bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron Microscopy of the Shape of Small Metal Particles
Authors: Yacaman M. Jose
Published: June 2020

In the Study of small metal particles the shape is a very Important parameter. Using electron microscopy Ino and Owaga(l) have studied the shape of twinned particles of gold. In that work electron diffraction and contrast (dark field) experiments were used to produce models of a crystal particle. In this work we report a method which can give direct information about the shape of an small metal particle in the amstrong- size range with high resolution. The diffraction pattern of a sample containing small metal particles contains in general several systematic and non- systematic reflections and a two-beam condition can not be used in practice. However a N-beam condition produces a reduced extinction distance. On the other hand if a beam is out of the bragg condition the effective extinction distance is even more reduced.
Effect of Copper Ion Concentration on the Structure of Copper Deposits Cemented on Pure Aluminum Discs: A Scanning Electron Microscopic Study
Authors: Annamalai V. , Murr L.E.
Published: June 2020

Copper from leach liquors is recovered commercially by cementing elemental copper on scrap iron. Consumption of scrap iron in the cementation reactions is usually much higher than the theoretically required amount1. Aluminum in the form of beverage and beer cans have been tried as a substitute for scrap iron in the copper cementation process, and MacKinnon and Ingraham2,3 were the first to report the experimental results. The rate of a cementation reaction is computed using the first-order rate equation4, and the specific rate constant (k0, cm sec-1) of the reaction is proportional to the effective cathodic surface area. The change in the rate, therefore, is a function of the deposit structure and morphology. A knowledge of the optimum copper ion concentration ([Cu2+]) value for a maximum rate at ambient temperatures is a desirable factor for any cementation process. This paper reports the structural studies of the copper deposits in the copper-pure aluminum system for various initial [Cu2+] values at ambient temperatures.
Molecular Structure of the Outermost Cell Wall Component of Spirillum Serpens
Authors: Chiu Wah , Grano David
Published: June 2020

The periodic structure external to the outer membrane of Spirillum serpens VHA has been isolated by similar procedures to those used by Buckmire and Murray (1). From SDS gel electrophoresis, we have found that the isolated fragments contain several protein components, and that the crystalline structure is composed of a glycoprotein component with a molecular weight of ∽ 140,000 daltons (2). Under an electron microscopic examination, we have visualized the hexagonally-packed glycoprotein subunits, as well as the bilayer profile of the outer membrane. In this paper, we will discuss some structural aspects of the crystalline glycoproteins, based on computer-reconstructed images of the external cell wall fragments.

The specimens were prepared for electron microscopy in two ways: negatively stained with 1% PTA, and maintained in a frozen-hydrated state (3). The micrographs were taken with a JEM-100B electron microscope with a field emission gun. The minimum exposure technique was essential for imaging the frozen- hydrated specimens.
Redistribution of Membranes during Conidiogeneses and Nuclear Development in Verticillium Dahliae
Authors: Mayfield J. E. , Tolmsoff W. J. , Wheeler M. H.
Published: June 2020

Verticil1ium dahliaeis an asexual fungus that produces unicellular, mononucleate conidia as its primary means of reproduction. For conidial formation, specialized hyphal cells convert into verticillate conidiophores, bearing tapered phialides. A conidium develops from the phialide as a protrusion through the terminal pore. Each phialide has a single nucleus that divides repeatedly during the sequential production of numerous conidia. Nuclear material has been found to migrate into developing conidia just before their separation from the phialide tip (1). The present report suggests a possible mechanism for nuclear division and migration.

The ultrastructure of phialides and developing conidia ofV. dahliaewas examined from a narrow zone 5 mm behind the periphery of colonies grown on potato-carrot-dextrose agar. Cells were fixed with 3l glutaraldehyde in cacodylate buffer (pH 6.8) at room temperature, postfixed in cold 2% OsO4in the same buffer, and thin sections were counter stained with 2% uranyl acetate and lead citrate.
Cytochemical Studies of Biogenic Amines
Authors: Wood Joe
Published: June 2020

The electron microscopic localization of biogenic amine neurotransmitters can provide for a definitive approach to the study of these chemical agents in relation to the neuroanatomical substrate of the nervous system. Therefore, if one can specifically identify a neurotransmitter within certain ultrastructural nervous system components then a better understanding is developed of the chemico-morphologic functional relationships. Thus one can develop further the concepts of the chemical interactions within the nervous system.

The localization technique must be chemically specific for a particular compound yet must be so conducted that it produces relatively little artifact or damage within the tissue to disturb the morphological integrity. The cytochemical localization of the agent should possess contrast either in density or chemical configuration so that it can be specifically identified even after the tissue is treated with a relatively nonspecific agent such as osmium tetroxide or is stained after sectioning with conventional stains such as uranyl acetate and/or lead citrate.
Localization of gp70 and p30 Murine Type C. Virus Antigens in Thin Section Electron Microscopy Using Novel Immunolatex Spheres and Comparison with Immunoferritin and Immunoperoxidase Methods
Authors: Gonda M.A. , Hager H. , Oroszlan S. , Gilden R.V. , Hsu K.C.
Published: June 2020

Mammalian type C RNA tumor viruses are composed of several structural proteins that can be identified by molecular weight and location on the virion (1). Rauscher leukemia virus (RLV), a murine type C virus, has a 70,000 dalton glycoprotein (gp70) in its envelope and a 30,000 dalton core protein (p30) as two of its major structural proteins (1,2). Synthetic latex microspheres have been shown to be useful surface markers for the scanning electron microscope (SEM) (3). Presented here is a thin section method utilizing novel latex spheres containing aromatic amines which, when coupled to antibodies by diazotization, act as electron-dense markers for indirect immunoelectron microscopic (IEM) detection of gp70 and p30 antigens of RLV. These results are compared with those obtained by immunoferritin and immunoperoxidase methods.

