bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Platinum-Carbon Shadow Width Increase as a Function of Rnown Particle Size on Non-Planar Surfaces
Authors: Ruben G. C. , Telford J. N. 
Published: June 2020

Internal fracture faces of membranes show platinum/carbon (pt/c) shadowed particles averaging in size from 80 to 200 Å. Only two of these internal membrane particles have been identified. Since the shadowed particles often reside on non-planar surfaces of the membrane fracture face, it would be very useful if the increased particle width due to shadowing could be calibrated as a function of real particle width.A test specimen was made in the following manner. Indirectly evaporated carbon films of 40 Å thickness were produced on freshly cleaved mica. The indirectly evaporated carbon film was then mounted on 300 mesh grids. Following this procedure, a heterogeneous sized population of gold particles was deposited on the film surface by evaporating gold very slowly in 900 mm of Helium. The 300 size mesh grids were selected in order that the carbon film would sag in the middle thereby providing a variety of angles relative to the source of shadowing.
Giant Mitochondria in Hepatocytes Following Concanavalin A Administration
Authors: Nopanitaya Waykin , Tyan Marvin L. 
Published: June 2020

Concanavalin A (Con A), a protein obtained from the jack bean, has been used intensively in vitro in a topographical study of the structure of cell plasma membrane. In vivo toxicity following a single dose of intravenous injection of Con A has been recently noted in the mouse during an investigation of the immunosuppressive properties of this known phytohaemagglutinin. In that preliminary report, histopathological changes in various organs including the liver were described by light microscopy. Ultrastructural changes in hepatocytes caused by Con A have not been described. Presented here are observations on the ultrastructural alterations in hepatocytes and their mitochondria following a single dose of intravenous injection of this toxic lectin.Concanavalin A in a balanced salt solution (800 μg Con A in 0.2 ml) was individually given intravenously to adult male B6D2F1 mice. Groups of mice were sacrificed by cervical dislocation 1, 2, 7, 14, and 28 days after the injection of Con A.
Quantitative Electron Microprobe Studies of Human-Platelet Dense Bodies
Authors: Tanaka Y. , Costa J.L. , Pettigrew K.D. , Yoda Y. , Cushing R.J. 
Published: June 2020

As seen in air-dried whole mounts, human-platelet dense bodies (DB) are discrete, electron-opaque structures ranging in size from approximately 50 nm to 1000 nm in diameter (Fig. 1). We have examined DB elemental composition and peak-to-background (p/bg) ratios using a Hitachi HU-12A microscope in the transmission-scanning mode and a Kevex energy-dispersive X-ray detector and analysis system. Qualitatively, spectra from probed DB showed strong signals for calcium and phosphorous, and a less prominent peak for potassium. No magnesium peak was detected (Fig. 2).Quantitatively, probing 11 randomly-selected DB with a beam spot approximately 10 nm in diameter (75 kv accelerating voltage) gave phosphorous p/bg ratios with a coefficient of variation (CV) of 71.32, calcium p/bg ratios with a CV of 75.34, and elemental phosphorous/calcium (P/Ca) ratios with a CV of 18.10 (Fig. 3). Peak-to-background ratios for both elements demonstrated low correlations with the area of the DB probed (r = 0.12 and 0. 39 for phosphorous and calcium, respectively, based on a sample size of 67 DB's), suggesting that only a small fraction of the total DB area was being sampled.
Propagation of JC Virus in Glia Cells in PML (Progressive Multifocal Leukoencephalopathy
Authors: Preskorn S. , Kepes J. , Bopp W.J. , Watanabe I. 
Published: June 2020

PML, a rare form of subacute demyelinating disease of the human brain, is caused, in most instances, by JC virus, a new type of papova virus. Light microscopically, the lesions are characterized by hypertrophy of oligodendroglia with intranuclear inclusion and gigantic astroglia with bizarreshaped nuclei. Although viral particles have been found by many investigators, the use of autopsy material has limited the ultrastructural study of changes in the patient.This report concerns some new cytopathological changes based on an electron microscopic study of well fixed biopsy material. Oligodendroglia and astroglia were markedly hypertrophic, but were identified by the presence of abundant cytoplasmic microtubules and filaments, respectively. Intranuclear and intracytoplasmic virions were found in both cell types. The intranuclear virions were the typical round and filamentous forms, with diameters of 40 and 30 mμ, respectively. They were scattered randomly throughout the enlarged nuclei.
Fine Structural and Pathologic Evaluation of Moloney Sarcoma Virus (MSV) -Induced Osteosarcoma in the Rat
Authors: Olson H. M. , Capen C. C. 
Published: June 2020

