Search PubMed⌕ Search

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.

At least 1,387 records · Page 77Linked to original sources
PubMed1985

The effect of section thickness and embedding media on the observed S-phase labelling index of artificially selected cell populations from neonatal mouse liver and spleen.

Following an intraperitoneal injection of tritiated thymidine to neonatal mice, livers and spleens were removed and their labelling indices were derived autoradiographically. This was done in a number of ways: (1) from tissue imprints on gelatinised glass slides; (2) from tissue embedded in JB4 plastic sectioned at thicknesses of 2, 5 and 7 micron; and (3) from tissue embedded in paraffin wax and sectioned at 7 micron. The results show that the indices from the JB4 embedded sections increase as the section thickness decreases, and that this relationship persists down to the notional section thickness of zero in the tissue imprints (in which all the cells are in contact with the autoradiographic emulsion). Indices from the 7 micron paraffin wax embedded sections are surprisingly close to the values from the imprints, are higher than indices from the 5 and 7 micron JB4 embedded sections, and are not significantly different (at the 2% level) from those from 2 micron JB4 embedded sections. Possible reasons for these results are discussed in respect of the autoradiographic process and in relationship to various mathematical correction factors which have been proposed to take account of beta-particle self-absorption in thick sections. It is concluded that none of these correction factors is of value and that the embedding medium has an important effect on the observed labelling indices. Comparisons between labelling indices, therefore, should be made only when they are derived from similarly embedded material at the same section thickness.

Animals↗
PubMed1994

The human adenoid. A morphologic study.

OBJECTIVE: We examined the route by which antigen on the surface of the adenoid may be brought into contact with the lymphoid follicles in the submucosa of the adenoid. DESIGN: We studied under light and electron microscopy 13 adenoids from children undergoing elective surgery. Portions of all of the specimens were fixed in formalin and embedded in paraffin and plastic for hematoxylin-eosin and periodic acid-Schiff staining. Portions of four adenoids were fixed in glutaraldehyde for electron microscopy. RESULTS: Two major types of epithelium were evident by light microscopy: a ciliated or squamous epithelium containing few lymphocytes and a nonciliated-flat epithelium with a heavy infiltration of lymphocytes ("lymphoepithelium"). Scanning microscopy showed the surface of this lymphoepithelium to be composed largely of cells with multiple microfolds known as M-cells. Freeze-fracture technique showed many lymphocytes under the M-cells. Transmission electron microscopy showed the lymphocytes to be located in compartments formed by the epithelial cells. Light microscopy study of 50 serial sections embedded in plastic suggested that the compartments communicated to form intraepithelial channels for the lymphocytes. CONCLUSION: The epithelium of the adenoid has areas with ciliated epithelium adjacent to areas with epithelium containing M-cells and intraepithelial lymphatic channels. HYPOTHESIS: The lymphoepithelium of the adenoid is a mechanism for transporting antigen via the M-cells to the underlying lymphoid follicles.

Adenoids↗
PubMedDate not supplied

How a child builds its brain: some lessons from animal studies of neural plasticity.

Although the potential vulnerability of children's brain development is generally recognized, relatively little is known about the timing, resiliency, or mechanisms involved. While animal research should be applied only cautiously to human policy, some findings do have important clinical implications. This paper briefly reviews animal studies demonstrating the effects of experience on brain structure. Contemporary theories emphasize the self-organizing potential of brain structure, particularly regions that seem to have evolved for the purpose of storing information. We emphasize three major findings: (1) many regions of the brain are responsive to experience, but they differ in the types of information stored and in their developmental timing. (2) One type of plasticity is typically embedded in a developmental program, and it requires appropriate timing and quality of the information stored for the animal's development to be normal. (3) Another category of plasticity stores information that is idiosyncratic and unpredictable, but is often useful for species such as humans that learn throughout their life span. We therefore expect that some aspects of human brain development use the first type of plasticity and that abnormal experience or deprivation may cause lasting harm to brain and behavior. However, because the other type of plasticity lasts a lifetime, efforts such as psychotherapy or social interventions may help heal a wounded brain.

Animals↗
PubMed1994

Distribution of alveolar wall per unit volume in the human lung.

