bluuebunny/crossref_metadata_2025_split huggingface dataset:
The tendon — a homeostatic unit tuned to mechanical forces
Authors: Merrilees M. J. , Gillard G. C. , Flint M. H. 
Published: June 2020

To determine the role of mechanical forces in the maintenance and control of cell and matrix organization of connective tissues, we have undertaken a morphological and biochemical study of the rabbit hind limb Flexor Digitorum Profundus (FDP), a single tissue which is subjected to both tensional and compressive forces during normal function. Like all tendons, the FDP is designed to transmit tensional forces, but as it passes below the ankle a segment in contact with the calcaneum and talus is subjected to additional compressive forces. In this region the anterior half of the tendon is thickened to form a lenticular shaped sesamoid-type pad (Fig. 1) where cell and matrix organization resembles fibro-cartilage.The tensional regions of the FDP are characterized by elongated, flanged fibroblastictype cells intimately surrounded by densely packed, positively charged, collagen fibrils of long periodicity (63 nm) (Figs. 2 & 3), and small amounts of proteoglycan (0. 15% dry wt. ), predominantly dermatan sulphate.
Microanalysis in mitochondrial granules of bone cells incident to experimental tooth movement
Authors: Hirashita A. , Nakamura Y. , Okumura E. , Kuwabara Y. 
Published: June 2020

Biological functions of Ca in mitochondrial granules have been reported by a number of investigators. It is said that mitochondrial granules of chondrocytes, osteoblasts and osteocytes in rat epiphyseal growth plate with regard to bone calcification and these granules of osteoclasts at bone-resorbing site play an important role of Ca-transport. However, these results were reported about the first stage of calcification in rat epiphyseal growth plate, so that the changes of bone tissues in adult rats seem to be not always the same.The purpose of this work is, by electron probe X-ray microanalysis method, to do the elemental analysis in mitochondrial granules of osteoblasts, osteocytes and osteoclasts incident to experimental tooth movement in adult rats, and to compare them with these analysis in control groups.
Energy dispersive microprobe analysis of intracellular mineral deposits in rat bone
Authors: Dempster D.W. , Nicholson W.A.P. , Elder H.Y. , Smith D.A.S. , Ferrier R.P. 
Published: June 2020

The use of an energy dispersive X-ray microanalytical system (EDX) attached to a conventional transmission electron microscope (TEM) allows images of good morphological resolution from ultra-thin specimens and spectra of all detectable elements to be obtained simultaneously at radiation doses which are low compared to wavelength dispersive detectors. For reasons of detection efficiency the solid angle subtended from the specimen to the detector is maximised (∼0.l sterad) in our system, a LINK SYSTEMS 290 with a 30mm2Si(Li) crystal fitted to a JEOL JEM lOOC. However, with this type of system the recorded spectrum has contributions not only from the small areas which can be probed but also from scattered electrons, and X-rays originating in the surrounding specimen, the specimen support system and the microscope environment of the specimen. The problem is particularly acute in projects, such as the present, where it is necessary to detect and determine the ratios of elements (Ca and P) in small quantities in close proximity to relatively massive concentrations of the same elements.Modifications to our system have been described (Nicholson et al., 1977a;Biddlecombe et al., 1977) which greatly improve the peak/background ratios for quantitative analysis and eliminate all of the specific peaks of non-specimen origin. For ease of maintenance the JEOL 100C is fitted with thin foil condenser apertures (10μm thick molybdenum) as standard. At the accelerating voltage used in this study (80 keV) a considerable number of electrons are transmitted by these apertures and with the electron probe placed adjacent to fully mineralized bone the scattered electrons were responsible for generation of sizeable Ca and P signals. We have replaced the standard foils with thick (0.25 mm) molybdenum apertures.
Ultrastructural studies of cartilage in genetic disorders of skeletal growth
Authors: Sillence D. O. , Rimoin D. L. , Silberberg Ruth 
Published: June 2020

