Scanning electron microscopy最新文献

The phase changes calcium oxalate trihydrate-weddellite, weddellite-calcium oxalate monohydrate and calcium oxalate trihydrate-whewellite are individually examined at the atomic level from a theoretical point of view; concomitantly the topological requirements necessary for phase stability are clarified for each structure type. In solution a sequential series of phase transitions according to the steps calcium oxalate trihydrate-weddellite-whewellite is not likely to be energetically favoured; direct conversion of calcium oxalate trihydrate to whewellite should be, instead, ordinarily expected. It is formally demonstrated that along two axial directions a set of atoms is in essentially identical positions in both weddellite and whewellite. This notwithstanding, it is concluded that epitactic catalysis cannot and should not be considered a common mechanism for the formation of whewellite from weddellite (and vice versa) or of kidney stones in general.

The doctor of today must adopt the 'cellular way of thinking' in the evaluation of diseases. This ultrastructural outlook provides him with much indispensable information that also serves a practical purpose. A diseased cell organelle is at the basis of every clinical sign and any attempt of therapy must be aimed at that specific point of lesion. We intend, in the light of a long experience, to propose to clinicians a new way of thinking in which a precise correlation between symptoms and submicroscopic changes of the cell is considered. Many different examples amply justify this proposal. Electron microscopy can contribute by enabling identification of structural subcellular modifications suitable for the finest differential diagnosis, more and more complete understanding of pathogenic pathways of various diseases, the establishment of guidelines for precise pharmacological interventions at the molecular level.

Morphometrical and X-ray elemental information was extracted from Scanning Transmission Electron Microscopy (STEM) images of hepatic lysosomes of a patient with idiopathic hemosiderosis before and after treatment by phlebotomy. The elements of interest were iron, stored in pathological quantities in hepatic lysosomal structures and cerium, used as a capture ion after a cytochemical reaction to detect acid phosphatase activity in the lysosomal structures. Morphologically the lysosomal structures are heteromorph and the elements iron and cerium are heterogeneously distributed. With "reduced raster" (= reduced scanning area) analysis at 16 X 16 pixelpoints (integrating image and X-ray microanalysis), a marked difference in the area of the cross sectioned lysosomal structures before and after treatment could be demonstrated. Simultaneously the difference in the relative orientation of the elements iron and cerium before and after phlebotomy could be visualized. Chelex ion exchange beads, loaded with 11.5% w/w iron, and coembedded with the tissue blocks, were used as an internal standard. A mean iron peak to background ratio was obtained and a factor, converting ratio to absolute iron concentration, was calculated. The same calculation procedure, now per pixelpoint, was followed for the hepatic lysosomal structures. A marked difference in iron concentration in the individual lysosomal structures was observed before and after treatment by phlebotomy.

Cells from Xenopus laevis blastulae have a poorly developed ability to adhere to Sepharose beads covalently coupled to bovine plasma fibronectin (FN-beads). They do, however, have the ability to adhere to con A-beads and cytodex-1 and cytodex-3 beads. Beginning at the early gastrula stage, there is a progressively increasing ability of cells to adhere to FN-beads. Gastrula cells adhere to FN-beads by the formation of large ruffling lamellipodia. These cells can translocate on the surface of FN-beads; and when attached to both beads and the surrounding glass substratum of culture vessels, have the ability to move the beads extensively. Gastrula cells also have the ability to adhere to but not move upon con A-beads, wheat germ agglutinin-beads, and soy bean agglutinin-beads. They do not adhere significantly to Tetragonolobus purpureas agglutinin-beads. These results suggest that there are increasing numbers of fibronectin receptors present on the surface of embryonic amphibian cells during the period of gastrulation. They may explain the differential distribution of fibronectin-containing fibrils in vivo as observed by scanning electron microscopy.