Osteosarcoma, an important neoplastic disease particularly in young male adults, has been produced experimentally in the rat or hamster by bone-seeking radionuclides (90Sr, 45Ca.), extracts of human osteosarcoma, and viruses (MSV) (Ikemoto and Yamamoto, Gann 63:141, 1972 and Soehner and Dmochowski, Nature 244:191, 1969). In our investigations experimental osteosarcomas were produced in neonatal (less than 24 hours old) New Zealand black rats by direct intratibial inoculation of a MSV preparation in citrate buffer and equine serum. The objective of this investigation was to characterize a MSV-induced osteosarcoma model in the neonatal rat by radiographic, light and electron microscopic evaluation.Bone tumors could be detected by palpation as soon as 20 days after virus inoculation. The tumor incidence achieved in inoculated litters has reached 55% (5/9 rats) in our laboratory. Sequential radiographs in rats demonstrated evidence of both osteolytic and osteoproliferative activity in the tumor, with progressive dissolution of tibial cortical bone (Fig. 1).
Electron Microscopy of Wound Healing in Patients with Hernia
Authors: Sun C.N. , White H.J. , Read R.C. 
Published: June 2020

Previously we have reported the defect of collagen fibrils from herniated rectus sheath. This presentation includes additional sections from postsurgical incisions (10 days) from both control and hernia patients. Small pieces of rectus sheath were fixed in 3% glutaraldehyde in phosphate buffer (pH 7.2) and post fixed with buffered 2% osmium tetroxide. The tissues were then dehydrated in serially increasing concentrations of alcohol and embedded in Epon 812. Sections were stained with 2.5% phosphotungstic acid or uranyl acetate and lead citrate.Previously we found that collagen fibrils from "non-herniated" rectus sheath have uniform diameters and 640 Å periodicity with seven or more intraperiodic bands resembling typical native collagen fibrils, while the fibrils from fascia obtained from patients with direct herniation show considerable variation in diameter. These variations are often found in the same individual fibers with a range from 300 Å to 3000 Å.
Fine Structural Features of Neurosarcomas
Authors: Mackay Bruce , Valenzuela Jorge , Butler James J. 
Published: June 2020

In an electron microscopic study of an extensive series of malignant tumors of the soft tissues, sarcomas derived from elements of the peripheral nervous system were observed to possess unique morphologic features. Since these features were not seen in any of the other types of soft tissue sarcoma, they are useful as diagnostic criteria. They also provide insight into the histogenesis of neurosarcomas.By light microscopy, some neurosarcomas are seen to be composed of compactly grouped, spindle-shaped cells, and intercellular connective tissue is scanty. In other neurosarcomas, dendritic or stellate cells are loosely arranged in a relatively clear, occasionally myxoid-like stroma. The two types of tissue frequently coexist in the same neoplasm, and both are common in benign tumors of the peripheral nerves.Figure 1 shows part of a tumor cell from a neurosarcoma of the loosely-textured variety. The cytoplasm extends into a slender branching process containing longitudinally-oriented microtubules and fine filaments.
Tissue Response to Vascular Prosthetic Materials
Authors: Narconis R.J. , Spindler J.W. , Billy L.J. , S. Rana  
Published: June 2020

Tissue response to three types of vascular prosthetic materials was evaluated by correlation of scanning electron microscopy and light microscopy. Two clinically established materials, woven dacron and woven teflon, and an experimental material, expanded polytetrafluoroethylene (Goretex) were employed. They were implanted in the subcutaneous tissue of rats and removed at time intervals ranging from 48 hours to 30 days. Half of the retrieved material was fixed in 10% formalin and examined by routine light microscopy. The other half was glutaraldehyde fixed and acetone/CO2 critical point dried, then examined by scanning electron microscopy.Prior to this study, the three materials were evaluated by scanning electron microscopy to establish topographic landmarks. The woven dacron had bundles of relatively large, rough fibers; the woven teflon had fibers of similar size but with a smooth surface; the PTFE, however, had a surface composed of fibers and pores only a few micra in diameter.
Scanning Electron Microscopy of Carcinoma and Precancerous Lesions of the Colon
Authors: Siew S. 
Published: June 2020

