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PubMed2005

Fine needle aspiration cytology diagnosis of gastrointestinal stromal tumors utilizing scanning electron microscopy.

BACKGROUND: Digestive stromal neoplasms are the most frequent undifferentiated mesenchymal tumors. The outcome of these malignancies is difficult to predict and the histogenesis is still controversial. However, the frequent and specific expression of CD117 (c-kit) by these tumors could imply an origin from interstitial cells of Cajal. Our objective was to analyze the role of fine needle aspiration cytology, cell block preparation, and immunocytochemistry in the interpretation of gastrointestinal stromal tumors, and to establish scanning electron microscopy as a useful research aid for pathologic changes of the surface cells of gastrointestinal stromal tumors, not totally appreciated by light microscopy. MATERIAL AND METHODS: Twelve cases of gastrointestinal stromal tumors were included in this study, in which fine needle aspiration cytology was performed. RESULTS: On aspirated material, the tumor cells formed closely packed cohesive tissue fragments with high cellular density often in bloody background, or fascicles with parallel side-by-side arrangements of the nuclei. On cell block biopsy material, gastrointestinal stromal tumors were highly cellular spindle or epithelioid tumors with basophilic appearance. Immunocytochemically, they were CD117 positive in all twelve cases, CD34 positive in nine, weakly smooth muscle actin-positive in five, and S-100 and GFAP-negative in all cases. The scanning electron microscopy study showed a strong correlation with the cytomorphological profile. CONCLUSIONS: Gastrointestinal stromal tumors show a broad morphologic variety, but nuclear pleomorphism by cytology alone, rarely correlates with malignant potential. In the appropriate clinical and radiological setting, a confident diagnosis of gastrointestinal stromal tumors can be documented by fine needle aspiration cytology, cell block, immunocytochemical, and scanning electron microscopy results.

Biopsy, Needle↗

PubMedDate not supplied

Scanning electron microscopy of normal human peripheral blood cells.

To investigate the surface morphology of peripheral blood cells, venous blood specimens drawn from 16 normal healthy subjects were studied with scanning electron microscopy. Blood cells were fixed with 2% glutaraldehyde and stained with Riu's A and B solutions. Red blood cells, platelets and specific types of leucocytes were identified and photographed through a light microscope. The cells were then fixed with OSO4, dehydrated, dried and metal-coated. Observation with a scanning electron microscope revealed that the erythrocytes were biconcave in shape with smooth surfaces. Adhesion to one another was in rouleaux formation. The surface morphology of the neutrophils was characterized by irregular and branching ridges. Prominent pits on the cell membranes were also noted. A few microvilli, similar to those seen in lymphocytes, were distributed sporadically on the surface. Lymphocytes were much smaller in size than neutrophils. Variable amounts of short upright microvilli, which probably represented the different functional status of the cells, were observed. The monocytes possessed folding cellular processes, while the eosinophils had a villous and granular appearance. Circulating platelets existed in two forms: the native form with discoid shape and the activated form with pseudopodia. The surface was smooth. It is concluded that most peripheral blood cells can be identified by their specific topographic characters. The information thus obtained by scanning electron microscopy can facilitate the cytodiagnosis of abnormal specimens such as sputum, pleural effusion and ascites.

Blood Cells↗

PubMed1990

High resolution scanning electron microscopy of stereocilia in the cochlea of normal, postmortem, and drug-treated guinea pigs.

The morphology of hair bundles has been studied by high resolution scanning electron microscopy using a variety of fixatives, including glutaraldehyde, glutaraldehyde-picrate, glutaraldehyde-tannic acid, glutaraldehyde followed by post-fixation in osmium tetroxide, and the osmium thiocarbohydrazide technique. Critical evaluation of several metal coatings, gold, gold-palladium, and platinum has been carried out. Both the surface texture of stereocilia and their cross-links are sensitive to fixation and metal coating. We are of the opinion that glutaraldehyde gives the best general quality of fixation and preservation for all types of cross-links. We have described three major sets of cross-links: first, lateral links connecting stereocilia within the same row; second, lateral links connecting stereocilia of adjacent rows; and third, upward-pointing links, one per stereocilium, connecting the tip of each shorter stereocilium to the lateral surface of the adjacent taller stereocilium. Current physiological and anatomical evidence suggests that the lateral links couple the individual stereocilia within the hair bundle so that they function as a single mechanical unit. The upward-pointing tip links are ideally placed to respond to mechanical deformation of the hair bundle, being stretched when the stereocilia are deflected in the excitatory direction towards the tallest row and relaxed when deflected in the opposite, inhibitory direction. Postmortem morphological changes are detected within 15 minutes of cardiac arrest and become progressively more pronounced in time. These results enabled us to distinguish specific drug-induced changes which could not be attributed simply to cell death. Effects of cisplatin and kanamycin upon hair bundles are described. The work reported here is based on studies using the guinea pig cochlea. Some of the postmortem changes described have also been confirmed in human cochleas. It is stressed that many of the postmortem and drug-induced effects can only reliably be studied by high resolution scanning electron microscopy coupled with appropriate preparation procedures.