This report documents phorbol ester (TPA)-induced changes in cell morphology, and in vitro growth patterns in 9 patients with hairy cell leukemia (HCL), 21 with B-type CLL and non-Hodgkin's lymphoma in leukemic phase (NHL), and 10 with acute non lymphoblastic leukemia (ANLL). TPA caused cells from HCL to adhere strongly and produce elongated cytoplasmic extensions. Many of these cells had an appearance resembling fibroblasts, while others showed marked surface ruffling and spreading containing increased dense bodies, and phagolysosomal vacuoles as seen by transmission electron microscopy. This HCL in vitro growth pattern after TPA exposure differed from that seen in B-CLL and NHL cells, which only adhered moderately after 72 hours and readily detached in clumps. CLL and NHL-cells did not show ultrastructural features of macrophages but had either plasmacytic or HCL features. It is suggested that these different growth patterns may aid in distinguishing HCL from other B-cell neoplasias. The expression of surface markers, tartrate resistant acid phosphatase (TRAP) and Ig secretion were studied in some B-CLL, NHL and HCL cells after exposure to different concentrations of TPA for up to 6 days. Results showed that the documented changes were frequently both dose and time dependent and the most striking HCL-features were encountered after 6 days incubation with higher concentrations of TPA. However, individual variation from case to case was noted. Nevertheless, it seems that TPA induces neoplastic B-cells to mature into secreting plasmacytoid lymphocytes, and cells with features of HCL with variable expression of surface markers and TRAP.

This paper summarizes our studies of IUD-related disease with those previously published by others. Our data are based upon 51 IUDs and 42 index cases of IUD-related disease demonstrating specific processes. Gross, dissecting microscope, scanning electron microscope and X-ray microanalysis examinations were made of selected IUDs and associated tissues. Tissue associated with the IUDs revealed inflammation in 59.4%, calcific material in 6.3% and no abnormality in 34.4%. IUD-associated tissue responses were accompanied by changes of the IUD; these changes involved deposition of substances upon the IUD surface and degradation of the IUD itself. Disintegration of the IUD, its string or both, has been repeatedly observed. The material deposited upon the surface of the IUD included proteins and calcium salts. The changes which involve the IUD and the host appear to be operative in the genesis of IUD-related disease. Inflammatory changes and infections are the most common IUD-related disease processes and are also the mechanisms commonly associated with the most serious complications of IUD use, reproductive failure and death. We propose that serious IUD-related disease is caused by or is a direct consequence of processes which alter the IUD and which potentiate inflammation and infection. A model amenable to testing is proposed.

Scanning electron microscopy (SEM) permits a three-dimensional study of the surface morphology of the organ of Corti that is very useful in evaluating the condition of the apical end of the hair cells and the stereocilia. However, some laboratories have experienced problems with curling of the basilar membrane during critical point drying of cochlear specimens prepared for SEM evaluation using the Murakami or osmium thiocarbohydrazide-procedures. This curling of the basilar membrane can obstruct the view of the reticular lamina and the ciliary ends of the hair cells. We have used a dissection method, referred to as the anchor technique, to overcome basilar membrane curling. This technique removes all the structures above the reticular lamina but leaves the basilar membrane attached to the spiral ligament and the lateral bone to which the spiral ligament is anchored. Individual cochlear turns are dissected in this manner and mounted on the same examination stub for SEM evaluation. Maintenance of the lateral attachment of the basilar membrane requires additional dissection time but eliminates the problem of curling during critical point drying. An additional benefit is that mounting the individual turns on the same examination stub facilitates evaluation and photomicroscopy of the surface morphology. The anchor technique has been used successfully on the guinea pig and should be appropriate for most mammalian cochleas.

