Life Sciences Commons^™

Microscopic Analysis Of Dna And Dna-Protein Assembly By Transmission Electron Microscopy, Scanning Tunneling Microscopy And Scanning Force Microscopy, T. Müller-Reichhert, H. Gross

Scanning Microscopy

To investigate DNA and DNA-protein assembly, nucleic acids were adsorbed to freshly cleaved mica in the presence of magnesium ions. The efficiency of DNA adhesion and the distribution of the molecules on the mica surface were checked by transmission electron microscopy. In addition, various kinds of DNA-protein interactions including DNA wrapping and DNA super-coiling were analyzed using electron microscopy. In parallel, this Mg²⁺/mica method can be applied (1) to analyze embedded DNA by scanning tunneling microscopy, (2) to visualize freeze-dried, metal coated DNA-protein complexes by tunneling microscopy, and (3) to image DNA or DNA-protein interaction in air or …

The Appearance Of Endothelium In Small Arteries After Treatment With 5-Fluorouracil. An Electron Microscopic Study Of Late Effects In Rabbits, M. Cwikiel, J. Eskilsson, J. B. Wieslander, U. Stjernquist, M. Albertsson

Scanning Microscopy

Cardiotoxicity is an unexplained toxic manifestation of 5-fluorouracil (5-FU). Its possible mechanism could be a direct cytotoxic effect on the vascular endothelium. We have tested this hypothesis in an experimental study in rabbits, using scanning and transmission electron microscopic evaluation of endothelium in small arteries (the central artery of the ear). The perfusion fixation method at physiological pressure and temperature was used. Both local and systemic effects of 5-FU on endothelium were studied 1, 3, 7, 14 and 30 days after in vivo treatment with 5-FU. Fifteen rabbits were used and five additional animals served as controls. The following parameters …

Angiogenesis In The Gonadal Capillary Network Of The Chick Embryo, F. J. Pérez-Aparicio, A. Carretero, M. Navarro, J. Ruberte

Scanning Microscopy

Seventy-one chick embryos of both sexes at the 35 Hamburger and Hamilton (H-H) developmental stage were processed for scanning electron microscopy of vascular corrosion casts and of critical point dried specimens, as well as transmission electron- and light microscopy, in order to study the angiogenic structures. The gonadal subepithelial capillary network was located at the level of the tunica albuginea under the covering epithelium. The casts showed a densely-meshed capillary network and numerous sprouting (nodular protrusions or capillary sprouts) and non-sprouting (enlarged vessels and angiogenic holes) angiogenic structures that were randomly distributed and mixed. Four types of angio-genic holes were …

Immunogold Labeling For The Diagnosis Of Leukemia By Transmission And Scanning Electron Microscopy, Etienne De Harven, Davide Soligo, Hilary Christensen

Scanning Microscopy

For the cell type diagnosis of leukemia in adult patients, particularly when the sampling of bone marrow is difficult, the study of peripheral blood leukocytes (PBLs) by immuno-electron microscopy provides significant information, as illustrated here in two cases of hairy cell leukemia and seven cases tentatively identified as megakaryoblastic leukemia (M7). Indirect immunogold labeling with the B-ly7 monoclonal antibody (CD103) proved valuable in confirming the diagnosis of hairy cell leukemia. Immunogold labeling for the GplIIa platelet glycoprotein (CD61) was used in cases where the light microscopy of blood films revealed possible megakaryoblastic leukemia. Under the electron microscope, however, the CD61 …

The Effect Of Ionizing Irradiation On Type I Collagen Of The Tail In Growing Mice: A Histology And Electron Microscopy Study, M. Q. Yang, E. Kjellén, C. H. Håkansson, M. Palmegren

Scanning Microscopy

In order to examine the effect of radiation on growing tissue, especially the fibroblasts and their end-product, the collagen fibres, tails from 24 mice were irradiated at an age of 8 days with 20 Gy and 30 Gy (>°Co). Tails from 18 animals served as controls. Six mice from each group were sacrificed on day 8, 20 and 30. Transmission electron microscopy was used to examine the fibroblasts and the collagen fibrils. Non-irradiated fibroblasts had a nucleus rich in chromatin and an abundant endoplasmic reticulum with cistemae and condensing vacuoles.