Animals↗

PubMed1987

Uncombable hair (pili trianguli et canaliculi): evidence for dominant inheritance with complete penetrance based on scanning electron microscopy.

Uncombable or spun-glass hair (pili trianguli et canaliculi) is an uncommon condition in which the hair is "unmanageable" and has a distinct appearance on scanning electron microscopy. The hair is usually grossly abnormal in infancy and childhood, but may become normal later in life. Although dominant inheritance has been observed, most cases have been sporadic. Both recessive and dominant transmission with incomplete penetrance have been suggested as modes of inheritance. We report the occurrence of this condition in a young girl, her brother, and her father. Although the proposita and her brother had characteristically uncombable hair, their father appeared normal and denied any history of hair abnormality. However, the characteristic hair morphology was observed on scanning electron microscopy in all 3 relatives, documenting dominant transmission and complete penetrance of the gene in this family.

Child, Preschool↗

PubMed1987

In vitro excystation of Giardia from humans: a scanning electron microscopy study.

The in vitro excystation of Giardia lamblia on cysts isolated from human feces was studied. After purification by sucrose gradient, cysts were incubated in a pepsin-acid solution, then placed in a modified HSP3 medium where excystation occurred within a few minutes. The excystation procedure was studied by continuous observations by light microscopy and sequential observations by scanning electron microscopy (SEM). The in vitro excystation was stopped at timed intervals during incubation by addition of a large amount of 1% glutaraldehyde. The excystation process began by the cyst wall opening at one pole. Flagella protruded rapidly, the parasite emerged progressively from the cyst envelope, posterior end first, the empty cyst collapsed and shrank. Although flagella emerging from the organism were distinguishable, the cell body had not yet shown all the morphological features of the G. lamblia trophozoite. A radical rearrangement of the organism occurred gradually: initially oval in shape, the parasite became round, then elongated, flattened, and underwent cytokinesis. The daughter trophozoites acquired their typical morphological features: the shape, the adhesive disc with the C-shaped structure distinctly visible on the ventral surface, and the definite placement of the flagella. These observations obtained on G. lamblia by SEM were comparable to those obtained with G. muris.

Giardia↗

PubMed1998

Scanning electron microscopy of central nervous system cerebrospinal-fluid-contacting surfaces: a bibliography (1963-1995).

This bibliography is compiled to assist in locating papers related to the application of scanning electron microscopy (SEM) to cerebrospinal-fluid-contacting surfaces in vertebrates. The use of SEM by neuroscientists has continued apace since the publication of the first bibliography in 1980. SEM studies now include more than 50 species of vertebrates and range from cyclostomes to humans; they encompass development from embryo to senescence and concern both normal and pathologic morphology. Although remarkable strides have been made toward a greater understanding of many aspects of the structure and function of cerebrospinal-fluid-contacting surfaces, many significant problems await the judicious application of scanning electron microscopy.

Animals↗

PubMedDate not supplied

[Effects of progesterone and nomegestrol acetate on the endometrial epithelium of the rabbit. A study with scanning electron microscopy].

Immature female rabbits were tested by the Clauberg-MacPhail technique using progesterone (P), or nomegestrol acetate (NOM), a 19-norprogesterone derivative. The endometrial surface was observed by scanning electron microscopy. Estrogen priming followed by treatment with P induced changes on the endometrial surface which were very close to those observed in menopausal women under sequential estroprogestative therapy. After treatment with NOM the aspect of endometrium surface was very close to those observed after treatment with P. This is in accordance with the pharmacological profile of the product. Scanning electron microscopy confirms the previsional value of Clauberg-MacPhail's test and provides useful complementary information for the pharmacological understanding of a new synthetic progestogen.

Animals↗

PubMed2003

Biofilm formation on intraocular lenses by a clinical strain encoding the ica locus: a scanning electron microscopy study.

