bluuebunny/crossref_metadata_2025_split huggingface dataset:
Electron Microscopic Observations on Smooth Muscles of Cat Nicitating Membrane
Authors: Ishikawa Harunori , Yamada Eichi 
Published: June 2020

The cat nictitating membrane is commonly used for physiological and pharmacological study, since its smooth muscles are virtually all innervated by sympathetic nerves. Thus, morphological studies at the fine structural level have been focussed to the innervation of the nictitating membrane, but not to the smooth muscle proper.The nictitating membranes of adult cats were fixed in situ in protruded state with 2% formaldehyde and 2% glutaraldehyde in 0.1 M cacodylate buffer (pH. 7.3). The tissues were then dissected out to continue fixation in the same buffer. After rinse in 10% sucrose in the same buffer, the tissue blocks were postfixed in 1% OsO4 and embedded in Epon.
An Ultrastructural Study of the Proliferation Patterns of the Reserve Cells of the Human Cervix Uteri
Authors: Sohda Takanori , Saito Hiroshi , Asano Goro , Fukushi Katsunari , Suzuki Katsuya , Aihara Kaoru , Yajima Gompachi , Nagata Tokio 
Published: June 2020

Recently, the functional aspect as well as morphological aspect of the reserve cells in the cervix uteri drew much attention in view of the carcinogenesis in squamocolumunar junction. In this communication, the authors elucidate the ultrastructural features of the reserve cells in patients of various age groups visiting our university hospital and affiliated hospital.From conventional light microscopic point of view, the reserve cells tend to be pronounced in various pathological conditions, such as the persisting inflammation, proliferative disorders and irritation of hormones. The morphological patterns of the reserve cells from various stage and degree of irritation were observed.
Ultrastructural Similarities Between Down's Syndrome Prensile Dementia and Alzheimer's Disease
Authors: Ellis William G. , McCulloch John R. , Corley Charles L. 
Published: June 2020

The presenile dementia which almost invariably complicates Down's syndrome after the fourth decade is histologically identical to Alzheimer's presenile dementia. Ultrastructural changes in Down's syndrome dementia (DSD) have not been reported thus far. If DSD meets the rigid ultrastructural criteria established for Alzheimer's disease, then an important predictable age-dependent reservoir of material is available for multi-disciplinary studies of the earliest changes of Alzheimer's disease and aging in the human brain.Thin slices of brain tissue from a 54 years old woman with DSD were immersed in 4% phosphate-buffered paraformaldehyde (pH 7. 3) 12 hours after death, post-fixed in 1% phosphate-buffered OsO4 and embedded in Araldite. Silver impregnations of adjacent slices revealed the characteristic light microscopic findings of Alzheimer's disease: intra-neuronal neurofibrillary tangles, senile plaques, and granulovacuolar bodies.
Secretory Granules in Ectodermal Cells of Normal and Experimentally Treated Chorio-Allantoic Membranes
Authors: Leffingwell Thomas P. , Leffingwell Lois M. , Dauwalder Marianne 
Published: June 2020

The specialized membranes of the Golgi apparatus are thought to be responsible for the biosynthesis of complex (genetically-determined) heteropolysaccharides, coupling of such specific molecules with specific protein and/or lipid moieties, and secretion of the specialized materials. When studying the functions of the Golgi apparatus it may be advantageous to use tissues which are amenable to experimental modification.Selective displacement of the air space of the chicken egg has long been employed to render the chorio-allantoic membrane (CAM) accessible for experimental purposes. The ectoderm of the normal “dropped” CAM is composed of several types of cells, some of which contain Golgi apparatus that produce granules. These granules are moderately osmiophilic and stain positively for polysaccharides. With appropriate treatment, a thin layer of extracellular material which contains polysaccharides can be demonstrated on the surface of the ectoderm (Fig. 1).
Glutaraldehyde Polymerized with Ammonium Hydroxide as an Embedment
Authors: Pease Daniel C. 
Published: June 2020