On day 20, approximately 50 % , and on …

The Influence Of 5-Fluorouracil On The Endothelium In Small Arteries. An Electron Microscopic Study In Rabbits, M. Cwikiel, B. Zhang, J. Eskilsson, J. B. Wieslander, M. Albertsson

Scanning Microscopy

5-Fluorouracil (5-FU) is a widely used antineoplastic agent. 5-FU induced cardiotoxicity is a still relatively unknown side-effect of this drug. This phenomenon could be due to a direct cytotoxic effect on the endothelial cells. We tested this hypothesis in an experimental study in rabbits, by scanning or transmission electron microscopic evaluation of endothelium in small arteries (the central artery of the ear) after in vivo treatment with 5-FU. Both local and systemic effects of 5-FU on endothelium were studied 15, 30, 60 and 120 minutes after intra-arterial or intraperitoneal treatment. Perfusion fixation at physiological pressure and temperature was used in …

Etiology Of Calcium Oxalate Nephrolithiasis In Rats. Ii. The Role Of The Papilla In Stone Formation, W. C. De Bruijn, E. R. Boevé, P. R. W. A. Van Run, P. P. M. C. Van Miert, R. De Water, J. C. Romijn, C. F. Verkoelen, L. C. Cao, J. M. Van 'T Noordende, F. H. Schröder

Scanning Microscopy

In kidneys of healthy rats submitted to a crystal-inducing diet (CID) with ethylene glycol (EG) and NH₄Cl, the fate of retained crystals in the papillar region is studied during a recovery period of one, five or ten days, as model system for human nephrolithiasis. Scanning electron microscopy (SEM) shows, at papillary tips bulging into the calycine space, crystal masses covered either by the epithelium or a thin fibrous veil, or by unidentified mobile cuboidal cells. After CID plus one or five days recovery, small sub-epithelial swellings are seen of large sub-epithelial crystals at or around the papillary tip. …

Etiology Of Calcium Oxalate Nephrolithiasis In Rats. I. Can This Be A Model For Human Stone Formation?, W. C. De Bruijn, E. R. Boevé, P. R. W. A. Van Run, P. P. M. C. Van Miert, R. De Water, J. C. Romijn, C. F. Verkoelen, L. C. Cao, F. H. Schröder

Scanning Microscopy

Crystal retention is studied in a rat-model system as a possible mechanism for the etiology of human nephrolithiasis. A crystal-inducing diet (CID) of ethylene glycol plus NH₄Cl in their drinking-water is offered to healthy rats to generate intratubular crystals. Subsequently, the fate of retained crystals is investigated by allowing the rats a tissue recovery/crystalluria phase for three, five and ten days, respectively, on normal drinking water.

The process of exotubulosis is observed in cortex and medulla of aldehyde-fixed kidneys after three days recovery. After five days, crystals are predominantly seen there in the interstitium. After ten days, cortex …

Notes On The Microstructure Of The Nautilus Shell, P. R. Mitchell, P. P. Phakey

Scanning Microscopy

The shell of the Nautilus was examined using scanning electron microscopy, transmission electron microscopy and polarized light microscopy. The structure consisted of two major layers: a porcellaneous outer layer and a nacreous inner layer. Most of the porcellaneous layer was composed of granular crystals randomly distributed with a substructure suggestive of bundles of acicular crystallites. A separate prismatic sublayer of the porcellaneous material was composed of a more regular arrangement of crystals. The nacre was composed of alternating crystalline lamellae and films of organic material. The lamellae were formed of many polygonal crystal platelets. The growth surface of the nacre …

Strain Relaxation In Graded Ingaas And Inp Buffer Layers On Gaas (001), K. Eberl, K. Häusler, T. Shitara, Y. Kershaw, W. Sigle