PURPOSE: To determine whether the Staphylococcus epidermidis strain carries the intercellular adhesion (ica) locus, which encodes production of adhesins mediating adherence to biomaterials and to study, with scanning electron microscopy, the morphologic features of this coagulase-negative Staphylococcus strain that adheres to intraocular lenses (IOLs). METHODS: Polymerase chain reaction amplification was used to investigate whether the isolate under study (S. epidermidis clinical strain N890074) carries the ica locus. Sterile intraocular lenses (IOLs) were incubated in bacterial suspension either for 5 minutes or 1 hour. IOLs were then examined by scanning electron microscopy. RESULTS: Polymerase chain reaction amplification revealed that S. epidermidis N890074 contained the ica locus. The bacteria appeared to be anchored to the surface of the lenses by several different means-particularly by leglike appendages and a slime layer-which probably came into play step by step. CONCLUSIONS: For the first time in ophthalmology, to the authors' knowledge, photographs showing leglike appendages involved in the first phase of adhesion have been obtained. They also clearly visualize the slime layer containing the embedded bacteria. This study provides information about the nature and the genesis of these attachment processes. Adherence is known to be greater when the bacterial DNA contain the ica locus. Full knowledge of the pathogenesis of bacterial adhesion is necessary to gain a better understanding of IOL infection and endophthalmitis.

Adhesins, Bacterial↗

PubMed1992

Scanning electron microscopy of the small intestine during gluten-challenge in celiac disease.

The celiac disease syndrome is characterized by structural and ultrastructural alterations of the small intestine mucosa. According to criteria by European Society of Paediatric Gastroenterology and Nutrition, the conclusive diagnosis of celiac disease in children depends on the demonstration of histological relapse of the mucosa after reintroduction of gluten in the diet, as this syndrome is a permanent condition of gluten intolerance. Under these diseased conditions, the structure of the intestinal villi has been studied by light microscopy; morphological alterations were revealed only when the gluten challenge induced a clinical relapse. Scanning electron microscopy analyses of the intestinal mucosa in celiac diseased patients showed a strikingly uniform destruction of the villi with changes in their dimensions and arrangement. At high magnification the enterocytes were irregular in size and shape with a decrease and disruption of the glycocalyx. Reductions in length and density of microvilli were also clearly identified. Although these scanning electron microscopy findings could not demonstrate a relationship between the degrees of mucosal atrophy and the duration of the gluten challenge, they nevertheless revealed early stages of fine villous alterations that cannot be detected by the presently employed low resolution light microscopic techniques.

Autopsy↗

PubMed2000

In vitro MR imaging of hyaline cartilage: correlation with scanning electron microscopy.

OBJECTIVE: Our goal was to determine how the three-dimensional structure of hyaline cartilage affects its MR appearance and to correlate this appearance with detailed structural analysis using scanning electron microscopy and freeze-fracture sectioning techniques. MATERIALS AND METHODS: In vitro 7-T spin-echo MR images of hyaline cartilage specimens from four patients undergoing above-knee amputations were obtained parallel and perpendicular to the main magnetic field. Specimens were imaged with low- and high-power scanning electron microscopy after freeze fracturing. The corresponding images from both techniques were analyzed with specific attention to the three-dimensional structure of the cartilage, collagen fibril orientation, and respective changes in the MR appearance. RESULTS: Freeze fracturing of cartilage reveals a curved fracture plane. Expected changes in signal intensity predicted by the magic angle effect correlated with observed changes in signal intensity across the thickness of the sample. Changes in individual collagen fibril orientation did not correspond to MR layering. CONCLUSION: The three-dimensional organization of collagen in cartilage has a strong influence on the MR appearance of cartilage. This influence is caused by the restriction of water mobility and the resulting magic angle effect caused by curvature of the collagen network, possibly because of the influence on proteoglycan orientation.

Adult↗

PubMed1986

[Scanning electron microscopy and light microscopy studies on the retina of chick embryos in cell culture].

Histological and scanning electron microscopy studies (SEM) suggest a classification of neural elements into five main types: receptor cells, bipolar cells, horizontal, amacrine, and ganglion cells in dissociated cell cultures of the retina from 7 to 10 days old chick embryos. By use of SEM the development of the receptor cell inner segments was observed. At the same time many protrusions were noticed at the receptor cell surface. Specific synaptic contacts between the axons of the receptor cells and the dendrites of the bipolar neurons, as well as unspecific contacts between the pericarya of the receptor cells and other dendrites were demonstrated. The bipolar neurons showed smooth cell surfaces, however, the horizontal cells appeared rough on the cell surfaces. Müller cells were always found adjacent to the photoreceptor cells.

