Scanning electron microscopy in early human bladder neoplasia

Biopsies of healthy looking urothelium from 61 patients with transitional cell carcinoma (TCC) of bladder were examined by scanning electron microscopy (SEM) and light microscopy. A proportion (40 %) showed abnormal features on SEM, in particular pleomorphic microvilli (PMV) in at least one area. SEM appearances were graded into four categories depending upon divergence from normal. Patients were followed up at cystoscopy and one year later a strong correlation was noted between original abnormal SEM appearances and subsequent tumour recurrence. These early results suggest that SEM could be helpful in the diagnosis, assessment, and clinical management of the unstable urothelium.     

Scanning electron microscopy of the apical structure of human teeth

The objective of this research was to evaluate, by scanning electron microscopy, the apical structure of extracted human permanent teeth with different degrees of pulp and periapical pathology. A total of 25 teeth were extracted: 5 teeth with vital pulp (group I); 10 teeth with pulp necrosis without radiographically visible periapical lesion (group II); 10 teeth with pulp necrosis with radiographically visible periapical lesion (group III). The root apex was sectioned and processed for scanning electron microscopy. In groups I and II, fibers covered the root cementum and there was no cementum resorption or microorganisms. There were areas of cementum resorption in group III with microorganisms on the root apex surface (biofilm) and no fibers. The authors conclude that the presence of chronic periapical lesions causes severe changes in the apical structure with a destruction of fibers and different degrees of cementum resorption forming lacunae in which bacterial biofilm persisted.     

Scanning electron microscopy of synaptonemal complexes

The novel application of scanning electron microscopy to study whole-mount surface-spread synaptonemal complex complements of rye (Secale cereale) and rat (Rattus norvegicus) is described. Scanning electron microscopy is able to resolve the third dimension in such preparations and improve the tracing of the continuity of lateral elements without losing information that could be obtained by conventional transmission electron microscopy. This improvement is likely to benefit detailed studies of chromosome synapsis and karyology, and may provide a means of circumventing technical obstacles inhibiting the use of surface-spreads as substrates forin situ hybridization under the electron microscope.     

Scanning electron microscopy

The technology of scanning electron microscopy (SEM) is described in brief. Its application to the study of cell and tissue structure is demonstrated and the evolution of the concept of 'topographical histology' is discussed. Some current literature on the applications of SEM is reviewed under the headings of experimental pathology and human pathology. While SEM has become an indispensable technique for the experimental morphologist, its application to diagnostic pathology and cytology is still at an early exploratory stage.     

Electron microscopy of endothelial cells in culture: II. Scanning electron microscopy and OTOTO impregnation method

Summary A method is described whereby endothelial cells are treated with several cycles of osmium and thiocarbohydrazide then critical point dried. Cells grown on Formvar-coated gold grids can be examined directly by transmission electron microscopy, cells grown on glass strips are mounted on stubs for scanning electron microscopy and are scanned without further coating with gold or palladium.     

Low-temperature and conventional scanning electron microscopy of human urothelial neoplasms

The appearance of neoplastic human urothelium viewed by low-temperature scanning electron microscopy (LTSEM) and conventional scanning electron microscopy (CSEM) was compared. Fixed, dehydrated neoplastic cells viewed by CSEM had well-defined, often raised cell junctions; no intercellular gaps; and varying degrees of pleomorphic surface microvilli. The frozen hydrated material viewed by LTSEM, however, was quite different. The cells had a flat or dimpled surface, but no microvilli. There were labyrinthine lateral processes which interdigitated with those of adjacent cells and outlined large intercellular gaps. The process of fixation and dehydration will inevitably distort cell contours and on theoretical grounds, the images of frozen hydrated material should more closely resemble the in vivo appearance.     

Scanning electron microscopy analysis of the human zona pellucida: influence of maturity and fertilization on morphology and sperm binding pattern

Human oocytes from the same as well as from different patients have an extremely heterogeneous morphology of the zona pellucida surface as shown by scanning electron microscopy. For years it has been believed that this heterogeneous morphology plays an important part in the sperm-oocyte interaction. It was the aim of this investigation to analyse the morphology and the sperm binding patterns of the human zona pellucida. Oocytes were divided into four categories: mature, immature, fertilized and unfertilized. Four different types of zona morphology were detectable. They ranged from a porous, net-like structure to a nearly smooth and compact surface. No correlation could be established between zona type and oocyte maturity or zona type and achieved fertilization. However, fertilized (polyploid) oocytes had a more compact and smooth zona surface than unfertilized ones. The analysis of the number and distribution patterns of bound spermatozoa on the zona pellucida revealed extremely variable patterns regardless of the zona morphology. Significant differences between mature and immature oocytes did not appear. In both groups there were oocytes with either no or numerous bound spermatozoa on the zona pellucida. Oocytes overloaded with spermatozoa could only be found in the mature group. Unfertilized oocytes had fewer bound spermatozoa on average than polyploid zygotes.     