Scanning Microscopy

We investigate compositionally graded In_xo≤x≤0.5Ga_1-xAs and InP buffer layers which are prepared by molecular beam epitaxy on (001) GaAs substrate. The initial In content x_o is equal to 0, 0.12, 0.18, 0.24, and 0.5 for the different samples. The In composition of the graded buffer increases linearly between x_o and 0.5 with a fixed slope of 50% In-content per μm. The idea was to combine the advantage of surface flatness in homogeneous buffer layers and the reduced density of threading dislocations on the surface for graded buffer layers. The best compromise in terms of …

Dislocation Nucleation And Propagation In Semiconductor Heterostructures, D. Cherns, S. Mylonas, C. T. Chou, J. Wu, D. E. Ashenford, B. Lunn

Scanning Microscopy

This paper considers misfit dislocation nucleation and propagation in dilute magnetic semiconductor heterostructures in the CdTe-ZnTe-MnTe system. It is shown that, where the deposit is in tension, 1/2 < 110 > dislocations with inclined Burgers vectors propagate by glide along interfacial < 110 > directions and may dissociate giving intrinsic stacking faults. In cases where the deposit is in compression, 1/2 < 110 > dislocations show no evidence of dissociation and propagate by extensive cross-slip to give networks of dislocations close to interfacial < 100 > directions.

Evidence for dislocation sources in ZnTe/GaSb films is presented. ZnTe films contained stacking fault pyramids, single Frank faults and a new type of "diamond defect" …

The Morphology And Misfit Dislocation Formation Characteristics Of Strained Heteroepitaxial Layers: Ex Situ And In Situ Growth Studies, A. G. Cullis

Scanning Microscopy

Under certain regimes of heteroepitaxial layer growth, misfit stresses can lead to very significant distortions in interface morphology, which can influence strain relief and subsequent misfit dislocation introduction. These phenomena have been clearly demonstrated in the case of SiGe/Si heteroepitaxy and the way in which surface SiGe growth ripples are accompanied by strain waves has been established. The ripples provide partial elastic relief of the layer misfit stress in a manner which has been correlated with theoretical expectations. The local stress variations ultimately may influence the formation and disposition of misfit dislocations in the strained layer structures. The present paper …

Ultrastructure Of Dentin Matrix In Heritable Dentin Defects, J. Waltimo, H. Ranta, P. -L. Lukinmaa

Scanning Microscopy

Heritable dentin defects form a group of diseases which exclusively affect dentin among the various dental tissues. While one type is associated with the generalized connective tissue disorder, osteogenesis imperfecta, other types occur as single traits. The clinical manifestations of the dentin defects vary from insignificant to severe enough to cause aesthetical and functional failure of the teeth. Scanning and transmission electron microscopic studies, reviewed in this paper, have markedly clarified the ultrastructure of the aberrant dentin matrix. Both similar and different changes seem to occur in the various forms of heritable dentin defects. Abnormalities in the appearance and organization …

Balancing Surface Energy Terms For Stable Growth Of Planar Surfaces, M. Albrecht, P. O. Hansson, S. Christiansen, W. Dorsch, H. P. Strunk, E. Bauser

Scanning Microscopy

We investigate the driving forces that determine the growth mode of heteroepitaxial Ge layers grown from solution on Si substrates with orientations (001), (011) and (111) by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Using liquid phase epitaxy, we can study the influences of strain and surface energy terms independently on effects due to limited surface diffusion. In (001) and (011) orientated layers, {111} faceted islands form (Stranski-Krastanov growth). In contrast, (111) orientated layers grow in a two-dimensional step flow growth mode (Frank-van der Merwe growth).

We model these investigations in terms of energy minimisation considering surface energy …

Effects Of Modulated Microwave And X-Ray Irradiation On The Activity And Distribution Of Ca2+-Atpase In Small Intestine Epithelial Cells, Z. Somosy, G. Thuróczy, G. J. Köteles, J. Kovács

Scanning Microscopy

The distribution and activity of Ca²⁺-ATPase were investigated by histochemical methods in small intestine epithelial cells of mice following total body 2450 MHz low frequency (16 Hz) microwave and X-ray irradiation. In the control animals, enzyme activities were found in the brush border and on lateral membranes, including junctional areas of the cells. The enzyme activity of lateral membranes was inhibited by quercetin, a specific inhibitor of Ca²⁺-ATPase.