Previously Peterson and Pease described the polymerization of glutaraldehyde with urea in the presence of substantial amounts of water to produce a useful embedment. For that reaction to yield an insoluble plastic a low pH (≅ 3.5-4.0) is required which we felt might be damaging to proteins, and so affect their subsequent morphology and stainability. Therefore, a way has been sought to develop a comparable plastic that could be polymerized at approximately neutrality.Ammonia is known to react with the carbonyl groups of aldehydes to form simple addition compounds which, however, are notoriously unstable. They tend to polymerize spontaneously to produce trimolecular products with a general formula as indicated.
Comparative Study of the Fine Morphology of Sensory Receptors in Aspidogaster conchicola and Cotylaspis insignis
Authors: Allison Venita F. , Ubelaker J. E. , Martin J. H. 
Published: June 2020

It has been suggested that parasitism results in a reduction of sensory structures which concomitantly reflects a reduction in the complexity of the nervous system. The present study tests this hypothesis by examining the fine morphology and the distribution of sensory receptors for two species of aspidogastrid trematodes by transmission and scanning electron microscopy. The species chosen are an ectoparasite, Cotylaspis insignis and an endoparasite, Aspidogaster conchicola.Aspidogaster conchicola and Cotylaspis insignis were obtained from natural infections of clams, Anodonta corpulenta and Proptera purpurata. The specimens were fixed for transmission electron microscopy in phosphate buffered paraformaldehyde followed by osmic acid in the same buffer, dehydrated in an ascending series of ethanol solutions and embedded in Epon 812.
The Lateral Giant Fiber to Motor Giant Fiber Synapse in Crayfish
Authors: Stirling Charles A. 
Published: June 2020

The lateral giant (LG) to motor giant (MoG) synapses in crayfish (Procambarus clarkii) abdominal ganglia are the classic electrotonic synapses. They have previously been described as having synaptic vesicles and as having them on both the pre- and postsynaptic sides of symmetrical synaptic junctions. This positioning of vesicles would make these very atypical synapses, but in the present work on the crayfish Astacus pallipes the motor giant has never been found to contain any type of vesicle at its synapses with the lateral giant fiber.The lateral to motor giant fiber synapses all occur on short branches off the main giant fibers. Closely associated with these giant fiber synapses are two small presynaptic nerves which make synaptic contact with both of the giant fibers and with their small branches.
Filamentous Component (Slime) in Coniferous Sieve Elements
Authors: Murmanis Lidija , Sachs Irving B. 
Published: June 2020

In the literature, it is agreed that in angiosperm sieve elements, a fibrillar, or filamentous, proteinaceous material is present, but the presence of this material in gymnosperms is not agreed upon. Some authors have reported filamentous material (slime) in Pinaceae by light and by electron microscopy. By contrast, some authors have found no structural component in conifers comparable to the sieve element fibrillar component in angiosperms.This report is an affirmation that filamentous material is present in Pinus strobus L. sieve elements. The finest filamentous unit, when measurable, appears to range from 40-60 A in diameter (Fig. 1, arrows). These filaments have a tendency to accumulate to various degrees. Generally, they aggregate in two; then the double structure measures 120-160 A in diameter (Fig. 1, double arrows), although the distance between two filaments is not constant.
The Hyphal Plexus of Psilotum Nudum Gametophytes
Authors: Walker D. K. , Davis R. W. 
Published: June 2020

The subterranean gametophyte thallus of Psilotum nudum, like some other lower vascular plants, forms a mycorrhizal-association with an endophytic fungus. The achlorophyllous prothallium is capable of synthesizing starch while growing in the dark. Presumably, the intracellular fungal hyphae within the prothallial cells aid the gametophyte in obtaining at least part of its basic organic nutrients.Each of the older Psilotum cells develops a single large body near the center of the cell lumen. These bodies are larger than the nuclei of the prothallial cells, but have similar affinities for acidiphilic dyes. This ultrastructural study of Psilotum gametophyte thalli was begun to determine the nature of these unusual bodies.
Crystalline Regions in Human Hepatocytes
Authors: Weide G. C. Vander , Burns W. A. 
Published: June 2020