The human skeletal dysplasias are an heterogeneous group of heritable connective tissue disorders associated with abnormalities in the size and shape of the limbs, trunk and/or skull which frequently result in disproportionate short stature. In recent years it has become apparent that these comprise over 50 distinct conditions with a variety of subtypes distinguished on clinical and radiological grounds. We have investigated the pathogenesis of these conditions in over 100 patients by direct transmission electron microscopic examination of chondro-osseous tissue. Some of the ultrastructural studies have been previously reported.Small biopsies of chondro-osseous junction were collected for electron microscopy from the rib or iliac crest of patients with skeletal dysplasias or from normal controls at the time of surgery. These were cut into small blocks and fixed for one hour in either 5% glutaraldehyde in white's buffer or directly in 1% osmic acid in White's buffer or a modified Karnovsky's fixative, (2. 5% paraformaldehyde, 2. 5% glutaraldehyde, 2. 5mM calcium in cacodylate buffer). Subsequent processing included osmium fixation, block staining with uranyl acetate and embedding in Araldite or Spurr's low viscosity resin (firm composition). Sections were cut with glass knives or diamond knives. The latter produced sections which were much more even in thickness, permitting more consistent appraisal of matrix features.
Bone tissue response to dense hydroxylapatite disc implants in mongrel dogs: a light and electron microscopic study
Authors: Jasty V. , Jarcho M. , Gumaer K. I. , Sauerschell R. , Drobeck H. P. 
Published: June 2020

Ceramics have distinct advantages over many other materials for use as implantable prosthetic devices. As implant materials, they are virtually nonreactive, and unlike many metals they are corrosion resistant. When properly formulated and fabricated, their compressive and tensile strengths would be appropriate for use as prosthetic devices. A new process for preparing a dense polycrystalline hydroxylapatite (HA) ceramic called durapatite has been formulated. This material appears particularly attractive as a candidate for hard tissue implant because of its strength and because its chemical composition closely resembles that of vertebrate bone and tooth minerals.Durapatite in the form of dense plugs was surgically implanted into drilled holes in the femurs of four adult mongrel dogs. Two dogs were sacrificed two months postimplantation and two at approximately seven months.
High-pressure freezing and freeze-fracture replication of starch gels for high-resolution TEM
Authors: Basgall E. J. , Day G. A. 
Published: June 2020

Gelled food products with a high water content (∼80%) must be vacuum stabilized for electron microscopic studies of their ultrastructure. Conventional chemical fixation techniques produce unacceptable artifacts when applied to many gel or emulsion type samples. Rapid freezing is necessary in order to stabilize the matrix without appreciable ice crystal formation. High pressure freezing has been shown to produce vitrification of thick samples (up to .5 mm).Freeze-fracture/etch surface replication and TEM has been used successfully to visualize the spatial structure of aqueous carboxymethyl cellulose gels after ultra rapid freezing/Cryo-SEM has, been used to study starch gel and food emulsion structure directly. Cryo-SEM is generally limited in resolution and does not provide structural details in the 10-20 angstrom range. High pressure freezing and freeze-fracture replication is the preferred method for immobilizing and studying ultrastructural details at high resolution.
Ice damage resulting from crystallization of bound water in freeze-dried cells
Authors: Wray G. P. , Grant K. W. , Lewis J. C. 
Published: June 2020

Rapid freezing followed by freeze-drying is widely used as a strategy to preserve the 3-dimensional architecture of cells and tissues. This combination of methodologies is proving invaluable as a complementary approach to chemical fixation and critical point drying in studies which are concerned with subtle arrangements of the cytoplasmic matrix. As with other preparative techniques, freeze-drying raises questions, one of which is the degree of dehydration obtained during the drying process. We present data here that under conditions typically used for freeze-drying, sublimation of cell water is incomplete, and this residual water alters cytoarchitecture during the post-dry warming phase.Human blood platelets, obtained from healthy donors following informed consent, were separated from anticoagulated (1 part 3.8% sodium citrate to 9 parts blood) blood and washed in balanced salts to remove plasma proteins. The cells were then adhered for 30 minutes at 37°C to carbon-stabilized formvar-coated, gold grids, and then rapidly frozen with a modified Gentleman Jim apparatus by plunging into liquid N2 cooled propane. The frozen cells were then transferred to a custom built freeze-drying module which was mounted on a Denton DV-502 vacuum system.
Electron Microscopic observations of channel catfish macrophages infected with Edwardsiella ictaluri
Authors: Stanley L. A. 
Published: June 2020