Immediately after square modulated (16 Hz) 2450 MHz microwave irradiation at 1 mW/cm² power densities, we observed a decreased activity of Ca²⁺-ATPase on the lateral …

Diluted And Undiluted Mercox Severely Destroy Unfixed Endothelial Cells. A Light And Electron Microscopic Study Using Cultured Endothelial Cells And Tadpole Tail Fin Vessels, J. Gassner, A. Lametschwandtner, T. Weiger, H. C. Bauer

Scanning Microscopy

Mercox is a methylmethacrylate-based resin which is widely used for vascular corrosion casting with subsequent scanning electron microscopic analysis. In the present study the effect of undiluted and diluted Mercox (4+1; volume + volume; Mercox: monomeric methylmethacrylate (MMA); 0.02 g catalyst MA/ml Mercox) and methylmethacrylate with and without catalyst MA (0.625 g/10 ml MMA) on fixed and unfixed endothelial cells was studied. Light microscopy (LM) of cultured capillary endothelial cells (ECs), which were replicated with diluted or undiluted Mercox shows degranulation and membrane perturbation of ECs, while no morphological changes occur in glutaraldehyde-prefixed ECs. Scanning electron microscopy (SEM) of replicas …

Etiology Of Experimental Calcium Oxalate Monohydrate Nephrolithiasis In Rats, W. C. De Bruijn, E. R. Boevé, P. R. W. A. Van Run, P. P. M. C. Van Miert, J. C. Romijn, C. F. Verkoelen, L. C. Cao, F. H. Schröder

Scanning Microscopy

In a rat-model system, tubular crystal retention as a possible mechanism for the etiology of nephrolithiasis in man, was studied by conventional transmission electron microscopy. The animals were supplied for nine days with a crystal-inducing diet, with ethylene glycol plus NH₄Cl in their drinking-water. After this induction period, a two day regime with fresh drinking-water was included, to allow crystals to be removed by spontaneous crystalluria. After aldehyde fixation of the rat kidneys, large crystals were seen inside the tubular lumen. The crystals were attached to cell surfaces and covered by neighboring epithelial cells. Some crystals were overgrown …

Ultrastructural Observations Of The Argonaut Shell, P. R. Mitchell, P. P. Phakey, W. A. Rachinger

Scanning Microscopy

An examination of the ultrastructure of the shell of the cephalopod Argonauta Nodosa was carried out using scanning electron microscopy, transmission electron microscopy and polarised light microscopy. The structure of the Argonaut shell was found to consist of an inner and outer prismatic layer separated by a thin central zone which was sparsely occupied by spherulitic crystals. Fluctuations in the width and porosity of the central zone resulted in changes in the shell's opacity and gave rise to the fibrous lines visible in the structure. The central zone was the region of initial growth and was the nucleating point for …

Optimization And Application Of Jet-Freezing, T. Müller, S. Moser, M. Vogt, C. Daugherty, M. V. Parthasarathy

Scanning Microscopy

Cryofixation is considered to be the best method for immobilizing biological material in its natural state. In jet-freezing, the specimen typically is sandwiched between two carriers and kept in place while a coolant is moved very rapidly against the opposite surfaces. The JFD 030 jet-freezing device has been used to optimize the operating parameters. The course of the temperature in place of a specimen was measured with thermocouples and recorded by an IBM-compatible personal computer using a specifically developed software program. Mean cooling rates, over the temperature range of 273K to 173K, achievable with different cryogens, including the non-flammable HCFC …

Contributions Of Electron Microscopy To The Study Of The Hypertrophic Scar And Related Lesions, C. Ward Kischer

Scanning Microscopy

Prior to 1969, only one study of the hypertrophic scar had been done using electron microscopy, and that one used electron diffraction. Since that time, studies using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) have been integral in establishing not only the characteristics of this lesion but in formulating the reasons why the scar develops and how it resolves. The first SEM studies demonstrated a homogeneous, dense dermal matrix which supported the conclusion that the hypertrophic scar and keloid reflected excess collagen. These same studies were integral in identifying the collagen nodule as the basic anatomical unit of …