Animals↗

PubMed1985

Scanning electron microscopy as an analytical tool for the study of calcified intrauterine contraceptive devices.

Within the endometrial cavity intrauterine contraceptive devices (IUDs) become encrusted with cellular, acellular, and fibrillar substances. Scanning electron microscopy was used to study the crust. Cellular material consisted mainly of blood cells and various types of bacteria. The fibrillar material appeared to be fibrin which was omnipresent in the crust and formed a thin layer immediately over the IUD surface. X-ray microanalysis of the acellular component of the crust revealed the presence of calcium. No other major peaks were identified. Near the IUD surface characteristic calcium phosphate crystals were present. Their microanalysis showed peaks for calcium and phosphorus. X-ray diffraction of the crust however, showed it to contain only calcite. It is through the use of scanning electron microscopy that calcium phosphate has been detected in the IUD crust and a fibrillar layer has been visualized on the IUD surface. This study further demonstrates the effectiveness of SEM analytical techniques in the area of biomedical research.

Adult↗

PubMed1987

[Scanning electron microscopy studies of the structure of tissue in the cochlear opening of the cochlear aqueduct].

The structure of the internal and external tissue of the cochlear opening of the cochlear aquaeduct was examined by light microscopy on semithin sections and by scanning electron microscopy. The whole area is filled with a net of mesenchymal cells. The cell axes are randomly orientated inside the aquaeduct. On the outside of the cochlear aquaeduct fibrocytic tissue fills a space which is triangular in cross-section between the basal part of the cochlea wall of the tympanic scala and the middle portion of the round window membrane. In this area the direction of the net is uniform and it gives the impression of anchorage of the round window membrane on the perilymphatic side. The rim bordering the perilymphatic space is a dense net but not fully closed. The scanning electron microscopic pictures taken perpendicular to this border structure show clearly a texture of mesenchymal cells with open spaces. No closed "membrana limitans" was found. The possible function of the fixation of the round window membrane to the perilymphatic space giving rise to an asymmetric perilymph movement is discussed with regard to the physiology of sound transmission.

Animals↗

PubMed1999

Evaluation of initial attachment of human gingival fibroblast cells to biodegradable membranes in vitro by light and scanning electron microscopy.

Guided tissue regeneration procedures using resorbable membranes have become accepted therapy for treating periodontal defects. Resorbable collagen and synthetic polylactide and polyglycolide copolymer membranes have been found to support regeneration and preclude the need for surgical removal. This study was undertaken to assess and compare the initial attachment of human gingival fibroblast cells to four collagen-based membranes (fascia lata, fascia temporalis, dura mater, and Type I bovine collagen) and a synthetic polylactic acid-based membrane (resolut). Human gingival fibroblasts were grown from explants of normal tissue obtained during surgical reduction of retromolar tissues. Membrane specimens were placed in separate culture wells and incubated with fibroblasts for one hour. The number of adherent cells was evaluated by light microscopy using an ocular grid system and detailed examination was performed by scanning electron microscopy. The results of evaluation by light microscopy indicated that initial cell attachment was significantly less in the polylactic acid-based membrane group than in the collagen-based membrane groups (P < 0.01). However, no significant differences were found among the collagen membrane groups in terms of fibroblast attachment (P > 0.01). Scanning electron microscopy examination of fibroblasts cultured directly on barrier membranes indicated that the collagen-based membranes appeared to facilitate cell attachment, whereas the polylactic acid-based membrane exhibited a morphology that was not conducive to attachment of human gingival fibroblasts. Based on these limited in vitro results, it appears that collagen-based membranes offer greater potential than polylactic acid-based membranes for guided tissue regeneration at surgical sites.

Absorbable Implants↗

PubMed2000

Comparison of results of scanning electron microscopy and magnetic resonance imaging before and after administration of a radiographic contrast agent in the tendon of the deep digital flexor muscle obtained from horse cadavers.