Firstly, to assess the reproducibility of a computerised image analysis method of measuring alveolar size in terms of the alveolar wall surface area per unit volume (AWUV) in normal non-smoking adult human lungs fixed in inflation, one lung was fixed by simple manual prebronchial perfusion with formaldehyde (wet-fix), another by prolonged perfusion with formaldehyde followed by air until semi-dried (semi-dry). Blocks from both lungs were taken to assess the relative value of plastic and paraffin wax embedding. There was no statistical difference in AWUV between plastic and paraffin sections from each lung, but the wet-fix method gave statistically significantly (P < 0.05) higher AWUV readings than the semi-dry method. Secondly, when a whole semi-dry lung slice was divided into 66 blocks, the AWUV distribution was not random but largest in the centre and smallest in the periphery anteriorly and superiorly. This is obviously important in sampling of lung tissue for morphometry and other purposes.

Adult↗
PubMed2003

Development of a fluorescence in situ hybridization method for cheese using a 16S rRNA probe.

A 16S rRNA fluorescence in situ hybridization (FISH) method for cheese was developed to allow detection in situ of microorganisms within the dairy matrix. An embedding procedure using a plastic resin was applied to Stilton cheese, providing intact embedded cheese sections withstanding the hybridization reaction. The use of a fluorescein-labelled 16S rRNA Domain Bacteria probe allowed observation of large colonies of microbial cells homogeneously distributed in the cheese matrix. FISH experiments performed on cheese suspensions provided images of the different microbial morphotypes occurring. The technique has great potential to study the spatial distribution of microbial populations in situ in foods, especially where the matrix is too fragile to allow manipulation of cryosections.

Cheese↗
PubMed2005

Paraffin-embedded manipulated blastocysts: a tool to demonstrate stem cell plasticity?

One of the big question marks in current stem cell research is whether there is true plasticity of adult progenitor cells (APC) or if cell fusion is the principle source of the supposed plasticity. The generation of chimeras by injecting adult progenitor cells into blastocysts is not new. This paper describes an efficient embedding technique for murine blastocysts injected with human APC. This method could help in establishing a novel tool to analyse the process of plasticity, if it truly exists. If this is the case, this technology could be of great help to characterize surface markers of stem cells in great detail. On the other hand, fusion of cells could also be investigated. A system of embedding blastocysts was set up using paraffin for further analysis by means of light microscopy and immunohistochemistry. The embedding of the chimaeras consists of fixing them first with paraformaldehyde in phosphate-buffered saline (PFA/PBS), embedding them in gelatine, fixing the gelatine block with PFA/PBS and finally fixing the gelatine block in a Petri dish by embedding it in paraffin. Using this protocol, the morphology of the blastocysts is well preserved.

Animals↗
PubMed1979

Preparation and observation by SEM of hemopoietic cells cloned in soft agar.

A method is described to prepare clones of hemopoietic cells grown in soft agar for scanning electron microscopy (SEM). A critical modification of the otherwise quite standard SEM processing procedure for biological samples involved the use of silver micropore disks as an adherent substrate to support the highly labile, deformable agar slabs. This support allows maintenance of the normal flat pancake shape of the specimen through the thiocarbohydrazide osmium ligand binding steps, dehydration, and critical point drying. With this support and careful dissection of the surface agar with a fine steel needle using a stereomicroscope, selected areas and depths within the colony can be exposed and examined by SEM. Surface topography of cloned cells can be correlated with intracellular cytological features by excising areas of interest and directly embedding them in plastic for thin-section preparation and viewing by transmission electron microscopy (TEM). The dried-specimen-teasing method appears useful, because of the ease of preparation of the specimens, its reproducibility, and the degree of visibility and preservation of cell surface structures and intraclonal relationships. Our initial observations, using combined EM techniques, indicate that clonal cell topography is highly variable and that this variability appears to be related both to the relative age and proliferative status of the colony. Based on work to date, we suggest that topographical and spatial analysis, in vitro of cloned, agar-embedded hemopoietic stem cells is possible with simple modifications of conventional SEM preparative techniques.

Agar↗
PubMed1983

Failure of one design of surface replacement knee arthroplasty due to loosening deformation and wear of the plastic femoral component.

Twenty four knee prosthesis femoral and tibial components of the 'load angle inlay' design, removed for loosening and pain were examined in the scanning electron microscope, light microscope, and volume loss measured using a simple gauge. In all cases the deformation of the plastic (femoral) component was seen both by increase in the curvature of the inner surface and wear usually on the edge of the bearing surface. Two pairs were subluxed prior to removal from the patient and these not only produced gross deformation of the plastic components, but maximum volume loss of the components examined; the knees exhibited gross instability. The tibial (metal) components stood up remarkably well in all cases, both in wear and deformation which was minimal but sinking and rotation of the plateau did occur for the most part on the external side. Scratch patterns seen on the tibial components were clearly seen and gave an indication of the direction and amount of sliding between the components; in some cases these scratch lines were in more than one direction probably indicative of loosening and instability. Short deep scratches were usually indicative of bone and/or cement particles embedded in the plastic components, abrasive wear was seen on 92 per cent of the femoral components, and cracks were seen on two-thirds, usually parallel and close to the sides.