This article reviews the applications of SEM methods to human bone pathologies referring to studies made at UCL. We consider the methods which may be most suitable; these prove to be not "routine" in the context of most bio-medical applications of SEM. Valuable information can be obtained from a bone sample if its edges are ground flat, before making either a matrix surface preparation by washing away all the cells or a mineralizing front preparation, by also dissolving the osteoid-for which hydrogen peroxide is recommended to produce a robust specimen. BSE contrast from a cut block surface can be used to measure bone phase volume. SE contrasts from natural surfaces (trabeculae, canals and lacunae) can be used to study forming, resting and resorbing surfaces both qualitatively and quantitatively (except in the case of histological osteomalacia, where the existence of osteoid will go undetected and reversal lines will be difficult to distinguish from recently resorbed surfaces). We also recommend the use of PMMA embedded bone blocks, which can be used as obtained from the pathologist, but are better embedded by a more rigorous procedure. BSE image analysis can be used to quantitate bone density fractions opening up a completely new investigative method for the future. Osteoid can be measured automatically using CL if the bone sample is block stained with brilliant sulphaflavine before embedding or if a scintillant is added to the embeddant. We give examples of observations made from a number of bone diseases: vitamin D resistant rickets, osteogenesis imperfecta; osteomalacia; osteoporosis; hyperparathyroidism; fluorosis; Paget's disease; tumour metastasis to bone.

The improvement in scanning electron microscopy (SEM) techniques has permitted us to describe the microstructure of the liver. By SEM, the liver peritoneal surface is composed of flat mesothelial cells possessing microvilli and cilia. Hepatic sinusoids connect the portal vessels with the terminal branches of the hepatic vein (central veins). Endothelial cells of the portal space arteries are elongated and arranged longitudinally, while those of the central and portal veins are polygonal and flattened, possessing microvilli. The sinusoidal endothelial cells show both small fenestrations (sieve plates), up to 200 nm in diameter, and large ones, up to 1 micron. Within the sinusoids are seen bridging structures, covered by fenestrated endothelium, seeming to have a fibrillar core. Kupffer cells resemble macrophages, showing microvilli, blebs, lamellipodia and filopodia. Within the Space of Disse are seen the fat-storing cells, having laminar dendritic projections. The polyhedral liver cell faces the Space of Disse (vascular pole) or faces an adjacent hepatocyte (biliary pole). Vascular facets are evenly covered by microvilli. Biliary facets show a central longitudinal depression, bordered by microvilli (bile hemicanaliculi). Canaliculoductular junction and bile duct epithelia show blebs, microvilli and cilia. Up to now, fetal liver and liver pathology have been scarcely investigated by SEM: in the future, they can be successfully approached by three-dimensional studies.

High magnification studies of the fenestrated capillary endothelium in the zona fasciculata (ZF) of rat adrenal glands were performed using the objective lens stage of an analytical scanning electron microscope (SEM) equipped with a lanthanum hexaboride emitter (LaB6). Resolution of surface substructure of the luminal membrane obtained with specimens decorated with gold/palladium (Au/Pd) was compared with that observed in others sputter coated with tantalum (Ta). High magnification (50,000x) of the fenestrated endothelium demonstrates that tantalum coating of the cryofractured adrenals improves the substructural detail compared to that seen in Au/Pd decorated specimens. The procedures used in specimen preparation, metal deposition and secondary electron imaging (SEI) are described. Quality imaging achieved using the objective lens stage is a result of the elimination of the SE-III component derived from backscattered electrons. Rat adrenals exhibited uniformly patent capillaries. High magnification micrographs of capillary walls were randomly recorded in two morphometric studies of the fenestral content of capillaries in the rat adrenal cortex. Adrenocorticotropic hormone (ACTH), when administered to rats following dexamethasone (DEX) treatment, significantly reduced the fenestrae/micron 2 of endothelial surface and increased the mean size of fenestrae. After hypophysectomy, the number of fenestrae/micron 2 declined over 48 h; within 2 h after ACTH was given to rats hypophysectomized 48 hours earlier, the fenestrae/micron 2 had increased two-fold. These studies indicate that ACTH plays an important role in modulating fenestral content of the capillary endothelium in the adrenal cortex.