The presence of cytoplasmic crystals in human hepatocytes is extremely rare and has been reported in a variety of pathological conditions. Only one other case of alcoholic fatty liver has been reported to our knowledge. As their nature, derivation, and significance are as yet unknown this report adds another example of these rare structures.The patient is a 38 year old negro male with the clinical diagnosis of chronic alcoholism and recurrent thrombophlebitis. Liver function tests were compatible with mild hepatic damage. These were returning to normal when a diagnostic liver biopsy without anesthesia was performed. Light microscopy showed mild fatty metamorphosis and focal portal fibrosis.
Ultrastructure and Development of Rodlet Cells in Gill and Intestine of Walleyed Pike (Stizostedion vitreum)
Authors: Leino Richard L. 
Published: June 2020

Tissues from the gut and gill of walleyed pike, ranging in age from birth to one year, reared in tanks separate from mature fish, were examined with the electron microscope for rodlet cells. While these cells are thought to be intercellular parasites (Rhabdospora thelohani) by some investigators, the present study supports the view held by others that they are secretory cells of the fish. Mature and previously undescribed immature rodlet cells were examined.Mature rodlet cells contain a basal nucleus with a supranuclear Golgi and associated saccules and vesicles. Large club-shaped sacs, the narrow parts of which converge upon an opening in the apex of the cell, comprise much of the cytoplasm. The sacs contain a dense-staining amorphous “core” substance surrounded by less dense material.
A New Model of Freeze Etching Apparatus
Authors: Akahori Hiroshi , Okamura Sadahiko , Nishiura Mitsugu , Uehira Kenzo 
Published: June 2020

A new model of freeze etching apparatus has been designed which enabled us to make both freeze fracture and freeze etching replicas of the biological specimens by easy simple procedures.This model is based on the principle of Bullivant's cold metal block method. It is composed of two-wedge-like brass blocks which are combined in a shape of rectangular prism with'a base 5.5 cm x 6. 0 era and a height of 7.5 cm.The lower block has a specimen stage to which a small specimen holder made of copper can be fixed. The specimen is put in a small hole of the specimen holder, and this holder is cooled in Freon 12.
Ultrastructure of Frozen Thin Sections of Skeletal Muscle
Authors: Demaree Richard S. , O'Donnell Terrance A. 
Published: June 2020

Reliable equipment has just recently become available which permits thin-sectioning of frozen specimens. We have been studying the effects of diet and exercise on skeletal muscle and are using cryoultramicrotomy as a check on fixation, dehydration, and embedding procedures.Canine triceps or pectineus muscles were obtained using either surgical or needle biopsy techniques. Fresh tissue was diced into 1mm cubes and either frozen fresh or fixed in 2.5% phosphate-buffered glutaraldehyde (5, 10, 15 or 30 minutes). Freezing by immersing specimens in liquid nitrogen consistently produced many ice crystals. However, freezing specimens by immersing them in isopentane cooled with liquid nitrogen produced fewer ice crystals. Cryoprotective agents, such as glycerine, yielded no appreciable improvement in preservation.Unfixed, frozen tissue was thin-sectioned with the specimen at -90° C, the knife at -30° C, clearance angle 5°, knife edge 55°, at a cutting speed of 2 mm/sec. Fixed, frozen muscle was thin-sectioned at the same temperatures with a knife clearance angle of 7°, knife edge 40°, at a cutting speed of lOmm/sec.
Morphology of the California Encephalitis Virus (CEV)
Authors: Vaituzis Z. , Reichelderfer P.S. , Hetrick F.M. 
Published: June 2020

Negative staining technique with potassium phosphotungstate (pH 7.2) and thin sections stained with uranyl acetate (pH 4.2) and lead citrate (pH 11.0) were used to study the fine structure of the prototype strain, BFS-283, of the California encephalitis virus group. The BHK-21 cell line was employed in this study for virus propagation. Monolayers were infected using a multiplicity of infection of 0.1. Following virus adsorption the cells were incubated at 37 C for 48 or 72 hrs. at which times samples were harvested for electron microscopy.Conventional methods for virus concentration and purification (e.g. centrifugation, cesium chloride gradient centrifugation, dialysis) failed to yield intact virus particles. These preparations contained disintegrating virions averaging 75 nm in diameter (Fig. 1). Treatment of such purified preparations with a 1.0% solution of sodium desoxycholate removed the lipid envelope and associated material revealing a nucleocapsid core of approximately 43 nm (Fig. 2).
As-1 Virus Adsorption to Cells and Spheroplasts ofSynechococcus Cedrorum
Authors: Desjardins Paul R. , Barkley Michael B. 
Published: June 2020