Adult↗
PubMed1989

Fat intestinal absorption in the catfish--a histochemical study in glycol methacrylate embedded tissue.

The intestinal absorption of lipids was investigated in plastic sections from glycol methacrylate embedded intestine after fat administration. In the catfish, the lipids are absorbed by the enterocytes of the proximal intestinal segment, thus forming fat cytoplasmic inclusions that were demonstrated by Sudan black B staining. The histochemical characterization of lipids by the Nile blue sulphate test revealed the neutral or triglyceride nature of the cytoplasmic droplets, both after the corn oil and oleic acid feeding. There is lipid accumulation in the lamina propria and lymphatic vessels.

Animals↗
PubMed1985

Microtubule distribution in cultured cells and intact tissues: improved immunolabeling resolution through the use of reversible embedment cytochemistry.

To investigate the detailed distributions of microtubules in cultured cells and intact tissues we developed a reversible embedment method for antibody labeling of sectioned material. Fixed tissues were infiltrated with fully polymerized polymethylmethacrylate dissolved in an organic solvent. Evaporation of the solvent left the tissue embedded in hard plastic. After sectioning by conventional methods, the plastic was extracted and sections were processed for indirect immunofluorescence to label microtubules. Clear images of microtubules were observed in sections of cultured epithelial cells, intact chick intestinal epithelium, and dividing sea urchin eggs. Microtubules in the differentiated epithelium of the chick intestine generally paralleled the long axis of the cells and did not focus on a microtubule-organizing center. Mitotic cells of the intestinal epithelium appeared similar to the mitotic cells of epithelial lines in culture. In sections of dividing sea urchin eggs detailed images of spindle and astral fibers were revealed. Immunoelectron microscopic labeling for tubulin was performed on sections of Pt K1 cells using secondary antibodies adsorbed to 20-nm gold particles. Semi-thick sections viewed by high-voltage electron microscopy showed both the overall distribution of microtubules and their detailed interactions with other cellular organelles. Mitochondria were often aligned along labeled microtubules. Reversible embedment cytochemistry should provide a general method for high resolution labeling of cells and tissues with affinity probes.

Animals↗
PubMed1977

Procedure for the embedment and ultrastructural visualization of cells cultured on plastic microtest plates.

The polystyrene Microtest plate has served as an excellent means of quantitation in the interaction of immunological, chemotherapeutic and radiobiological treatments with cultured cells. In order to assess the accompanying ultrastructural changes it was necessary to develop a technique which allowed cells grown in the wells of the plates to be embedded for electron microscopy. Conventional epoxy resin embedding techniques require the use of propylene oxide as a clearing agent. Unfortunately propylene oxide is a solvent of the polystyrene plates. By the substitution of absolute ethanol for propylene oxide, toluidine blue staining during the procedure and other preparative techniques it was feasible to prepare reacted cells grown in Microtest plates for electron microscopy.

Cells, Cultured↗
PubMed1988

High-grade non-Hodgkin's lymphoma of B-cell type. I. Histopathology.

One hundred and twenty-eight cases of high-grade malignant B-cell lymphoma were studied with a plastic re-embedding technique and classified according to the Kiel classification. The cytological details could be better recognized than in the original paraffin sections, thus permitting a more precise definition of the various lymphoma types. The entities centroblastic and immunoblastic lymphoma are more precisely defined and supplemented by the addition of several new variants. In contrast to the present Kiel classification we separate Burkitt's from lymphoblastic lymphoma. In all cases investigated, the B-cell nature of the tumour cells was proven by immunohistochemistry using monoclonal antibodies. The four entities of high-grade malignant B-cell lymphoma described in this paper are: (1) centroblastic lymphoma with four morphological variants (monomorphic, polymorphic, multilobated and centrocytoid); (2) immunoblastic lymphoma with three morphological variants (with or without plasmacytic differentiation, with many lymphocytes); (3) Burkitt's lymphoma and the closely related Burkitt's lymphoma-like lymphoma with plasmablastic differentiation; and (4) lymphoblastic lymphoma. Only the centroblastic lymphomas (in 17%) showed occasional follicular growth pattern, which further confirms the view that they are derived from germinal centre cells.

B-Lymphocytes↗
PubMed1999

Quantitation of spinal cord demyelination, remyelination, atrophy, and axonal loss in a model of progressive neurologic injury.