Edwardsiella ictaluri, a gram negative rod shaped enteric bacterium, is the etiological agent of Enteric Septicemia of Catfish (ESC). Little is known about the pathogenic mechanisms operative in ESC. It has been reported that infected macrophages are apparently unable to destroy the bacterium. The objective of this study was to detect differences in the way E. ictaluri virulent and avirulent strains associate with and are engulfed by channel catfish macrophages. This should help to characterize the possible role macrophages play in the disease process of ESC.The virulent bacterial strains used in this study were isolated from the kidneys of moribund channel catfish. Attenuated avirulent forms were derived from virulent strains by subsequent passages on Brain Heart Infusion Agar. The virulent and avirulent types were metabolically identical. Channel catfish, Ictalurus punctatus, were used as the susceptible host animals for experiments. For phagocytic studies, channel catfish macrophage suspensions were prepared as described by Trust et al.
ESI detection of titanium in lungs of a spray paint sniffer
Authors: Tryka A. F. , Cox W. E. , Van Devanter S. H. 
Published: June 2020

Do lungs of inhalation substance abusers contain materials indicative of such abuse, and is it possible to detect these materials by electron energy loss spectroscopy? While most abuse involves only volatile materials, spray paint is one material where when volatile materials evaporate, resultant solid particles may be of respirable size. These particles may contain paint pigments such as titanium dioxide.Lung biopsy tissue was obtained for diagnostic purposes from a 16 year old male who presented with acute onset of progressive respiratory insufficiency. The patient later admitted to a history of significant paint sniffing. Desquamative interstitial pneumonitis was observed by light microscopy, with an unusual additional feature of many alveolar macrophages having dusty cytoplasm. Routine ultrastructural study demonstrated large amounts of electron dense material in these macrophages. To address the question of what materials were present in the cells, additional tissue samples were embedded in Araldite, sectioned at 30 nm, and viewed unstained on a Zeiss 902.
Ultrastructural characterization of primary cultures of liver cells obtained from the Japanese medaka, Oryzias latipe
Authors: Norton W. , Garrett L. , Finch R. , Gardner H. 
Published: June 2020

Nonmammalian models for investigations involving carcinogenesis have been developed as complementary extensions of current mammalian testing systems. Several species of fish, including Japanese medaka Oryzias latipes have proven to be very effective and reliable models for carcinogenesis studies, the majority of which have concentrated on hepatocellular carcinogens.The primary objective of this investigation was to provide basic ultrastructural information regarding cultured liver cells of medaka which would be beneficial in subsequent experiments relating to the utilization of cell cultures in carcinogenesis studies. Primary cultures of cells from livers of 20 adult medaka were obtained by trypsinization of fragmented organs. Initial cell viability, as monitored by trypan blue exclusion, was determined to be greater than 95%. Cells were plated in a complete medium composed of Dulbecco's MEM supplemented with 10% fetal calf serum, 25mM HEPES buffer, 1% sodium pyruvate, 1% non-essential amino acids and antibodies. Cell density of 5.0 to 7.5x105 cells/ml was optimal.
Abnormal spermiogenesis in hybrid mice (C57BL X C3H)F1 treated with the mutagen ethyl methane sulphonate
Authors: Gallegos M.G. , Ramírez E. , González D.J. 
Published: June 2020

Ethyl methane sulphonate is an agent that produces a notable elevation in the percentage of morphologically abnormal spermatozooids. Inducement of minimal defects of the hook, bicephalic, biflagellated and amorphous forms and filamentous spermatozzoids have been described. The cytotoxic effect of the drug is manifested by death of primary spermatocytes, which is associated to the low number of epididlmary spermatozooids. The mechanisms that produce teratospermia have not been previously studied exhaustively.Hybrid mice of genotype (C57BL X C3H)F1 of 8 to 12 weeks of age were treated intraperitoneal ly with EMS at a dose of 200 mg/Kg for five consecutive days and killed four weeks later by cervical dislocation. The testicular tissue was fixed by inmersion in 6.5% glutaraldehyde in 0.2 M phosphate buffered saline at pH 7.3 and 4°C, and was included in epoxyresine. Fine sections were stained in leal citrate and uranyl acetate, and were observed in Zeiss EM109 electron microscope.
Ultrastructure of developing visual cortical synapses in the cat superior colliculus
Authors: Miller Caroline A. , Bruce Laura L. 
Published: June 2020

