains harboring ablated genes for collagens II and IX, and matrilin-1. DESIGN: Mice lacking collagen II, collagen IX and matrilin-1 have been established earlier in our laboratory using standard techniques. To determine the consequences of the null mutations we used skeletal staining, histochemical and immunohistochemical assays, in situ hybridization and ultrastructural analysis. RESULTS: Transgenic mice deficient in collagen II (Col2a1-/-) die at birth and display a severely malformed skeleton characterized by abnormal endochondral ossification and impaired intervertebral disc development. Mice lacking collagen IX (Col9a1-/-) are viable and develop an osteoarthritis-like phenotype in knee joints between 9-12 months of age. To test the possibility that the reduction in collagen II content has an influence on the onset of degenerative changes of articular cartilage, we have generated mice, which are heterozygous for the collagen II null mutation and homozygous for the collagen IX null mutation. Col2a1+/- Col9a1-/- mice show no accelerated development of osteoarthritis compared with the collagen IX knockout animals. Finally, mice lacking matrilin-1, a non-collagenous glycoprotein that binds to both collagen fibrils and aggrecan, develop normally without detectable abnormalities in their skeleton. CONCLUSIONS: Our transgenic mouse strains carrying null mutations in genes encoding cartilage ECM proteins demonstrate that these proteins have different roles during skeletal development. Collagen II is important for cartilage formation, collagen IX for cartilage maintenance and matrilin-1 is redundant.
Animals↗
Embedding brain specimens in transparent plastic.
A simple, reliable and practical technic for permanently embedding brain specimens in plastic is discussed. The anatomic details, including the natural colors, are so well preserved that they give a real picture of the morphologic details, such as preservation of anatomic landmarks and pathologic alterations. The specimen can be observed from different angles, enhancing the student's opportunity for visual examination. Clearing of the specimen with visualization of the vascular tree after injection with opaque dyes may be accomplished. The procedure is recommended for museums and laboratory teaching.
Anatomy↗
Morphology of GABAergic neurons in the inferior colliculus of the cat.
The goal of the present study was to provide a comprehensive and quantitative description of neurons immunoreactive for gamma-aminobutyric acid (GABA) in the inferior colliculus (IC) of the cat. Neurons were investigated with two different antisera and two different incubation methods. Free-floating frozen or vibratome-cut sections were incubated either with an antiserum to glutamic acid decarboxylase (GAD) or to GABA conjugated to protein with glutaraldehyde. Additional 1.5-microns-thick sections were incubated with the GABA antiserum after embedding and removal of the plastic. Quantitative data were obtained from much of this material. Despite the use of these different antisera and reaction methods, the results obtained were remarkably similar. The results show that GAD- or GABA-positive neurons represent a significant population of cells in the central nucleus of the IC, up to 20% of the neurons. Most of these neurons have large or medium-sized perikarya. In contrast, immunonegative neurons are medium-sized or small. Many GABA-positive neurons had proximal dendrites or somata oriented in parallel to the fibrodendritic laminae of the central nucleus and are presumed to be disc-shaped neurons. Other have an orthogonal orientation and are presumed to be stellate cells. Large GABA-positive neurons form two groups, those with many axosomatic endings and those with few. Collectively, these observations suggest that there are several types of GABAergic neuron in the central nucleus and, by extension, that these may participate in many types of inhibitory circuits.
Animals↗
Bone density measurements of the paranasal sinuses on plastinated whole-organ sections: anatomic data to prevent complications in endoscopic sinus surgery.
OBJECTIVE/HYPOTHESIS: Although anatomic data regarding the gross anatomy of the paranasal sinuses are available, severe complications of endonasal sinus surgery (ESS) are frequently reported. To understand and to avoid these complications, density of bony walls of the paranasal sinuses were studied in this report. Special attention was given to the analysis of the bone density in regions where minor and major complications occur in ESS. METHODS: Thirty cadaver heads were embedded in epoxy resin. The plastic blocks were sectioned with a diamond-coated wire saw into 1.0-mm thick, parallel slices in axial, coronal, and sagittal planes for 10 specimens each. The slices were x-rayed and scanned with a computerized image analyzing system. For each specimen the bone density in 12 regions of interest was measured. RESULTS: Besides the macroscopic examination of the plastinated specimens, a bone density analysis based on x-ray films is presented. Lowest bone density was found at the lateral wall of the sphenoid sinus (3.31 +/- 0.99 mm aluminum [Al]); highest density was measured at the roof of the sphenoid sinus (12.91 +/- 1.75 mm Al). Overall bone density in female specimens was 0.41 mm Al (mean) lower than in male specimens. CONCLUSIONS: This study is the first to use plastinated whole-organ serial sections and bone density images for the analysis of potential complications in ESS. The illustration of regions with minor and major bone density of the paranasal sinuses and the ethmoid floor as presented in this study may help the novice sinus surgeon to minimize the risks of ESS and to avoid severe complications.
Absorptiometry, Photon↗
A new method for the embedding of small animals and organs in plastic.
A new method for embedding of small animal organs in plastic is described. After the material has been fixed in solutions preserving its colour, and dehydrated gradually using an aqueous solution of glycerol and potassium acetate it is embedded in methylmetacrylate. The method is described in detail and involves moulding at minus 5 degrees C.
Plastics↗
A simple embedding technique for monolayer neuronal cultures grown in plastic flasks.
An in situ embedding technique for monolayer cultures for subsequent ultrastructural studies is described. Dehydration is carried out in graded ethanol series without propylene oxide, and Epon is used as a final embedding medium. The advantage of this method is that the plastic flask with the embedded material can be stripped off easily without affecting the monolayer culture and that the plastic does not dissolve in Epon.
Animals↗
Pneumocystis carinii pneumonia in the acquired immunodeficiency syndrome: diagnosis using minilavage samples.
Over a 30-month period, we evaluated 74 patients with acquired immunodeficiency syndrome (AIDS) for suspected opportunistic pulmonary infection. All had abnormal findings on chest roentgenogram. Sixty patients (81%) were found to have Pneumocystis carinii pneumonia (PCP). We assessed the yield of various diagnostic methods, and found that bronchoalveolar lavage samples obtained by the instillation of 20 to 50 ml of normal saline (minilavage) contained detectable organisms in 51 of 53 patients (sensitivity of 96%) when the samples were embedded in plastic, cut in thick sections (1 micron), stained with toluidine blue O, and evaluated by light microscopy. In comparison, the diagnostic yield was 94% for lung biopsy, 85% for touch preparation of lung tissue, 32% for bronchial washing, and 14% for brush biopsy. It is significant that minilavage samples embedded in plastic were positive in all seven patients who did not have transbronchial lung biopsy because they were at high risk for complications. We conclude that the process of embedding minilavage samples in plastic and evaluating thick sections stained with toluidine blue O is a sensitive method of diagnosing PCP in patients with AIDS.
Acquired Immunodeficiency Syndrome↗