RLV-infected murine JLSV-10 cells were used for all IEM. All reactions prior to fixation were carried out at 4°C. Pelleted cells were resuspended in primary serum, either goat anti-RLV p30, goat anti-RLV gp70, or normal goat, and allowed to react for 30 min. Cells were washed and sedimented 3X in buffer. Cell pellets for indirect immunolatex labeling were resuspended and gently agitated for 30 min in donkey anti-goat IgG coupled to latex spheres.
A Comparison of the Surface Morphology of Milk-Derived and Tissue Culture- Grown Mouse Mammary Tumor Virus
Authors: Sarkar Nurul H. , Demsey Anthony
Published: June 2020

When examined in the electron microscope by negative staining and thin sectioning, the surface morphology of the murine mammary tumor virus (MuMTV) obtained from murine mammary tumor cells grown in tissue culture appears to be similar to that of MuMTV obtained from mouse milk. The viral envelope appears to be covered by evenly spaced projections consisting of stalks and knobs. The diameter of the knobs is about 5 nm and the projections are approximately 8 nm apart. However, when milk derived MuMTV is examined using the freeze-drying and freeze-etching techniques, no surface projections can be seen. Instead, the surface appears to be covered with evenly spaced inden tations or pits (1,2). By freeze-drying intact murine mammary tumor cells growing in tissue culture, Demsey et al. (3,4) observed protrusions on the surface of MuMTV particles budding from the cell's surface.
Ultrastructural Examination of T1 Virus by High Resolution SEM
Authors: Panessa Barbara J. , Broers Alec N.
Published: June 2020

This non-contractile coliphage has a small capsid, slender hollow tail and lacks an end-plate as well as tail fibers. The work presented here shows the first scanning electron micrographs of intact adsorbed T1 coliphages and demonstrates the presence of repeating morphological subunits comprising the tail which supports the hypothesis of Bradley1. New morphological data about adsorbed phage particles are also revealed.

Virus particles were added to log phase E. coli B on agar-goated Si02 slivers, or in nutrient broth, incubated for 10 or 15 minutes at 30°C and fixed in 1.5% glutaraldehyde in 0.1 M cacodylate buffer (pH 7.2). Samples were dried by the critical point method (C02), metal coated (2-5 nm Au-Pd), and examined using the low-loss mode of operation2 in an SEM having a condenser-objective final lens and a lanthanum hexaboride gun3. An accelerating potential of 45KV was used and a beam diameter below 10Å.
Transmission Electron Microscopic Evidence of Rhopheocytosis as the Mechanism of Melanosome Transfer in Human Hair Bulbs
Authors: Harris Ronald T.
Published: June 2020

Rhopheocytosis is a term first proposed by Marcel Bessis in 1956 to describe the apparent cytophagocytic phenomenon in erythroblast islands of red bone marrow. In this system, rhopheocytosis has been demonstrated to be the mechanism by which ferritin is transferred from reticulum cells (island cells) to erythroblasts. Subsequent to these early studies, the mechanism had not been observed in any other mammalian tissue. The present paper reports TEM evidence that rhopheocytosis is the mechanism by which melanosomes are transferred to living germinal matrix cells in human hair bulbs.

Melanin pigmentation in human scalp hair results from the intimate interaction between neural crest-derived melanocytes and epidermis-derived germinal matrix cells. The major functions of melanocytes are to synthesize the pigment melanin from the amino acids tyrosine and phenylalanine, to deposit this substance on a protein-phospholipid structural framework, and to package the complex in granules, the so-called melanosomes.
Structural Homology between Prokaryotic and Eukaryotic Ribosomes
Authors: Boublik M. , Hellmann W. , Jenkins F.
Published: June 2020

The structural complexity of ribosomes is evident from the large number of their constituents - ribosomal proteins and ribonucleic acids. The simplest known prokaryotic (70S) ribosome from E. coli is composed of 53 different proteins and three ribonucleic acid molecules (23S, 16S and 5S RNA). Eukaryotic (80S) ribosomes also consist of three RNAs (28S, 18S and 5S) but contain a higher number of proteins, approximately 70. The mutual interactions of ribosomal proteins and RNAs determine the final structure and thus the biological activity of the ribosome. As expected for particles with the above composition, ribosomes and both ribosomal subunits have no symmetry or repetition in structure.

Electron micrographs of ribosomes (stained with 0.5% aqueous uranyl acetate and deposited on a fine carbon support) show distinct contours and electron dense pattern. Critical evaluation of different views of the two-dimensional projections of the ribosomal contours can provide a reasonable basis for proposing a three-dimensional model of the ribosome.
Ultrastructural Localization of NA+-K+ -Atpase in Rabbit Cornea Using 5-Nitroindoxyl Phosphate as Substrate
Authors: Tsou K. C. , Khatami Mahin
Published: June 2020

Recently, Leunberger and Novikoff (1) have shown that the endothelial cells are the primary sites of Na+-K+-ATPase, a key mechanism in the control of hydration of cornea. Since this enzyme would be a useful marker for our study of endothelial damage by CO2 laser (2), we have undertaken a comparative study for the localization of this enzyme at ultrastructural level with different methods. In the course of this work we developed a new method with the use of 5-nitroindoxyl phosphate as a synthetic substrate. This new substrate, like p-nitrophenyl phosphate (3), meets the requirements for the demonstration of the K+ activated step of dephosphorylation of ATPase. In addition, it can be used with glutaraldehyde fixed tissue, thereby offering an important advantage over the previous method (3).