The first visual cortical axons arrive in the cat superior colliculus by the time of birth. Adultlike receptive fields develop slowly over several weeks following birth. The developing cortical axons go through a sequence of changes before acquiring their adultlike morphology and function. To determine how these axons interact with neurons in the colliculus, cortico-collicular axons were labeled with biocytin (an anterograde neuronal tracer) and studied with electron microscopy.Deeply anesthetized animals received 200-500 nl injections of biocytin (Sigma; 5% in phosphate buffer) in the lateral suprasylvian visual cortical area. After a 24 hr survival time, the animals were deeply anesthetized and perfused with 0.9% phosphate buffered saline followed by fixation with a solution of 1.25% glutaraldehyde and 1.0% paraformaldehyde in 0.1M phosphate buffer. The brain was sectioned transversely on a vibratome at 50 μm. The tissue was processed immediately to visualize the biocytin.
The guard mother cell dormancy of soybean cotyledon
Authors: Chou T. C. , Liu K. C. 
Published: June 2020

The cotyledons of soybean seeds serve both as a food source and a photosynthetic organs for the early development of soybean seedlings. The development of the stomata of cotyledons should be important and related to the food source utilization and the mechanism of photosynthesis. During the study of the development of the cotyledon stomata of soybean seeds, a phenomenon was observed on the upper epidermal layer of the cotyledon, we call it. “the dormancy of the guard mother cell”, which is not reported in the literature available to us.Soybean seeds were soaked, planted and sampled at 24, 48, and 72 hours after planting. The upper epidermal layers were stripped with a sharp razor blade, and processed for observation with Hitachi S-2300 scanning electron microscope.
An SEM study of the structure and classification of the leaf trichomes in the genusLycopersicon(tomato)
Authors: Gillott M. A. , Masiunas J. 
Published: June 2020

Species of the genusLycopersiconcharacteristically possess pubescent leaves; seven types of trichomes were described in 1943, based on light microscopic observations. Recently, there has been renewed interest in trichomes since the presence and density of certain types of trichomes has been related to insect resistance in some species and/or varieties of tomato.Trichomes can be divided into two functional categories, depending on whether the tips are pointed or glandular. Within each of these categories, trichome types have been further differentiated according to the length and number of cells in the stalk and the complexity of the basal structure. Three non-glandular and four glandular types have been described inLycopersicon.Our SEM observations of tomato leaf surfaces suggest that there may be a need to re-evaluate Luckwill's classification of trichome types.
Rotation of small fluorophores in cell cytoplasm measured by confocal anisotropy imaging and picosecond microfluorimetry
Authors: Verkman A.S. , Dix J.A. , Armijo M. , Fushimi K. 
Published: June 2020

The Theological properties of cell cytoplasm are of importance for a number of intracellular processes including diffusion-limited enzyme reactions, intracellular vesicle trafficking, solute transport and cell motility. A wide range of cytoplasmic viscosities have been reported from fluorescence anisotropy, photobleaching recovery, tracer diffusion and electron spin resonance methods. To examine the viscosity of the fluid space between macromolecules and cytoskeletal structures in intact cells, the time-resolved picosecond motion of small fluorophores was measured. Unlike previous methods, measurements of time-resolved fluorophore motion are not confounded by probe binding to and restriction by intracellular structures.Picosecond anisotropy decay was measured by multi-harmonic phase modulation microfluorimetry. The excitation source was a 9 watt argon laser which was impulse modulated by a Pockel's cell. Light was polarized and focused onto a < 1 μ spot on a fluorescently labelled cell. Emitted light was filtered and detected by a phase sensitive photomultiplier through a rotatable analyzing polarizer. Thirty to forty pairs of differential modulation amplitudes and phase angles were collected in parallel over the frequency range 5 to 250 MHz.
Characterization of endocytosis in intact cells by quantitative fluorescence microscopy
Authors: Maxfield Frederick R. 
Published: June 2020