OBJECTIVE: To analyze the tendon of the deep digital flexor (TDDF) muscle of the forelimb in horses by use of a contrast radiographic agent (gadopentate dimeglumine [Gd-DTPA/Dimeg]) and magnetic resonance imaging (MRI) and to determine the concentration of water protons in the tendons by use of MRI. SAMPLE POPULATION: 8 TDDF harvested from the forelimbs of 6 horse cadavers. PROCEDURE: Examinations were performed on the same portion of each tendon. Tendons were examined by use of two techniques: MRI before and after treatment with Gd-DTPA/Dimeg as well as scanning electron microscopy. RESULTS: Tendons did not have detectable signal intensity on MRI before treatment with Gd-DTPA/Dimeg; however, intravascular injection of Gd-DTPA/Dimeg allowed evaluation of the internal structure of the tendons Scanning electron microscopy images correlated well with images obtained by use of MRI before and after administration of Gd-DTPA/Dimeg. Localized spectra revealed the concentration of water protons in the TDDF. CONCLUSIONS AND CLINICAL RELEVANCE: The techniques used in this study provided information about internal organization of the TDDF in horses. Analysis of results revealed that the best technique involved vascular injection of contrast medium. Results of MRI correlated well with results for scanning electron microscopy. After administration of Gd-DTPA/Dimeg, MRI provided additional information about tendon morphologic characteristics. This technique may be of value for examination of tendons in lame horses.

Animals↗

PubMed2002

Use of light and scanning electron microscopy to examine colonisation of barley rhizosphere by the nematophagous fungus Verticillium chlamydosporium.

Barley roots were readily colonised by the nematophagous fungus Verticillium chlamydosporium. Light microscopy (LM) but also low temperature scanning electron microscopy (LTSEM) revealed details of the colonisation process. Hyphae were found on the rhizoplane often with dictyochlamydospores. Hyphae of V. chlamydosporium penetrated epidermal cells, often by means of appressoria. A hyphal network was formed in epidermal and cortical cells. Likewise, hyphal coils were found within root cells next to transverse cell walls. Cortical cells were the limits of fungal colonisation, since no hyphae were seen in the vascular cylinder. Modifications of root cell contents (phenolic droplets and callose appositions) were common three weeks after inoculation with V. chlamydosporium. These features may indicate induction of plant defence reactions in late stages of root colonisation by the fungus. Both LTSEM and LM have proved extremely useful to describe root colonisation by the fungus. The results found may have implications in the mode action of nematophagous fungi against plant parasitic nematodes.

Animals↗

PubMed2005

A vision-based, 3D reconstruction technique for scanning electron microscopy: direct comparison with atomic force microscopy.

High-resolution, detailed 3D reconstructions of biological specimens obtained from scanning electron microscopy stereo-micrographs and proprietary software were compared with Tapping-Mode AFM datasets of the same fields. The reconstruction software implements several original solutions including a neural adaptive point-matching technique, the ability to build an irregular triangulated mesh rather than a regular orthogonal grid, and the ability to re-map one of the original images exactly onto the reconstructed surface. The technique was applied to human nerve tissue to obtain 1,424 x 968-pixel, texture-mapped datasets, which were subsequently compared against 512 x 512-pixel AFM datasets from the same viewfields. Accounting for the inherent differences of the two techniques, direct comparison revealed an excellent visual match. The correspondence was also quantified by calculating the cross-correlation coefficient between corresponding altimetric profiles in SEM and AFM data, which consistently exceeded a figure of 0.9, with a rate of point mismatch in the order of 0.01%. Research is still underway to improve the robustness of the technique when applied to arbitrary images

Humans↗

PubMed2002

Structural aspects of the extracellular matrix of the tendon: an atomic force and scanning electron microscopy study.

The mutual interactions of small proteoglycans with collagen fibrils in the extracellular matrix remain to be completely understood. The present research investigated the extracellular matrix of the rat tail tendon by atomic force microscopy (AFM) as well as by scanning electron microscopy (SEM). Observations showed simply dehydrated specimens made of large heterogeneous fibrils, tightly packed in mutual contact with no visible interfibrillar spaces. Proteoglycans usually extended onto neighboring fibrils, forming an intricate interfibrillar weaving highly sensitive to chondroitinase digestion. Pre-treatment with cupromeronic blue only affected the proteoglycans side chains, which appeared better preserved but somewhat thickened. Observation of hydrated specimens by AFM confirmed the close packing of collagen fibrils and the abundance of collagen-bound proteoglycans. Interfibrillar bridges were only occasionally observed in this tissue, whose fibrils are instead tightly bound together by proteoglycans in a structure quite consistent with its functional requirements. The molecular machinery responsible for these interactions is the subject of ongoing research.

Animals↗