In this investigation, fresh operative resected specimens showing carcinoma of the colon and presumed precancerous lesions, such as, adenomatous polypi, were examined by means of scanning electron microscopy. In addition, a study was made of small (2-3 mm) discrete nodules which were observed in apparently unaffected mucosa in such cases.Scanning electron microscopy of normal colonic mucosa shows an even, undulating pattern, punctuated at regular intervals by the invaginations of the crypts. The crypt openings are surrounded by slightly raised clusters of cells. The cellular configuration is fairly uniform with regard to the size, shape and polarity of the cells. The luminal surface is serrated owing to the presence of microvilli which form fine regular projections over the whole border of the intact cell. (Fig. 1)The small discrete nodules show an uneven mammilated surface which is divided by deep clefts into unequal lobules.
Ultrastructural Changes in Dog Thyroid Follicular Cells Induced by Chronic Thyrotropin Administration
Authors: Fernandez-Pol J. A. , Hays M. T. 
Published: June 2020

The acute ultrastructural effects of Thyroid Stimulating Hormone (TSH) in vivo or in vitro are well documented. However, little is known about chronic effects of TSH administration. The purpose of the present study was to define the ultrastructural changes induced by chronic TSH administration.Ten Mongrel dogs weighing between 18-20 kg were used in these studies. They were divided in two groups:Control group: (4 dogs) These dogs were administered saline solution, (0.09% NaCl) intramuscular for 10 days.TSH treated group: (6 dogs) These dogs received a daily intramuscular
injection of TSH, 15 IU for 10 days.All dogs received 300 mg of Thyroid extract per day for 3 days prior to the operation. Then, they were thyroidectomized on the 11th day. Immediately after removal of the thyroid gland, tissues were fixed in glutaraldehyde 37, in phosphate buffer at pH 7.4 for 2 hrs.
Cytochemical Localization of Acid Phosphatase in WI-38 Cells Observed by HighVoltage Electron Microscopy
Authors: Wolosewick John J. , Porter Keith R. 
Published: June 2020

One of the major problems in the interpretation of high voltage electron micrographs of whole cultured cells results from the superimposition of membranes, filaments, ribosomes, etc., in the final 2-dimensional image. The gains provided by the greater penetrability and resolution of the higher energy beam are to some extent lost in the confusion introduced by the overlap of structures. The problem is overcome in part by stereomicroscopy and this becomes the routine procedure for thick specimens. The effectiveness of this is greatly improved, however, if the object or organelle of special interest can be selectively stained. Toward this end we have explored the use of cytochemical techniques which identify the distribution of certain intracellular enzymes. The results will be illustrated with procedures for acid phosphatase.The “aging” human diploid cell line WI-38 (passages 25-30) was cultured on sterilized, formvar-coated gold grids lightly shadowed with carbon. The cells were fixed for 1 hr. at 0-4°C in 2% glutaraldehyde in 0.1M sodium cacodylate (pH 7.2) plus 0.1M sucrose.
Na+K+ Dependent Atpase as a Specific Marker for Myoepithelial Cells: An Ultrastructural Study.
Authors: Russo J. , Wells P. 
Published: June 2020

One of the problems in the study of mammary carcinomas is the cellular heterogeneity which they present. The use of a specific histochemical marker can help to distinguish the two principal cellular types found in the mammary gland; the epithelial and myoepithelial cells.Mammary glands of female Balb/C mice of different ages were removed and fixed in 1.5% glutaraldehyde in 0.1M cacodylate buffer pH 7.2 with 1% sucrose. After two hours of fixation at 4°C, the material was washed in 0.1M cacodylate buffer, sectioned with a Smith-Farquar microtome set at 70-100u, and incubated for the histochemical detection of ATPases. The tissue was then washed again with 0.1M cacodylate buffer, postfixed in 1% osmium tetroxide, dehydrated, and embedded in an Epon-Araldite mixture.For the Mg++ dependent ATPase the conventional method of Wachstein and Meisel was followed. The Mg++ dependent ATPase is localized in the plasma membranes of the epithelial and myoepithelial cells (Fig. 1).
Scanning Electron Microscopy of the Taste Bud of the Mudpuppy, Necturus Maculosus
Authors: Samanen David W. , Bernard Rudy A. 
Published: June 2020