Rabbit corneas were freshly excised under pentobarbitol anesthesia.
Immuno-Enzyme Histochemistry of Creatine Phosphokinase
Authors: Baba N. , Poe E.T. , Scillian J. , Myser T.
Published: June 2020

With a commercially available rabbit muscle (MM) type isoenzyme of the creatine phosphokinase (CPK) (Worthington Biochemical), anti-CPK antibody was produced in chicken and goat (Figure 1). Fab' fragments of the chicken and goat IgG were isolated and conjugated with a commercially available horseradish peroxidase (HRP) according to the Nakane method (J. Histochem. Cytochem,, 22:1084, 1974).

Rabbit hearts were perfused in vivo with freshly prepared 2% paraformaldehyde solution, and the left ventricular myocardium was fixed for 30 minutes. Forty-micrometer-thick frozen sections of the myocardium were incubated with the Fab'-HRP conjugate overnight at 4°C. After a thorough rinse, the sections were stained for the peroxidase reaction.

In an electron microscope, diffuse cytoplasmic staining of the heart muscle cells was noted, indicating the diffuse cytosol distribution of CPK (Figure 2). In addition, there was strong staining of the intermembranous and intracristal space of the mitochondria as well as the M-lines of the myofibrils (Figures 3 and 4).
Adrenocorticotropin Production by a Mammary Carcinoma
Authors: McCarty K.S. , Wallace N.R. , Litaker W. , Wells S. , Eisenbarth G.
Published: June 2020

The production of adrenocorticotropic hormone by non-pituitary carcinomas has been documented in several tumors, most frequently small cell carcinoma of the lung, islet cell carcinomas of the pancreas, thymomas and carcinoids. Electron microscopy of these tumors reveals typical membrane-limited "neurosecretory" granules. Confirmation of the granules as adrenocorticotropin (ACTH) requires the use of OsO4 as a primary fixative to give the characteristic cored granule appearance in conjunction with immunohistochemical demonstration of the hormone peptide. Because of the rarity of ectopic ACTH production by mammary carcinomas and the absence of appropriate ultrastructural studies in the two examples of such ectopic hormone production in the literature of which we are aware (1,2), we present biochemical and ultrastructural data from a carcinoma of the breast with apparent ACTH production.

The patient had her primary tumor in the right breast in 1969. The tumor recurred as visceral and subcutaneous metastases in 1976 and again in 1977.
Destruction of Actin Filaments by Osmium Tetroxide
Authors: Maupin-Szamier P. , Pollard T. D.
Published: June 2020

We have studied the destruction of rabbit muscle actin filaments by osmium tetroxide (OSO4) to develop methods which will preserve the structure of actin filaments during preparation for transmission electron microscopy.

Negatively stained F-actin, which appears as smooth, gently curved filaments in control samples (Fig. 1a), acquire an angular, distorted profile and break into progressively shorter pieces after exposure to OSO4 (Fig. 1b,c). We followed the time course of the reaction with viscometry since it is a simple, quantitative method to assess filament integrity. The difference in rates of decay in viscosity of polymerized actin solutions after the addition of four concentrations of OSO4 is illustrated in Fig. 2. Viscometry indicated that the rate of actin filament destruction is also dependent upon temperature, buffer type, buffer concentration, and pH, and requires the continued presence of OSO4. The conditions most favorable to filament preservation are fixation in a low concentration of OSO4 for a short time at 0°C in 100mM sodium phosphate buffer, pH 6.0.
Cytoplasmic Filaments in the Chick Lens Fiber Cells
Authors: Bradley Ronald H. , Alcala Jose , Maisel Harry
Published: June 2020

Filaments (average diameter, 12 nm) are a prominent feature of the water- insoluble fraction of chick lens fiber cells (1) (fig. 1). Isolation of the filaments was achieved in the following manner. The lens fiber mass was homogenized in standard salt solution pH 7.2 to which 10 mM B-mercaptoethanol was added. The homogenate was centrifuged at 37,000 g for 20 min. and the pellet washed in buffer until free of soluble proteins (lens crystallins) when tested with antisera to the crystallins. The pellet was then extracted in 8M urea and centrifuged at 77,000 g for 15 min. The membrane-rich pellet was discarded and the urea-soluble fraction was dialysed against the buffer to remove the urea. Negative stain analysis showed that intact filaments were present in the urea-free solution (UFS).

A pellet rich in filaments was obtained by centrifugation of the UFS at 77,000 g for 1 hr. (fig. 2).
A Complex Glycoprotein Released from Platelets by Thrombin Action
Authors: Lawler John W. , Slayter Henry S.
Published: June 2020

Human blood platelets contain a glycoprotein previously called thrombin sensitive protein (TSP) which is released into the extracellular environment as a result of the action of thrombin. TSP had been variously reported to be 150,000 to 190,000 daltons (1) by SDS polyacrylamide gel electrophoresis. A recent report (2) has indicated that TSP is really a 150,000 dalton component produced by reduction of a 450,000 dalton complex macro- glycopeptide, which we have now isolated. We shall call this glycoprotein thrombospondin (TSN) (because it is liberated intact by the action of thrombin from blood platelets), in order to distinguish it from its more commonly identified subunits which may or may not be identical chemically, to each other.