The recently described blue-green algal virus (AS-1) infects the unicellular algae,Synechococcus cedrorumandAnacystis nidulans. It has a complex morphology with a polyhedral head and contractile tail. The negative stain technique has been utilized to characterize its mode of adsorption to the cells of one of its hosts (S. cedrorum). Spheroplasts of this host were also prepared to determine whether the virus would adsorb to them as well as to normal cells.Synchronous cultures ofS. cedrorumwere induced by 3 - 4 days of light-dark alternation. When 75-85% synchrony had been obtained the cells were centrifuged and washed twice in a 0.5 M mannitol - 0.03 M phosphate buffer at pH 6.8. The cells were then treated with 0.05% lysozyme in buffer for 2.5 to 5.5 hrs at 39 C in the dark to induce spheroplast formation.
Hexachlorophene Influence on Ultrastructure of The CNS
Authors: Galey Frank R. 
Published: June 2020

Histological studies have demonstrated an hexachlorophene induced change of the cerebral white matter in rats (Kimbrough). The following report is an ultrastructural description of the changes as seen in monkeys, with an attempt to explain the molecular mechanism by which the changes develop.A dose of 3 mg of hexachlorophene per kg was administered subcutaneously to four juvenile (3-4 yrs) monkeys (Macaca mulatta) twice daily for 3 months. At the end of the experiment four treated monkeys and two stock control monkeys were sacrificed under anesthesia. The head region was perfused with 2.5% glutaraldehyde in a modified Tyrode's solution and tissues were sampled from spinal cord, superior colliculus, thalamus-callosum, cerebellum and optic nerve, and prepared for electron microscopic examination.Light microscopic examination revealed the development of cystic spaces in the thalamus-callosum samples from all of the treated animals. Optic nerve and spinal cord samples also demonstrated cystic spaces, but not as extensively as in thalamus-callosum.
Some Effects of Oxidant Air Pollutants (Ozone and Peroxyacetyl Nitrate) on the Ultrastructure of Leaf Tissues
Authors: Thomson William W. , Swanson Elizabeth S. 
Published: June 2020

The oxidant air pollutants, ozone and peroxyacetyl nitrate, are produced in the atmosphere through the interaction of light with nitrogen oxides and gaseous hydrocarbons. These oxidants are phytotoxicants and are known to deleteriously affect plant growth, physiology, and biochemistry. In many instances they induce changes which lead to the death of cells, tissues, organs, and frequently the entire plant. The most obvious damage and biochemical changes are generally observed with leaves.Electron microscopic examination of leaves from bean (Phaseolus vulgaris L.) tobacco (Nicotiana tabacum L.) and cotton (Gossipyum hirsutum L.) fumigated for .5 to 2 hours with 0.3 -1 ppm of the individual oxidants revealed that changes in the ultrastructure of the cells occurred in a sequential fashion with time following the fumigation period. Although occasional cells showed severe damage immediately after fumigation, the most obvious change was an enhanced clarity of the cell membranes.
Microanalysis of the Malpighian Tubule in the Silkworm Bombyx mori
Authors: Thurston E. L. , Russ J. C. , Teigler D.J. , Arnott H. J. 
Published: June 2020

Microanalysis in examining thin sections of biological tissue is providing new information in the areas of qualitative and quantitative histochemistry. This technique employs a SEM or TEM, equipped with an energy dispersive spectrometer and a transmitted electron detector. The crystal system in the silkworm was selected for this study in that it could serve as a model for bone formation, excretion, calcium transport, and oxalate metabolism in addition to its being suitable for the solving of some of the problems relating to microanalysis technique.Specimens were routinely fixed and embedded for TEM, and sections of approximately 1500Å were analysed on a SEM for 400 seconds at 30 KV at 0. 2 nA beam current. The spectra were computer - processed to smooth scatter and remove the contamination peak for silicon. In addition to problems involving contamination there has been uncertainty about the attainable levels of spatial resolution and sensitivity using thin sections.
Analysis of Contrast Reversal in SEM Images
Authors: Coutts M. D. , Levin E. R. 
Published: June 2020

