bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.
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.
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

IntroductionSeveral 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.
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.
Simultaneous observations of immunolabeled frozen sections in lm and em
Authors: Tokuyasu K. T. , Slot J. , Singer S. J. 
Published: June 2020

Immunofluorescent microscopy is more suitable for the analysis of a large number of cells, often greater in the sensitivity for the detection of antigens, and more readily applicable for the identification of multiple antigens than immunoe1ectron microscopy. For combining these features of fluorescent microscopy with the superior resolution of electron microscopy, we attempted to observe the same immunolabeled ultrathin frozen sections with both light and electron microscopy.Ultrathin frozen sections of rat pancreas fixed in a mixture of 2% formaldehyde and 0.2% g1utaraldehyde for 1 hr at 4°C were first immunostained with rabbit anti-rat amylase antibodies, then very lightly with ferritin-goat anti-rabbit IgG conjugates and heavily with rhodamine-goat anti-rabbit IgG conjugates. For light microscopic observation, grids were suspended underneath the cover glass with a very thin layer of 50-90% glycerol and the cover glass was separated from the slide glass by a spacer to avoid the contact of the grid with the slide glass. After the light microscope observation, the grids were floated on 0.1 M phosphate buffer by dissolving glycerol into the buffer and processed for electron microscopy.
Organization of immunoglobulin genes
Authors: Brack CH. , Lenhard-Schuller R. , Traunecker A. , Tonegawa S. 
Published: June 2020

Recent DNA-RNA hybridization experiments suggested that the genes coding for variable (V gene) and constant (C gene) parts of immunoglobulin molecules are separate in embryonic mouse DNA, whereas in lymphocyte DNA they are close together, implying a somatic rearrangement process of the two genes during lymphocyte differentiation. To study mechanisms involved in the organization and expression of Ig genes at a molecular level, we have been cloning DNA fragments containing Ig light chain genes from early embryonic cells and from myeloma cells. We here report electron microscopic characterization of three cloned DNA fragments: two clones from embryonic DNA carrying V gene (Ig 99) and C gene sequences (Ig 25), and one clone from myeloma DNA carrying both V and C genes (Ig 303).R-loop mapping. The purified DNA fragments were hybridized to Ig mRNA (isolated from λ type light chain producing myeloma cells) under conditions of R-loop formation. Measurement of the position and extension of the R-loops allowed us to localize the regions homologous to the Ig mRNA and to construct a preliminary map of the DNA fragments.
Morphology of escherichia coli ribosomes as obtained by high resolution shadow cast
Authors: Tesche B. , Tischendorf G.W. , Stöffler G. 
Published: June 2020

All components (54 proteins and 3 RNA molecules) of the E. coli ribosome have been identified and characterized by biochemical and biophysical means. The morphology of the ribosome and the structural arrangement of its components, however, is not yet unequivocally known. The reasons for this are that crystal arrangements could not be obtained and that the different preparations of single particles remain invariant; and that holds for different laboratories as well.We applied a preparation which has been demonstrated to be most gentle and hence most structure-preserving; that is, freeze-drying with shadow casting at -150°C. Furthermore, the evaporator is of such design that it produces very little heat and renders a thin, fine-grained tungsten layer. An electron optical resolution of 6 Å can be achieved. Fig. 1 shows a micrograph of a typical shadowgraph obtained with 70S ribosomes from which we attempt to derive a three-dimensional model of the ribosome.
Cytochemical and ultrastructural studies on sexual dimorphism of rat liver peroxisomes
Authors: Ohkawa Kin-ichi , Suzuki Yasuhiro 
Published: June 2020

Considerable biochemical evidence has been obtained in connection with sexual differences in the activity of hepatic enzymes such as steroid metabolizing enzymes and catalase, and in the lipid composition of microsomal membranes. In addition to these biochemical findings, a variety of chemicals are also known to induce sex-dependent hepatocellular alterations. Since attempts have apparently not been made to obtain evidence of hepatic sexual dimorphism, we designed the present experiments and did obtain evidence for sexual dimorphism of hepatic peroxisomes.Throughout the experiments we used the liver from both male and female Wistar rats. The conditions of the rats were as follows. Three ∽ five month old sexually mature rats of both sexes. Two ∽ three week old sexually immature rats of both sexes. Rats of both sexes that were gonadectomized and ovariectomized at age 23 days and killed two months later. Some of these gonadectomized rats were killed 7 months later.
Cytofunctional analysis of conveyer system in glandular cells relating to chemical composition of secretion product
Authors: Zufahov K.A. 
Published: June 2020