Spinal cord pathology, such as demyelination and axonal loss, is a common feature in multiple models of central nervous system (CNS) injury and disease. Development of methods to quantify spinal cord pathology objectively would aid studies designed to establish mechanisms of damage, correlate pathology with neurologic function, and assess therapeutic interventions. In this study, we describe sensitive methods to objectively quantify spinal cord demyelination, remyelination, atrophy, and axonal loss following the initiation of a progressive inflammatory demyelinating disease with Theiler's murine encephalomyelitis virus (TMEV). Spinal cord demyelination, remyelination, and atrophy were quantified from representative 1-microm-thick cross sections embedded in Araldite plastic using interactive image analysis. In addition, this study demonstrates novel, automated methodology to quantify axonal loss from areas of normal-appearing white matter, as a measure of secondary axonal injury following demyelination. These morphologic methods, which are applicable to various models of CNS injury, provide an innovative way to assess the benefits of therapeutic agents, to determine mechanisms of spinal cord damage, or to establish a correlation with sensitive measures of neurologic function. J. Neurosci Res 58:492-504.

Animals↗
PubMed1982

The origin of lipid phagocytes in the central nervous system: I. The intrinsic microglia.

The potential for the transformation of the normal microglial cell to a lipid phagocyte was studied by light and electron microscopy in the brains of rodents and by light microscopy only in primates. All were subjected to some form of hypoxia-ischemia and the microglial response was examined in regions of selective neuronal destruction (SND) so that infarction was deliberately excluded. In vivo perfusion-fixation was employed in all animals and light microscopic examination was carried out on paraffin- and sometimes celloidin-embedded material. Semithin plastic sections from several regions of the rodent brains were used for light microscopy but ultrastructural studies were confined to the hippocampus. In all animals the microglia were activated and transformed into rod cells exhibiting phagocytic properties but only a minority gave rise to lipid phagocytes. Blood vessels were normal in all animals and no hematogenous elements were identifed in the the parenchyma. As neuronal ghosts could be identified for up to 3 weeks it was concluded that the capacity of the microglia for phagocytic activity was limited.

Animals↗
PubMed2006

Glucocorticoid induces micro-fat embolism in the rabbit: a scanning electron microscopic study.

The objective was to identify fat emboli in the arterioles of the femoral bone marrow by scanning electron microscopy (SEM) after glucocorticoid administration. Female adult rabbits weighing 3.5-4.0 kg received a single injection of prednisolone at a dose of 4 mg/kgBW. The day after injection was designated as day 1. Control rabbits were injected with only physiological saline and killed on day 14. The femoral bone marrow was obtained on days 5, 8, and 14, and processed for SEM. Aortic blood serum was passed through a filter, and the filter was processed for SEM. Some SEM specimens were embedded in a plastic resin and sectioned for correspondence of SEM-photomicroscopy (PM) or SEM-transmission electron microscopy (TEM). In the controls, small fat globules were present in sinusoids and venules but were absent from the arterioles. On day 5, fat globules were found in the lumina of both sinusoids and arterioles, possibly due to the effect of glucocorticoid. Complete arteriolar occlusion was not found. On day 8, fat globules were often encountered in the venous and arteriolar lumina. Some small arterioles were completely occluded by fat emboli. On day 14, fat globules were present in the arterioles, and some small and large arterioles were completely occluded. Blood drawn from the aorta contained fat globules in both the controls and rabbits injected with prednisolone. A small amount of prednisolone induced the presence of fat globules in arterioles as early as day 5, complete occlusion of small arterioles on day 8, and occlusion of large arterioles on day 14.

Adipocytes↗
PubMed1991

Double lectin and immunolabelling for transmission electron microscopy: pre- and post-embedding application using the biotin-streptavidin system and colloidal gold-silver staining.

Pre- and post-embedding methods are described that can be used for consecutive localization of two intracellular cytoplasmic binding sites in cells and tissues embedded in acrylic plastic for transmission electron microscopy. Both applications make use of the biotin-streptavidin system with colloidal gold detector particles and involve silver staining of the first gold signal to a predetermined size. Silver augmentation effectively masked any free binding sites on the biotinylated molecule and on the streptavidin complex of the first labelling reaction, thereby allowing a second cycle with the same detection system. Excellent ultrastructural localization was obtained with silver lactate as the silver ion donor in the developing solution, and the enhancement treatment did not destroy or even visibly reduce target site reactivity for the subsequently applied probe. Using these methods it was possible to achieve specific double lectin and immunological labelling; they could, however, be adapted to dual or multiple-labelling procedures with any biotinylated molecules.

Animals↗