Observations On The Enamel Of Odontomas, Carla Marchetti, Cesare Piacentini, Paolo Menghini, Marcella Reguzzoni

Scanning Microscopy

The morphological study of odontomas provides an alternative model for observing the formation of dental tissues, since different maturing stages are present simultaneously. Investigations were performed on decalcified samples (using light microscopy and transmission electron microscopy) and on undecalcified samples of complex odontoma enamel (using transmission electron microscopy). Simultaneous presence of prismatic enamel at various maturing stages with different structural characteristics was observed. Such enamel was sometimes associated with layers of ameloblastic cells with characteristics of cells in functional activity. In other sites, the enamel did not present a prismatic structure but it appeared as unstructured material clusters with abundant …

Casting With Mercox-Methylmethacrylic Acid Mixtures Causes Plastic Sheets On Elastic Arteries. A Scanning And Transmission Electron Microscopic Study, Seyedhossein Aharinejad, Peter Böck

Scanning Microscopy

Lungs and systemic vessels of rats were cast with Mercox, both undiluted and diluted with monomeric methylmethycrylate (MMA; v:v/4:1), and studied by scanning electron microscopy (SEM). A sheet, less than 5 μm thick, surrounded the surface of cast pulmonary arteries and the aorta, when using diluted Mercox. This envelope was absent when casts were prepared with undiluted Mercox. Transmission electron microscopy (TEM) of unmacerated cast arteries showed all constituents of the vascular wall. Sections of thoroughly macerated vascular casts, however, still showed elastic lamellae in the vascular wall region, whereas muscular components and endothelial lining were completely digested. It is …

Transmission Electron Microscopy And Nanoprobe Analysis Of Ferroelectric Thin Films, Maria Huffman, Mowafak M. Al-Jassim, Chuck Echer

Scanning Microscopy

Thin-film ceramic materials have a variety of electronic applications. Several deposition techniques are currently being used to produce such films with specific properties. For example, rf-sputtered ferroelectric perovskite films, with total thicknesses less than 0.5 μ.m, are being integrated with semiconductor devices as elements for non-volatile memories. Since there is a definite need to characterize these thin films after deposition, electron microscopy has been utilized as one of the most powerful techniques available for examining their morphology and microstructure. Transmission electron microscopy (TEM) examination of these oxides proved difficult. New TEM sample preparation techniques had to be developed in order …

Calcospherites In Rabbit Incisor Predentin, H. Mishima, Y. Kunuki, T. Sakae, Y. Kozawa, N. Watabe

Scanning Microscopy

Calcospherites from the lower incisor dentin of rabbits were investigated by scanning and transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and electron diffraction analyses. In the labial predentin, globular calcospherites of 8-31 μm were present at the root apex, decreasing in size toward the incisal region. The calcospherites at the intermediate region were of mulberry- as well as of spindle-shape of 1.5-4 μm diameter. The incisal pulp horn contained micro-calcospherites of 0.3-0.6 μmin diameter. In the lingual predentin, small granular calcospherites of 1. 8-3 μm were present at the root apex, increasing in size toward the intermediate region. Ultrathin …

Mercox®-Methylmethacrylic Acid Mixture Penetrates Into Cells. A Scanning And Transmission Electron Microscopic Study, S. Aharinejad, P. Böck

Scanning Microscopy

During preparation of vascular casts using mixtures of Mercox® and methylmethacrylic acid for scanning electron microscopy, occasionally irregular structures were observed adhering to otherwise well prepared corrosion casts. These artifacts were further analyzed in sections of cast preparations. The bizarre-shaped structures varied in size and were often tightly connected to vascular casts; they withstood KOH maceration and cleaning with formic acid. The persistence of biological material, connective tissue fibers and cells or cellular fragments, became obvious in ultrathin sections. Transmission electron microscopy also showed inhomogeneity of the polymerized casting medium (Mercox®-methylmetbacrylate mixture; v/v: 4:1). An unidentified com-pound of this resin …

Effect Of Chronic Treatment With Diuretics On Mouse Liver: A Morphological And Microanalytical Investigation, Ann-Christin Mork, Anne Von Euler, Godfried M. Roomans

Scanning Microscopy

In an attempt to produce an animal model for the disease cystic fibrosis (CF), mice were treated chronically with the diuretics amiloride and furosemide, in order to cause chronic inhibition of transepithelial ion transport. Experiments were carried out on adult mice (2 months treatment); in addition, pregnant mice were treated with diuretics, and tissue from offspring 2 and 7 days post partum was investigated. Since biliary cirrhosis is a common occurrence in CF, hepatocytes in the treated mice were investigated by X-ray microanalysis and by light and electron microscopy.