Endocytosis, the process by which extracellular macromolecules are taken into the cell is particularly amenable to quantitative analysis using fluorescence techniques. Fluorescently-labeled proteins and other macromolecules are taken up by cells via receptor-mediated endocytosis or fluid phase pinocytosis. Recently, fluorescent lipid probes have also been synthesized which label the endocytic pathway, allowing observation of lipid membrane traffic.Digital imaging allows the manipulation of images, background and autofluorescence subtractions, and fluorescence intensity measurements of individual endocytic compartments. Image intensification microscopy and digital image processing have been used extensively for studies of endocytosis, including the measurements of endosome pH, and the identification and quantitation of endocytic vesicle fusion. Recently, pathways taken by endocytosed fluorescent molecules have been followed using the confocal microscope, adding a powerful tool to investigate questions about endocytosis which were very difficult to study with conventional, full-field microscopy techniques.
A combined pre- and post-embedding double labeling in the central nervous system with good tissue preservation
Authors: Milroy A.M. , Ralston D.D. 
Published: June 2020

Multiple labeling at the electron microscopic level is routinely done in various parts of the central nervous system. We demonstrate that the pre-embedding tetramethylbenzidine (TMB) reaction for visualizing horseradish peroxidase (HRP) of Olucha and the slow osmication of Henry combined with a post-embedding nonetching immunogold method will also preserve good ultrastructure. Furthermore, the post-embedding immunocytochemistry of some neurotransmitters, i.e. gammaaminobutyric acid (GABA), can be done months after the tissue has been reacted for HRP and embedded in regular epon.Pre-embedding histochemistry:The use of TMB as a chromagen for the demonstration of neuronally transported HRP has both the advantage of being highly sensitive and of producing very specific needle-like crystals. Olucha et al demonstrated that one could further stabilize this reaction product with amonium heptamolybdate. Unfortunately the next step, fixation with regular osmium tetroxide, often resulted in the loss of the reaction product. However, the slow osmication with a lower pH (5.5) in the phosphate buffer at room temperature as recommended by Henry et al prevented this loss, and at the same time resulted in well preserved ultrastructure.
Analysis of selenium granules in Aeromonas hydrophila
Authors: Smith N. R. , Bramlett B. J. , Echer C. , Dixon B. A. 
Published: June 2020

Selenium (Se) is a naturally occurring nonmetallic element found in the environment as a result of fossil fuel combustion and industrial and agricultural processes. Although it is an essential trace element for plants and animals, high levels of soluble Se in agricultural drainage water have had deleterious effects on fish and waterfowl. The toxic forms of Se exist as selenate (+VI) and selenite (+IV) and both valence forms can be chemically reduced to insoluble, non-toxic elemental Se (O).A number of microorganisms are capable of reducing soluble Se to the zero valence state. Models have been proposed for using indigenous bacteria in water treatment systems to remove the toxic forms of Se via the reduction process. In order to realistically utilize this procedure, it is necessary to demonstrate that indeed the soluble Se is converted to elemental Se.
Possible artifacts due to sampling procedures in biological electron microscopy
Authors: Jakstys B. P. 
Published: June 2020

Artifacts in biological electron microscopy may originate from numerous sources, not the least of which may be the result of inadequate or inappropriate specimen sampling. Concern for adequate sampling most often arises when quantitative analyses such as morphometry or stereology, which require statistical evaluations, are to be performed. To obtain the most accurate and representative results, appropriate sampling should be done even if statistical analyses are not to be used. This applies to scanning and transmission electron microscopy.Depending on the specimen source, its nature, complexity of the study and preparation, random sampling should be carried out at various levels. In some instances, however, random sampling at the recommended levels is not feasible, as in the case of clinical specimens. In this situation the sampling should be done as is practicable. Ideally sampling should be performed on entire populations, as well as at the following levels: organ, tissue, block, section, grid, grid square, and different magnifications.