The tongue of the mudpuppy, Necturus maculosus, appears smooth and without any papillae. Farbman and Yonkers (1971) reported that the tongue contains round elevations or eminences, each with a single, large taste bud. Furthermore, their light micrographs, made of sectioned tissue, showed that the tips of the buds are flush to the lingual surface. In contrast, the mammalian taste buds lie below the epithelium of the lingual papillae and contact the surface only by way of a narrow taste pore. We undertook SEM studies to confirm this morphology, one which would be advantageous for later neurophysiological studies involving the stimulation of individual taste buds and microelectrode recording from taste bud cells.Figure 1 shows two adjacent eminences from the mudpuppy's distal tongue. The taste bud shows as a surface irregularity, centered at the top of each mound. Their dimensions and general distribution correspond to those reported by Farbman and Yonkers.
Optical Diffraction Of The Z Lattice In Striated Muscle
Authors: Goldstein Margaret A. , Schroeter John P. , Sass Ronald L. 
Published: June 2020

Each normal striated muscle fiber has a characteristic Z width at rest length. Previous EM studies of thin Z bands in skeletal muscles have led to a variety of three dimensional models. Recent observations based on thicker Z bands have been incorporated into one of these models. As a first step in understanding three dimensional aspects of the Z band we have constructed a model lattice based on observations of cross sections. We are testing the assumption that regardless of the thickness of the Z band at rest length as observed in longitudinal section, the lattice unit cells as viewed in cross section will be simply related.Viewing the Z band as a crystalline lattice suitable for analysis by optical diffraction techniques, we are studying a variety of striated muscles in different physiological and pathological states. Muscles are fixed in paraformaldehyde glutaraldehyde and postfixed in osmium tetroxide.
Ultrastructural Changes in the Root Meristem Cells of Rubus Chamaemorus L. (Cloudberry)
Authors: Bal Arya K. 
Published: June 2020

In the course of studies in the root meristem tissue of Rubus chamaemorus L. some important changes in the ultrastructural morphology were observed during the initiation of senescence at the end of the growing season.Root meristems were collected from naturally growing healthy populations of Cloudberry plants, and fixed in Karnovsky's mixture or in 2.5% glutaraldehyde in phosphate buffer. The samples were osmicated, dehydrated following usual methods and embedded in Epon. Ultrathin sections were stained in uranyl acetate and lead citrate.Figure 1 shows part of a dense cell in the meristem. The electron density of these cells is due to large amounts of a particulate material in the cytoplasmic matrix. The smallest particle seen in electron micrographs is about 40 A, although larger aggregates are also found, which remain randomly distributed in association with various cell organelles. Dense substance has been found associated with golgi membranes, proplastids, vacuoles and microtubules (Fig. 2).
Scanning Electron Miscroscopy of Marsilea Sperm
Authors: Shih C. Y. 
Published: June 2020

Although spermatogenesis in Marsilea has been studied initially by Sharp with the light microscope (LM), and subsequently by Mizukami and Gall with the transmission electron microscope (TEM), the overall organization of the sperm has not been recorded in detail with photomicrograph. The small size of the sperm (about 16 micrometers in diameter) makes it difficult to resolve the fine detail with the IM and the specimens are too thick to derive useful information by studying whole mount preparations with the TEM. The SEM with a magnification and resolution range which is intermediate between the LM and TEM can be useful to characterize the organization and surface detail of the Marsilea sperm.Marsilea is a water fern which has the appearance of a four leaf clover. The sporangia are enclosed within a hard, rounded sporocarp which is located at the base of the leaf. Germination of the mature sporocarp can be hastened in the laboratory by excising a small piece of the wall and immersing the sporocarp in water.
An Electron Microscopy Study of the Glycocalyx of Isolated Germinal Cells of the Rat
Authors: Hernández-Jáuregui P. , Trejo-Bayona R. , Delhumeau-Ongay G. 
Published: June 2020

The surface coat or glycocalyx of animal and plant cells plays an important role in cell properties such as antigenicity, specific permeability, and ATP ase activity. In the spermatozoa the glycocalyx may be of great importance in capacitation and fertilization phenomena. The glycocalyx is rich in fucose, mannose, galactose and sialic acid. These components are diminished during cell division. During spermatogenesis in mammals, spermatocytes represent a long prophase of meiosis. The purpose of this work was to demostrate the possible variations in the amount of glycocalyx in isolated germinal cells during spermatogenesis differentiation.Rat testes from 10, 23, and 38 days old, were finely scissored, in presence of Eagle essential medium, (mechanical treatment) Another similar group of isolated cells was treated with colagenase. (chemical treatment). Once separation of cells was completed, samples were treated for cytochemical electron microscopy using Alcian blue-lanthanum nitrate as previously described.
Characterization of Chemical Impurities in Glutaraldehyde
Authors: Grenon B. J. , Tousimis A. J. 
Published: June 2020