TSN is purified by treatment of fresh washed platelets with 3U/ml of thrombin, followed by hirudin treatment to stop thrombin action, and subsequent removal of platelets by centrifugation.
Cell Surface Markers and Labeling Techniques for Scanning Electron Microscopy
Authors: Molday R.S.
Published: June 2020

Cell surface labeling has provided valuable information on the organization and dynamics of specific antigens and receptors in cell membranes. Such studies have generally utilized fluorescent dyes, radioisotopes, enzymes or biological macromolecules (ferritin, hemocyanin, viruses) bound to specific ligands (antibodies, lectins, hormones and toxins) as visual probes for light and transmission electron microscopy (TEM). More recently, visual markers and labeling methods have been developed for scanning electron microscopy (SEM). These techniques have been used to map the topographical distribution of specific molecules on complex cell surfaces (1).

Visualization of cell labeling by SEM relies on the use of macromolecular markers which are resolvable under the SEM. Such markers also must i) be uniform in size and shape to facilitate their identification on cell surfaces, ii) show little, if any, nonspecific binding to cell surfaces, iii) interact with surface specific ligands via covalent bonding or high affinity binding and iv) be stable against degradation or aggregation during labeling and preparation of samples for SEM.
Cell Surface Characteristics of a Human Breast Carcinoma Cell Line (MCF-7)
Authors: Russo J. , Russo I.
Published: June 2020

Modifications of the acid mucopolysaccharide coat of mammalian cells is considered an important marker of cell transformation in vitro.

In the present paper, the ultrastructural localization of acid mucopolysaccharides on the cell surface of MCF-7 cells is reported. MCF-7 is a cell line derived from a metastatic human breast carcinoma which has been cultured in monolayer in Eagle's minimum essential medium for more than five years. Cells growing in monolayer for more than 142 transfers and cells of the same transfer seeded in collagen-coated cellulose sponges (1) were used in these experiments. Both groups of cells were either rinsed three times in caco- dylate buffer, 0.1 M, pH 7.2, and then fixed and stained with ruthenium red RR (2), or labeled and fixed with cationized ferritin (CF) according to Danon's (3).

All the cells growing in monolayer had a continuous electron-dense fuzzy layer of RR attached to the outer leaflet of the cell membrane at both the free surface and the intercellular spaces (Fig. 1).
Fine Structural Changes in the Adenohypophyses of Rats Following Destruction of the Pituitary Stalk
Authors: Kovacs K. , Horvath E. , Bilbao J. M. , Laszlo F. A. , Domokos I.
Published: June 2020

Electrolytic lesions of the pituitary stalk in rats interrupt adenohypophysial blood flow and result in massive infarction of the anterior lobe. In order to obtain a deeper insight into the morphogenesis of tissue injury and to reveal the sequence of events, a fine structural investigation was undertaken on adenohypophyses of rats at various intervals following destruction of the pituitary stalk.

The pituitary stalk was destroyed electrolytically, with a Horsley-Clarke apparatus on 27 male rats of the R-Amsterdam strain, weighing 180-200 g. Thirty minutes, 1,2,4,6 and 24 hours after surgery the animals were perfused with a glutaraldehyde-formalin solution. The skulls were then opened and the pituitary glands removed. The anterior lobes were fixed in glutaraldehyde-formalin solution, postfixed in osmium tetroxide and embedded in Durcupan. Ultrathin sections were stained with uranyl acetate and lead citrate and investigated with a Philips 300 electron microscope.
Basal Lamina Formation in DMBA Induced Mammary Carcinoma
Authors: Russo I. , Saby J. , Russo J.
Published: June 2020

It has been previously demonstrated that DMBA-induced rat mammary carcinoma originates in the terminal end bud (TEB) of the mammary gland by proliferation of intermediate type cells (1). The earliest lesion identified is the intraductal proliferation (IDP), which gives rise to intraductal carcinomas. These evolve to cribriform, papillary and comedo types (2). In the present work, we report the ultrastructural changes that take place in the IDP for the formation of a cribriform pattern.

Fifty-five-day-old Sprague Dawley virgin female rats were inoculated intra- gastrically with 20 mg 7,12-dimethylbenz(a)anthracene (DMBA) in 1 ml sesame oil. Non-inoculated, age-matched females were used as controls. Mammary glands from both control and experimental rats were removed weekly from the time of inoculation until 86 days post-inoculation. The glands were fixed and processed for electron microscopy (2).