Since Hirsch /1963/ has described the intracellular conveyer ha protein-secreting cells the oiological science was enriched by many new findings.Comparative studies of synthetic and secretion processes both in endocrine and exocrine glands undertaken in our laboratory have demonstrated that a conveyer system is also preserved in cells secreting non-protein product.The obtained data have shown that there may oe following conveyer systems relating to chemical composition of secretion product: 1.intracellular conveyer of protein-secreting cells; 2.mucus-secreting cells; 3.lipoid /steroid/secreting cells; 4.mineral product /H+-ions,Na+,K+-salts/secreting cells.Using methods of differential centrifugation for the isolation of subcellular structures comprising synthetic conveyer in glandular cells we have found that protein being synthesized initially in the rough endoplasmic reticulum and transported to the Golgi underwent not only simple condensation process but also essential qualitative alterations /Fig.1/.As a rule,this is accompanied by the splitting off additional amino-acid residue from a peptide molecule,that is,the conversion of prohormone into active hormone.
An ultrastructural method for the study of cell viability using ruthenium red
Authors: Féridoun Babaï 
Published: June 2020

Ruthenium Red (RR), a colored inorganic dye, has been used in electron microscopy to stain and visualize the glycoproteins of the cell coat. It has an average particle size of 1.13 nm and does not seem to penetrate the intact plasma membrane. Consequently the cytoplasmic and nuclear components of viable cells are not stained with this electron-opaque marker.We have used these properties of RR to develop a method for the study of abnormal permeability of damaged cell membrane and to stain nonviable cells. Under certain conditions, RR stains the cytoplasm of damaged cells in suspension (Figs. 1,2) or in culture in situ (Figs. 3-5). The stained (permeable) cells are easily visualized under the light and electron microscope.Cell suspension of an ascitic Novikoff Hepatoma and cell culture from a Rhabdomyosarcoma were utilized for this study.
Electron microscopic cytochemistry of functional groups in the lumenal plasma membrane of the rabbit urinary bladder
Authors: Seguchi H. , Okada T. , Ogawa K. 
Published: June 2020

In order to fill gap between the morphological findings and the biochemical ones on the plasma membrane, it is of great value to demonstrate the macromolecular structure ultracytochemically in the plasma membrane. In the present investigation the routine morphological studies, the freeze-etching procedure, the negative staining, the ultracytochemical demonstration of sulfhydryl (SH) groups and the performic acid (PF)-phosphotungstic acid (PTA) reaction (PFP reaction) were performed on intact or isolated lumenal plasma membranes of the rabbit urinary bladder.Glutaraldehyde-fixed intact or isolated lumenal plasma membranes were used. To prepare the isolated lumenal plasma membrane, bladders were excised and distended for 10 min with 0. 02 M sodium thioglycollate, pH 7. 4, at 4°C after washing with 0. 01M HEPES buffer, pH 7. 4. The pooled solution from bladders was centrifuged at 3, 000 xg for 10 min.
Organization of tight junctions in the choroid plexus epithelium
Authors: Van Deurs B. , Koehler J. K. 
Published: June 2020

The choroid plexus epithelium constitutes a blood-cerebrospinal fluid (CSF) barrier, and is involved in regulation of the special composition of the CSF. The epithelium is provided with an ouabain-sensitive Na/K-pump located at the apical surface, actively pumping ions into the CSF. The choroid plexus epithelium has been described as “leaky” with a low transepithelial resistance, and a passive transepithelial flux following a paracellular route (intercellular spaces and cell junctions) also takes place. The present report describes the structural basis for these “barrier” properties of the choroid plexus epithelium as revealed by freeze fracture.Choroid plexus from the lateral, third and fourth ventricles of rats were used. The tissue was fixed in glutaraldehyde and stored in 30% glycerol. Freezing was performed either in liquid nitrogen-cooled Freon 22, or directly in a mixture of liquid and solid nitrogen prepared in a special vacuum chamber. The latter method was always used, and considered necessary, when preparations of complementary (double) replicas were made.
Oncornavirus assembly at the cell surface revealed in replicas of freeze-dried cells
Authors: Demsey Anthony , Stackpole Christopher W. 
Published: June 2020

The murine leukemia viruses are type-C oncornaviruses, and their release from the host cell involves a “budding” process in which the newly-forming, RNA-containing virus core becomes enveloped by modified cell surface membrane. Previous studies revealed that the released virions possess a dense array of 10 nm globular projections (“knobs”) on this envelope surface, and that these knobs contain a 70, 000 MW glycoprotein (gp70) of viral origin. Taking advantage of this distinctive structural formation, we have developed a procedure for freeze-drying and replication of intact cells which reveals surface detail superior to other surface replica techniques, and sufficient to detect even early stages of virus budding by localized aggregation of these knobs on the cell surface.Briefly, cells growing in monolayer are seeded onto round glass coverslips 10-12 mm in diameter. After a period of growth, cells are fixed in situ for one hour, usually with 1% OsO4 in 0. 1 M cacodylate buffer, and rinsed in distilled water.