Treatment with amiloride caused a significant decrease in cellular Na concentration …

Response Of The Esophageal Epithelium To Concomitant Cis-Dichlorodiammineplatinum(Ii) And Radiation Treatment. An Electron Microscopic Study In Rabbits, M. Albertsson, M. Cwikiel, C. H. Håkansson, M. Palmegren

Scanning Microscopy

The rabbit esophageal mucosa was irradiated with daily fractions of 2 Gy up to an accumulated dose of 20 Gy (total dose 2, 6, 10. 16 or 20 Gy). Fifteen to forty-five minutes before the start of each irradiation 0.3 mg Cis-dichlorodiammineplatinum (cis-DDP, cisplatinum) was given by intraperitoneal injection to each rabbit. Examinations were carried out 1-10 days after each fractionation schedule, when specimens were taken for morphological investigations.

Scanning electron microscope (SEM) examination showed a gradual development of damage with cell loss and structural disarrangement of the microridges and whorls on the surface. However, with further treatment the esophageal …

Direct Visualization And Silver Enhancement Of Ultra-Small Antibody-Bound Gold Particles On Immunolabeled Ultrathin Resin Sections, York-Dieter Stierhof, Bruno M. Humbel, Rene Hermann, Max T. Otten, Heinz Schwarz

Scanning Microscopy

Ultra-small gold colloids bound to immunolabeled ultrathin resin sections were visualized using transmission, scanning, and scanning transmission electron microscopy (TEM, SEM, STEM). The best marker contrast is obtained in a field emission STEM (200 kV) equipped with a high-angle annular dark-field (HAADF) detector. HAADF STEM renders possible the simultaneous visualization of ultra-small gold and ultrastructural details in unstained resin sections, and an overall presentation of a labeled E. coli cell.

For routine work, an enhancement step is a prerequisite for easy detection of bound marker molecules. Five different silver enhancing solutions were tested for their suitability for ultra-small gold intensification. …

The Effect On The Ultrastructure Of Dental Enamel Of Excimer-Dye, Argon-Ion And Co2 Lasers, J. Palamara, P. P. Phakey, H. J. Orams, W. A. Rachinger

Scanning Microscopy

This study aimed to investigate the ultrastructural changes that occur in dental enamel irradiated with pulsed excimer-dye, continuous-wave (CW) argon-ion and CW CO2 lasers. The pulsed excimer-dye laser produced deep craters, rough damaged surfaces with underlying porosity and amorphous vitrified material. The vitrification of the enamel indicated that the temperature in these areas must have been al least in the range 1280 to 1600°C. The CW argon-ion laser irradiation produced a changed non-cratered surface with inter-crystalline porosity and a mixture of small and some large irregularly packed recrystallized enamel crystals. The CW CO2 laser produced shallow craters, surface crazing and …

Luminal Constrictions On Corrosion Casts Of Capillaries And Postcapillary Venules In Rat Exocrine Pancreas Correspond To Pericyte Processes, Seyedhossein Aharinejad, Peter Böck

Scanning Microscopy

The rat exocrine pancreas was studied as a model to demonstrate morphological features of different types of capillaries, using scanning electron microscopy of vascular corrosion casts and transmission electron microscopy of tissue sections. Two types of capillaries were discerned. The first type represents less undulated, slender, straight capillaries with numerous, shallow, circular or semilunar furrows on its cast's surface. In tissue sections, this type probably corresponds to non-fenestrated capillaries. The numerous grooves on its cast correspond to pericyte processes beneath the endothelial lining. The second type comprises capillaries of an undulated course and variable diameter with less numerous furrows. In …