The first change observed in IDP's was the widening of intercellular spaces and the secretion of an electron dense material into these spaces (Fig. 1).
Ruthenium Red as a Ligand of Osmium for Examining Uncoated Biological Material in the Scanning Electron Microscope
Authors: Feria-Velasco Alfredo , Arauz-Contreras Jorge
Published: June 2020

The scanning electron microscope (SEM) has great advantages over the light microscope for examining the surface of cells and tissues, and recently it has been employed for studying the distribution of enzymes and antigens on their surfaces (1). In the basic methodology for preparing specimens to be examined in the SEM, the samples are coated with a 20-40 nm metal layer, usually gold, platinum and palladium. For high resolution SEM purposes, the thinnest possible conducting coat should be used and some authors have employed a 2-5 nm gold coating, omiting the preliminary carbon coating (2). However, some workers using the evaporative metal techniques have encountered difficulties and possible artifacts even with the thinnest evaporated metal layer (3). Various authors have described procedures for examining uncoated specimens, being one of the most useful methods the modified thiocarbohydrazide procedure for SEM (4). In the present work a method for examining the uncoated specimens in the SEM was used by means of osmium tetroxide (OSO4) and employing ruthenium red (RR) as a ligand.
Contamination at Low Temperature
Authors: Wall J. , Bittner J. , Hainfeld J.
Published: June 2020

Contamination of biological specimens has been a practical limitation for many years. It is especially noticeable in the dark field STEM (Scanning Transmission Electron Microscope) since contamination only occurs near the area irradiated by the beam and since we are most often observing very thin specimens (20 - 40 Å). Contamination can be greatly reduced by baking the specimen to 100°C in vacuum prior to observation, (1), but such heating may alter biological structures and cause heavy atom migration away from heavy atom staining sites.

Since contamination results from surface migration (2), it might be eliminated by cooling the specimen to a sufficiently low temperature. The Brookhaven STEM (3).is equipped with a cold stage capable of attaining -170°C with less than 5 Å vibration. Contamination was observed as a function of temperature for a clean carbon film and for two biological specimens. The specimens were prepared on slotted Titanium grids covered by a holey carbon film with thin carbon (˜ 20 A) stretched across the holes.
The Frozen Biological Specimen in Fly Ash Investigations
Authors: Hayes T. L.
Published: June 2020

Fly ash is the major particulate pollutant resulting from coal combustion. These micron and sub-micron sized particles have been shown to contain many toxic chemical elements (1) and the chemical composition can vary greatly from particle to particle. In studying the biological effects which may be associated with these particles, attention to damage to even a single cell is necessary. Carcinogenesis, in particular, may have an initiating event associated with the transformation of a single cell. Both the exposure in terms of variation in single particle chemistry and biological effect in terms of single cell alterations must be measured at the microscopic level rather than relying exclusively on bulk techniques which average the chemical composition of a great number of particles and the damage to a great many cells.

The frozen specimen helps to preserve the chemical properties of the fly ash particles by reducing the number of solvent steps needed during preparation. The biological surface can also be maintained in the frozen specimen with the possibility of either retaining hydration during SEM analysis in .he form of ice or removing the water by freeze drying techniques.
Vesiculation and Loss of the Plasma Membrane along the Midpiece of Physa Sp. Spermatozoon
Authors: Ackerson A. , Koehler L.
Published: June 2020

The Physidae are among the advanced families of the freshwater snails having very extensive and elaborate genital ducts. To achieve cross fertilization the spermatozoon must travel a long distance along a tortuous path through the oviduct and its secretions. The concept that spermatozoon structure is related to the physiological demands of the fertilization environment has been stated previously (1). The present paper describes a specialized structure associated with the plasma membrane and the loss of the plasma membrane along the midpiece of Physa spermatozoa.

In early Physa spermatids, plasma membrane vesiculation is observed concurrently with cellular and nuclear condensation. The midpiece exhibits coiling and folding within the boundaries of the plasma membrane as it develops (Fig. 1). Fig. 2 shows a later stage of maturation in which the plasma membrane becomes closely associated with the midpiece and undergoes extensive vesiculation. The surface of the midpiece is a microtubular sheath.
In situ observation of Dense-Body Release from Hydrated Human Platelets
Authors: Hui S.W. , Costa J.L. , Smith M.A. , Strozewski C.M.
Published: June 2020

Dense bodies, electron-dense granules are believed to be storage sites for large pools of platelet serotonin, pyrophosphate, adenine nucleotides, and calcium. In order to prove that dense bodies exist as such in living platelets, we examined hydrated human platelets in the electron microscope, utilizing the differentially pumped hydration chamber.

Human platelets were resuspended in the sodium chloride-Tris-citrate buffer with 0.35% bovine serum albumin, and were allowed to settle on carbon-coated grids covered with a thin film of liquid. Specimens were viewed and photographed at 100 kV in a Siemens 1A electron microscope equipped with an environmental chamber. The beam dose per micrograph was 5 x 10-5 coulombs/cm2. Although details of some platelets were obscured by a thick film of water, dense bodies were clearly visible in a large proportion of the platelets photographed (Figure 1). The distribution of platelets by dense-body content was similar to that described previously for air-dried whole mounts.
Vascular Defects on Human Endometrium Caused by T-Shaped Copper Intrauterine Devices
Authors: Hohman W. R. , Shaw S. T. , González-Angulo A.
Published: June 2020