Application of low-vacuum scanning electron microscopy for renal biopsy specimens

Low-vacuum scanning electron microscopy (LV-SEM) has been developed which enables the observation of soft, moist, and electrically insulating materials without any pretreatment unlike conventional scanning electron microscopy, in which samples must be solid, dry and usually electrically conductive. The purpose of this study was to assess the usefulness of LV-SEM for renal biopsy specimens. We analyzed 20 renal biopsy samples obtained for diagnostic purposes. The sections were stained with periodic acid methenamine silver to enhance the contrast, and subsequently examined by LV-SEM. LV-SEM showed a precise and fine structure of the glomerulus in both formalin fixed paraffin and glutaraldehyde-osmium tetroxide-fixed epoxy resin sections up to 10,000-fold magnification. The spike formation on the basement membrane was clearly observed in the membranous nephropathy samples. Similarly to transmission electron microscopy, electron dense deposits were observed in the epoxy resin sections of the IgA nephropathy and membranous nephropathy samples. LV-SEM could accurately show various glomerular lesions at high magnification after a simple and rapid processing of the samples. We consider that this is a novel and useful diagnostic tool for renal pathologies.     

Simultaneous processing of substrate-dependent monolayer cultures for scanning and transmission electron microscopy

Summary A reliable method is described for processing substrate-dependent cells raised on culture-grade plastic for both scanning (SEM) and transmission electron microscopy (TEM). This technique allows collection of specimens for TEM and SEM from the same culture dish or flask. In this way it is possible to study the surface morphology (SEM) and thin section ultrastructure of cells from contiguous regions of a culture. Specific regions of a culture can be selected and processed so that specimens retain orientation throughout mounting or embedment and sectioning. The method is applicable both to confluent cultures as well as isolated colonies.     

Scanning electron microscopy of esophageal microvasculature in human infants and rabbits

Summary The microvasculature of the esophagus was studied by scanning electron microscopy of vascular corrosion casts in human infants and rabbits. In both species, segmental circumferential arteries arise from main longitudinal arteries, the latter giving off numerous perforating arteries. The tunica muscularis is supplied by branches of circumferential and perforating arteries, the submucosa and its glands by branches of perforatings. Terminal arborizations of perforating arteries feed a subepithelial capillary network. These capillaries are drained by a venous plexus in the lamina propria which is connected to a submucosal venous plexus. Perforating veins, running parallel to the corresponding arteries, connect the submucosal plexus with circumferential veins, and finally empty into main longitudinal veins. Valves were not present in any of the veins. Submucosal veins were less numerous in man than in rabbit. The number and caliber of equivalent vessels in human submucosal plexus decreased from the pharyngoesophageal to the gastroesophageal junction, suggesting the latter to be at particular risk in portal hypertension. The subepithelial capillary network reveals a longitudinal arrangement in rabbits, while the same network shows no preferential organization in human infants. The microvascular architecture of the esophagus in humans and rabbits is comparable, especially in the lay-out of the venous plexuses and the absence of venous valves. Therefore the rabbit could serve as an experimental model for studies on portal hypertension. The present results strongly suggest particular significance of the venous plexus in the lamina propria for the genesis of esophageal varices.     

Morphological characterization of different human cervical mucus types using light and scanning electron microscopy

BACKGROUND: This study was conducted on human cervical mucus using light microscopy (LM) and scanning electron microscopy (SEM). The objective was the morphological characterization of the different mucus types, with samples taken from the lumen of the cervix and from the different secretory zones of the cervical mucosa. METHODS: A total of 230 samples from 195 women were spread out on slides and air dried. The phenomenon of 'ferning' was observed and assessed in these samples using both LM and SEM. Further samples from the lumen of the cervix and the different secretory crypts were spread out on cover slips and fixed with glutaraldehyde (2.5%) to be studied by SEM. RESULTS: The results show the presence of four different morphological mucus types, namely L, S, P and G, in both types of sample using dried and fixed techniques. CONCLUSIONS: Mucus from the lumen of the cervix appears to be a morphologically heterogeneous entity. It contains different types of secretions, the proportions of which vary throughout the menstrual cycle. The different mucosal types show different types of crystallization, different patterns of ultrastructure (probably related to the arrangement of the glycoprotein network) and are produced in different secretory zones of the crypts in the cervix.     