Ever since the introduction of glutaraldehyde as a fixative in electron microscopy of biological specimens, the identification of impurities and consequently their effects on biologic ultrastructure have been under investigation. Several reports postulate that the impurities of glutaraldehyde, used as a fixative, are glutaric acid, glutaraldehyde polymer, acrolein and glutaraldoxime.Analysis of commercially available biological or technical grade glutaraldehyde revealed two major impurity components, none of which has been reported. The first compound is a colorless, water-soluble liquid with a boiling point of 42°C at 16 mm. Utilizing Nuclear Magnetic Resonance (NMR) spectroscopic analysis, this compound has been identified to be — dihydro-2-ethoxy 2H-pyran. This impurity component of the glutaraldehyde biological or technical grades has an UV absorption peak at 235nm. The second compound is a white amorphous solid which is insoluble in water and has a melting point of 80-82°C. Initial chemical analysis indicates that this compound is an aldol condensation product(s) of glutaraldehyde.
Screening Electron Microscopy Sections with PolanretTM Light Microscope
Authors: Turner J. N. , Lillibridge C. B. , Meltzer R. J. , Park E. D. 
Published: June 2020

A new, variable phase contrast microscope, the PolanretTM, has been developed which is particularly suited to the optical screening of thin sections for electron microscopy with regard to tissue orientation and section quality.By preliminary examination, defects in preparation of the specimen can be discovered immediately after sectioning and prior to staining or examination with the electron microscope. Such examination of unprocessed sections which are thinner than conventional light microscopy sections is possible because the Polanret TM system can make exceptionally small differences in optical path. Using the PolanretTM microscope, the phase and amplitude can be adjusted continuously so as to achieve optimum specimen contrast. The microscope can thus be used to visualize specimen defects and intracellular details in a way which conventional phase microscopy is unable to do.This preliminary screening technique was evaluated for its usefulness in detecting microtome knife defects, i.e., scratches and chatter, so that corrective measures could be taken.
Enzyme Digestion of Epon Embedded Akinetic Cilia
Authors: Hess R. A. , Thurston R. J. , Kilburn K. H. 
Published: June 2020

Terminal gill cilia of the freshwater mussel Unio stop beating when exposed to hyperosmolar solutions. Ultrastructural studies of the cilia during akinesia showed the absence of the 9+2 doublet microtubules and the ciliary matrix was amorphous and extremely electron dense (Fig. 2). It seemed possible that the axonemal microtubules might not be disrupted by shock-stopping cilia, but rather were obscured by the formation of the pleomorphic matrices. This hypothesis was tested using a modified enzymatic proceedure which has been shown to specifically digest spermatozoa flagellar microtubules in Epon ultrathin sections.Terminal gill filaments with control cilia beating in aged tap water and akinetic cilia which had been exposed to 0.154 M NaCl were fixed at 22°C for 30 min in 3% phosphate buffered (pH 7.35) glutaraldehyde and post-fixed at 22°C for 30 min in 2% buffered osmium tetroxide. The gills were rinsed in buffer, dehydrated in ethanol and embedded in Epon 812.
Characterization of Rapidly Solidified Aluminum-Lithium Alloys
Authors: Gayle Frank W. , VanderSande John B. 
Published: June 2020

Aluminum-lithium alloys are presently the subject of much research due to the effectiveness of lithium in reducing density, raising elastic modulus and providing for high strength. The strengthening precipitate is the metastable, L12-ordered Al3Li (Cu3Au prototype), or δ'. In binary alloys, δ’ precipitates homogeneously with a spherical shape, coherent with the aluminum matrix. These lithium-containing alloys suffer from poor ductility and fracture toughness, however, which has been attributed to 1) the shear-able nature of the δ’ precipitate, resulting in work softening and slip localization on the relevant slip planes, and 2) precipitate free zone formation along high angle grain boundaries.In a previous paper we proposed that Zr could partially substitute for Li in δ', resulting in a ternary Al3(Li,Zr) phase, which we call δ”. It was anticipated that such a phase would be more resistant to dislocation shear than δ’ from observation of deformation behavior of Al-Zr alloys containing the coherent L12-ordered Al3Zr precipitate.