Excessive uterine bleeding occurs in many women using intrauterine devices (IUDs), a primary problem preventing worldwide acceptance of this form of contraception. Previously we have studied hysterectomized uteri containing inert, plastic IUDs (primarily Lippes loops and some Saf-T-coils and Dalcon shields) with the electron microscope and found a small percentage of vascular defects accompanied by degenerate endothelial cells located in superficial endometrium (1). In that study, it was determined that surface erosion and chemically mediated permeability were unlikely, therefore we postulated that mechanical effects (pressure, shear) between IUDs and endometrium could directly injure superficial vessels. Such injury could lead to the observed vessel degeneration and gap formation, and provide a feasible routine for uteri bleeding. If this mechanism is valid, smaller IUDs should reduce the magnitude of mechanical stress, reduce the number of vascular gaps, and therefore reduce IUD-induced uterine bleeding.
Effects of Plastic and Copper IUD's on the Epithelial Morphology of the Rat Uterus
Authors: Dyer R. F. , Peppler R. D.
Published: June 2020

The addition of metallic copper to small plastic intrauterine devices increases their efficacy in contraception. The mechanism of action of the copper device is unknown, and numerous studies are attempting to determine the effects of copper on the reproductive system. It has been shown that rats with a copper device in one of the two uterine horns ovulate fewer eggs from the ipsilateral ovary compared with the contralateral ovary. This suggests that the copper may have a direct effect at the ovarian level to reduce follicular development and subsequent ovulation. In contrast, the presence of a plastic device in one horn does not influence ovulation from either ovary.

Since the presence of a copper or plastic device results in different responses in ovulation, the question arises as to the effects of these devices on uterine morphology, especially with regard to the lining epithelium.
Quick-Freezing to Catch the Membrane Changes that Occur During Exocytosis
Authors: Heuser J.E.
Published: June 2020

The technique that we have used to capture synaptic vesicle exocytosis at the frog neuromuscular junction - that of quick-freezing muscles followed by freeze fracture (3) or freeze substitution (6) - works sufficiently well now that it may be useful in other sorts of membrane studies, or studies of fast structural changes with the electron microscope. This note reviews the quickfreezing technique we use, and describes its application to the problem of synaptic vesicle exocytosis and recycling at the synapse.

Here, many of the membrane changes of interest occur during the brief delay in synaptic transmission, on a time scale of milliseconds or fractions of milliseconds, and leave only traces thereafter. In the past, we have studied these left-over traces in tissues fixed with the standard chemicals for electron microscopy (1), and have inferred from them that vesicles discharge the quanta of neurotransmitters, as the physiologists would predict.
Measurement and reduction of damage in frozen hydrated crystalline specimens
Authors: Glaeser Robert M. , Hayward Steven B.
Published: June 2020

Highly ordered or crystalline biological macromolecules become severely damaged and disordered after a brief electron exposure, as may be seen by observing the fading and loss of the specimen's electron diffraction pattern. Loss of the diffraction pattern intensity has, in turn, a one-to-one relationship with a loss of the possibility to see structural information in the image. The actual electron exposure that results in a significant decrease in the diffraction intensity will depend first of all upon the resolution (Bragg spacing) involved, and in some cases upon the chemical make-up and composition of the specimen material. For high resolution features (in the range 3Å to 5Å resolution) of specimens such as protein crystals and cell membranes, the structure can become damaged and disordered after an exposure of about 1 electron/Å2 or less. Roughly speaking, this exposure is about 104 times lower than that which is required to produce a statistically defined image at high resolution.
Morphometry of cell organelles on thick sections by high voltage electron microscopy
Authors: Ohno S. , Yoshida K. , Murata F. , Nagata T.
Published: June 2020

Although the analysis of size distributions of cell organelles on the ultrathin sections is usually carried out by conventional electron microscopy, the procedure brings about some errors. The purpose of this paper is to describe a more useful method for morphometry by high voltage electron microscopy and to demonstrate how this method can be applied to practical problems.

The pituitary,the kidney and the liver of a mouse and rats were used as materials. The pituitary gland was obtained from a male mouse. It was doubly fixed in 2.5% glutaraldehyde and 1% osmium tetroxide,dehydrated with a graded series of ethanol and embedded in Epon. The kidney and the liver were obtained from male rats treated with DEHP ( di-2-ethylhexyl phthalate),a peroxisomes proliferating agent. They were prefixed in 2.5% glutaraldehyde for 3 hours and were incubated in a DAB.pH 9.0,medium containing hydrogen peroxide for 60 minutes at 37°C. They were postfixed in 1% osmium tetroxide, dehydrated and embedded in Epon. Ultrathin (0.lμm), semi thin (0.2μm) and thick(0.5μm, 1.0μm) sections from the same Epon block were cut with an LKB Ultrotome respectively.
An observation of fresh biological samples by high voltage electron microscopy
Authors: Hashimoto Paulo H. , Gotow Takahiro , Takagi Hiroshi , Komatsu Masao , Fujita Hiroshi
Published: June 2020

An environmental cell for a 3 MV-class electron microscope has been developed, and applied mostly to metallurgical subjects. We have modified it slightly, and applied it to some fresh biological samples.