Scanning electron microscopy in oral cytology

Sixty-three cell smears from oral mucosa were studied by scanning electron microscopy. Among them, smears from ten healthy controls showed three kinds of cells: flat (superficial) cells with linear anastomosing microridges and microvilli; polygonal (intermediate) cells with well-defined crests between their faces and numerous microvilli; and round (parabasal) cells entirely covered by microvilli. Twenty-five smears from patients with untreated squamous-cell carcinoma showed enlarged polymorphous cells (round, globular, and elongated); microvilli, variable in their dimensions, were irregularly distributed on their surfaces. Eighteen smears from patients with severe epithelial dysplasia showed polymorphous cells with discontinuous but obvious edges separating their faces and with irregular microvilli and ridges. Nine smears were also performed in patients with various other mucosal lesions (lichen planus, leukoplakia, white sponge naevus, pemphigus vulgaris, and herpes). All of these smears were studied comparatively between examination of smears and biopsies by light microscopy. The smears were truly reliable, particularly for distinguishing between dysplastic and tumoral cells.     

A comparative study of the surfaces of normal oral epithelia and inflammatory hyperplasias by scanning electron microscopy

The oral epithelia may show epithelial changes induced by the inflammation of the underlying lamina propria. Light microscopically, the epithelial changes are similar to epithelial dysplasia seen in a premalignant lesion. A scanning electron microscope permits a resolution higher than that of a light microscope. Therefore, it may elucidate the changes observed light microscopically. The purpose of this study was to examine the surface changes of the epithelia of parulides (gum boils) compared with those of normal oral epithelia to see if there were any surface changes due to the underlying inflammatory processes. A total of 3 specimens (1 buccal mucosa, 1 gingiva, and 1 hard palate) taken from 3 patients, one specimen from each patient, were used as controls. A total of 2 parulides from 2 patients, 1 specimen from each patient, were used as experimentals. Each specimen was cut in two. One half was prepared for light microscopy and the other half was prepared for scanning electron microscopy. Light microscopically, it was confirmed that the buccal mucosa was nonkeratinized, the gingiva was parakeratinized, and the hard palate was orthokeratinized. The epithelium of the parulis was nonkeratinized to parakeratinized with increased intercellular spaces and distinct epithelial changes similar to epithelial dysplasia. By scanning electron microscopy, the nonkeratinized mucosa (buccal mucosa) showed that most of the ridges ran parallel to each other and the parakeratinized mucosa (gingiva) and the orthokeratinized mucosa (hard palate) exhibited ridges surrounding uniform pits. The surface of the parulis of the first patient showed relatively smooth areas with residual pits, reminiscent of that of keratinized mucosa, and the surface of the parulis of the second patient showed relatively smooth areas with residual parallel ridges, reminiscent of that of nonkeratinized mucosa. Light microscopically, the oral epithelia overlying the intensely inflamed lamina propria showed distinct epithelial changes similar to epithelial dysplasia seen in a precancerous lesion but appeared normal except for markedly decreased numbers of microridges by scanning electron microscopy.     

Comparative studies of the same adenocarcinoma cells,macrophages, and mesothelial cells by light microscopy,scanning electron microscopy,and transmission electron microscopy

The identification of cells in body cavities of cancer patients is sometimes difficult to make. In order to make a definite cytological diagnosis, we observed the same cells by using light microscopy (LM)-scanning electron microscopy (SEM)-transmission electron microscopy (TEM). In this study we first stained cells by the Papanicolaou method after fixation in 1% glutaraldehyde for LM, and then attempted to observe them successively by SEM-TEM after fixation in 1% paraformaldehyde and 1.25% O^s0⁴. Our method and procedures in examining successively one and the same cells in body cavity fluids by using LM, SEM, and TEM ensured accurate discrimination among adenocarcinoma cells, mesothelial cells, and macrophages. The results of this study suggest that LM-SEM-TEM may be of diagnostic value in distinguishing among mesothelial cells, macrophages, and adenocarcinoma cells. This method also succeeded in disclosing differences between the ultrastructure of the cell surfaces, and those of the cytoplasm, and of the nuclei It is desirable that LM-SEM-TEM observation can be introduced into various aspects in order to obtain an improvement in the diagnosis by cytologic examination, the judgment of therapeutical effects, drug selection, and prognostic presumption. Diagn Cytopathol 1994; 11:333–342. © 1994 Wiley-Liss, Inc.