A cross section of the environmental cell and the capsule meshes is schematically drawn in Fig. 1. The two 400 x 100 mesh grids with respective supporting collodion films were coated with evaporated silicon oxide, and attached together with the 400 mesh bars of one at right angles to the 400 mesh bars of the other. In some cases the lower grid was additionally coated with evaporated gold. The grids together with holders A, B, and C were cooled by electric heater controled conduction from a liquid nitrogen container. A platelet-rich plasma of the r a t, and a suspension of Proteus mirabilis were used as fresh biological samples. They were introduced into the environmental cell by a gentle sucking through the pipe (Fig. 1) followed by a continuous ventilation of the atmospheric air. Then the cell was cooled to about -35°C, and the electron beam was emitted with an acceleration voltage of 2 MV. The intensity of the beam was kept as low as possible, and the image could be detected only on a TV screen. The results were recorded on a video tape.
Three dimensional organization of glial cell processes as revealed by high voltage electron microscope stereoscopy
Authors: Hama Kiyoshi , Kosaka Toshio
Published: June 2020

The stereo-observation of biological materials can effectively achieved by the high voltage electron microscope utilizing the high penetration power of electrons at high accelerating voltage which enables the observation of thick specimens, and the large depth of forcus resulted by the small angular aperture used in the electron microscope (Hama, 1972). The high voltage electron microscope was applied to the study of the neuroglial cell processes in the cerebellar cortex of monkey and rat by Chang-Palayand Palay (1972). We investigated further the three dimensional organization of the neuroglial cell processes in the cerebellum and retina of rat by means of high voltage electron microscope stereoscopy.

The Golgi preparations of cerebellar cortex and retina of rat were prepared by the methods described previously (Stell and Lightfoot, 1975; Colonnier, 1964). Plastic sections 100 μm thick were used for the light microscope observation.
High-voltage electron microscopy of adrenal medulla: continuities between organelles
Authors: Carmichael Stephen W. , Smith David J.
Published: June 2020

The adrenal medulla of the cat and rat has been studied during resting and stimulated conditions by high-voltage electron microscopy (HVEM). It was our objective to study the relationship of cytoplasmic organelles to each other and the cytoplasmic membrane system as they participate in the process of secretion.

The adrenals were fixed by vascular perfusion with buffered aldehyde solutions. The perfusion was immediately preceeded by acetylcholine (1 mg/ml) in some cats. In other cats and rats the perfusion was preceeded by insulin (5 IU/kg; IV) at 0, 4, 24, 48, 72 and 96 hr. intervals. The tissue was post-fixed with OsO4, KMn04, K4Fe (CN)6, K2Cr207, ZnIOsO4, Pb and Cu citrate, U acetate, and 3-3' dilminobenzidine singly and in specific combinations. Blocks were dehydrated in acetone and embedded in Epon-Araldite. Ultrathin and thick (0.5 - 2 μm) sections were cut on diamond and glass knives and mounted on carbon-coated copper grids. Specimens were examined at 50-100 KV on conventional TEM and at 800-1000 KV at the HVEM facilities at U.S. Steel Research Laboratory, Monroeville, PA, and University of Colorado, Boulder, CO.
The packing of cowpea chlorotic mottle virus in crystalline monolayers
Authors: Baker Timothy S.
Published: June 2020

Cowpea chlorotic mottle virus (CCMV) is a T=3 icosahedral RNA plant virus of diameter 25-26 nm. The negative staining-carbon film technique provides a useful method for inducing crystallization of the virus into hexagonal or square packed monolayers. This investigation reports an optical and digital analysis of electron micrographs, which shows that the virus packing in square arrays is not the most obvious one.

Figure (a) shows a typical, negatively stained array, obtained by the published procedure. Close inspection reveals that all virus particles are oriented with a two-fold rotation axis normal to the plane of the array. Horne et al. have shown that adjacent particles are aligned at right angles to each other. Thus there are two particles in each unit cell with dimension~37.5 nm (outlined in (a)). The low resolution, apparent primitive lattice is a pseudo-lattice. This is confirmed in the optical diffraction pattern (Fig. b) where the strong, low resolution (<6 nm) spots appear at the pseudo-lattice positions.
Dynamic observation of hydrated biological structures using film-sealed environmental cell method
Authors: Murakami S. , Fukushima K. , Fukami A.
Published: June 2020

Plastic microgrid was successfully adopted in preparing a thin sealing film of the environmental cell as subsidiary window frame. This has made possible to reduce the thickness of carbon sealing film down to 20 nm, and to increase transmission of electron beam up to 60 % at 100 kV. The sealing film is highly durable even under the pressure difference between atmospheric pressure and vacuum, and leakage of gas is negligible (2x10-8 Torr.⥍/sec). Under the conditions used in our film-sealed environmental cell, water surrounding the specimens (e.g., polystyrene particles) in wet ait was remained unvaporized, when relative humidity was kept over 80 % (Fig. 1). Thus, high resolution observations at 3 nm of hydrated biological structures including tobacco mosaic virus, paramyosin paracrystal and thylakoid membranes have been achieved under controlled atmosphere.
An all glass freeze-drier for TEM specimens with an improved design for temperature regulation, fixation and infiltration
Authors: David Coulter H. , Terracio Louis
Published: June 2020

Recent improvements in methods of rapid freezing have revived interest in the use of freeze-drying as a viable alternative to aqueous fixation for transmission electron microscopy. Previous work by the authors using partial pressure analysis of water sublimed from drying tissue has led to the design of an improved freeze-drier. The advantages of this apparatus include speed and ease of operation, accuracy of temperature control, and the fact that the tissue can be dried, fixed, and embedded without breaking vacuum. The primary components of the freeze-drier are shown assembled in Figure 1 at one-fifth actual size. The operational procedure is outlined in detail below.

1) Disconnect the pumping chamber from the apparatus at 0-ring joint G. Remove the valve stem H and preheat the chamber for at least 12 hours at 150° C. Insert the valve stem, close the valve, place the pumping chamber in a 7 inch O.D. Dewar filled with liquid nitrogen (LN), and allow the pump to equilibrate for 4-24 hours.
EM radioautographic studies on the synthesis and transport of phosphatidylcholine in the parotid acinar cells of isoproterenol-treated rats
Authors: Yamashina Shohei
Published: June 2020

The secretory process of the exocrine cells includes: 1) synthesis of secretory materials, 2) intracellular transport and packaging in secretory granules, 3) exocyto- tic discharge responding to secretory stimuli and 4) repair of excess plasma membrane. According to the concept by Palade, synthesis and intracellular transport of secretory products are completed within the surrounding membranes. It is particularly interesting to analyze the dynamic aspects of the membranous container under the brisk stage of secretion granule formation. Since phosphatidylcholine(PC) is well known as one of the ubiquitous constituents of biological membranes, the present study was undertaken to examine the incorporation of [3H]-choline into PC and intracellular movement of labelled PC in the parotid gland of stimulated rats by the administration with isoproterenol (IPR) by means of electron microscopic radioautography,

Female Wistar rats(200g body weight) were injected intraperitoneally with isopro- terenol-HCL(8mg/100g body weight). Every 2 hours ranging from 0 to 24 hours both sides of the parotid glands were removed and dissected into pieces of lobules.
A simplified method of emulsion coating and development for quantitative electron microscopic radioautography
Authors: Yoshida K. , Murata F. , Ohno S. , Nagata T.
Published: June 2020

Introduction

Several methods of mounting emulsion for radioautography at the electron microscopic level have been reported. From the viewpoint of quantitative radioautography, however, there are many critical problems in the procedure to produce radioautographs. For example, it is necessary to apply and develop emulsions in several experimental groups under an identical condition. Moreover, it is necessary to treat a lot of grids at the same time in the dark room for statistical analysis. Since the complicated process and technical difficulties in these procedures are inadequate to conduct a quantitative analysis of many radioautographs at once, many factors may bring about unexpected results. In order to improve these complicated procedures, a simplified dropping method for mass production of radioautographs under an identical condition was previously reported. However, this procedure was not completely satisfactory from the viewpoint of emulsion homogeneity. This paper reports another improved procedure employing wire loops.
An improved method in morphometry of small blood vessels
Authors: Winkler B. , Schaefer H. , Huebner C. , Schaper J.
Published: June 2020

Recently, we developed a new computerized system in morphometry, that consists of a high resolution graphic tablet (Tektronix 4953) directly connected to a PDP 11/45 computer (fig. 1). By tracing a specified contour with a graphic pen the corresponding coordinates on the graphic tablet are stored for further procession in the computer. The density of mesh-points on the graphic tablet is sufficiently high (0.25 mm grid width) to integrate directly a structure area or a borderlength. In contrast to conventional point-counting methods the grid width must not be adapted to the size of the structure. Additionally, the complete definition of a structure by the coordinates of its contour facilitates the evaluation of parameters such as diameters, distances or the centre of gravity.
Specimen course: automated EM specimen processing
Authors: Kölbel Hermann K.
Published: June 2020

Ultrathin sectioning requires a number of preparation steps which may influence and even change the original arrangement and composition of the specimen. The conditions of fixing, dehydration and embedding with divers chemical agents in varying concentrations, different moreover in reaction time, temperature and the kind of their combination and sequence, are so numerous and multifarious that it is difficult to predict significance and value in detail. All recipes usually used in preparative electron microscopy are therefore obtained empirically. An intensive systematic study of the influencing parameters for a given category of specimen is always needed to improve the preservation of specimen structure and to make results more reproducible and comparable.

For this purpose and to meet our own experimental demands, we developed, manufactured and tested an instrument which allows to perform the required steps automatically according to a preselected program.
A comparison of gold and platinum sputtered coatings for scanning electron microscopy
Authors: Watt I.M.
Published: June 2020

It is widely accepted that thin conducting films of noble metals have the desirable properties of high electron emission and high resistance to corrosion which fit them for use as specimen coatings for scanning electron microscopy. However, although Au and its alloys with Pd are regularly used for this purpose, deposited by either evaporation or sputtering, the use of Pt has apparently been ignored. The high evaporation temperature of this metal (2090°C against 1350°C for Au) makes its controlled evaporation inconvenient, but the recent commercial introduction of simple sputter coaters, coupled with developments in Pt plating technology, have made the sputtering of Pt on to SEM specimens a practical proposition. A comparison of the properties of sputtered coatings of Au and Pt has therefore been made; results given below show that satisfactory coatings may be made with Pt as conveniently as with Au, and that in some respects the Pt coatings are superior.
Contrast effects in enamel crystallites
Authors: Marshall A. F. , Lawless K. R.
Published: June 2020

Previous observations on tooth enamel have shown it to be made up of closely packed rod-shaped crystallites of hexagonal hydroxyapatite, which are a few hundred angstroms in cross-section and vary widely in length. Nylen and Frazier have reported the observations by TEM of an electron-dense line in some of these crystallites which is present when the image is defocused, but vanishes at focus. This line was reported to be approximately parallel to the c-axis of longitudinal sections, and to approximately bisect cross-sectioned crystallites. An apparently related observation is that the core of the crystallites, i.e. along the c-axis, is preferentially attacked both by in vitro demineralization and by caries. Lattice images of the crystal planes have been resolved by Nylen and by Selvig, but no relationship of the previously observed dense line to the lattice fringes has been reported.