On tilting samples in an SEM, the image contrast between two elements, x and y often decreases to zero at θε, which we call the no-contrast angle. At angles above θε the contrast is reversed, θ being the angle between the specimen normal and the incident beam. The available contrast between two elements, x and y, in the SEM can be defined as,(1)where ix and iy are the total number of reflected and secondary electrons, leaving x and y respectively. It can easily be shown that for the element x,(2)where ib is the beam current, isp the specimen absorbed current, δo the secondary emission at normal incidence, k is a constant, and m the reflected electron coefficient.
Texture and Artifacts in SEM Observations Due to Vapor Coating
Authors: Paulson G. G. , Pierce R. W. 
Published: June 2020

Specimen preparation techniques for scanning electron microscopy have not necessarily kept pace with the advances in instrumentation, especially in fields where quantitative measurements are important. Even though many operators have found that nonconducting surfaces can often be examined directly with low voltages and small beam currents, most commonly these surfaces are vapor-coated with 100 to 600 A of a noble metal alloy. More often than not, the coating procedures involve a bit of guesswork as to the final thickness and structure of the vapor coating. The purpose of this research was to illustrate the importance of close control on coating thickness and uniformity in order to minimize artifacts and distortion. Several noble metals and alloys were studied. The results for gold coatings are reported.Polystyrene spheres of statistically uniform diameters were dispersed on glass slides. The slides were rotated as they were coated by thermal deposition of Au from a W boat at a pressure of 2 x 10-5 torr in a standard oil diffusion pumped vapor coater.
Electron Microscopic Observation of Biological Specimens in Their Native State by Employing Cryogenic Techniques
Authors: Nei Tokio , Yotsumoto Haruo , Hasegawa Yoichi , Nagasawa Yuji 
Published: June 2020

In order to observe biological specimens in their native state, that is, still containing their water content, various methods of specimen preparation have been used, the principal two of which are the chamber method and the freeze method.Using its recently developed cold stage for installation in the pre-evacuation chamber of a scanning electron microscope, we have succeeded in directly observing a biological specimen in its frozen state without the need for such conventional specimen preparation techniques as drying and metallic vacuum evaporation. (Echlin, too, has reported on the observation of surface structures using the same freeze method.)In the experiment referred to herein, a small sliced specimen was place in the specimen holder. After it was rapidly frozen by freon cooled with liquid nitrogen, it was inserted into the cold stage of the specimen chamber.
A High Vacuum Scanning Electron Microscope
Authors: Bottoms W. R. 
Published: June 2020

The vacuum system of any electron optical instrument effects the contamination rate, electron source life, the quality of the electron source which can be employed, vibration amplitudes and stray magnetic field levels. It is particularly important for the scanning electron microscope where the object of primary interest is a specimen surface which can be altered by contamination. If we extend our investigations to employ Auger electron spectroscopy for surface chemical analysis, the requirements on the vacuum system are much more stringent. It is necessary that the chemical composition of the surface monolayer is not appreciably altered during the time required to take Auger spectra. The vacuum level required to accomplish this is dependent on the specimen material and the chemical composition of the ambient gas.Commercially available equipment can be modified to provide a vacuum environment maximizing the analytical capabilities of the instrument. The gas loads from the specimen and electron gun chambers of the instrument are minimized by utilizing only materials with favorable outgassing rates, and employing a gentle bakeout to remove water and other loosely bound gases on the system surfaces.
A New Design of Scanning Microscope
Authors: Sato Masayuki 
Published: June 2020

One of the practical approaches to the design of a scanning microscope is to employ the modular system for the recent versatile applications. The reasons are as follows: Each field of applications requires different sorts of instrument performance and even in a same field, the requirements may be changed as the research progresses. In order to meet these requirements, the instrument should be easily rearranged or modified, and as many new attachments as possible should be developed.The new scanning microscope JSM-50A has been designed and completed based on this concept. The modules used in this instrument are standardized in width, height and depth and in the mounted in a bin and power supply, and they constitute one unit which can be drawn out with the aid of slide type mounting channels from the cabinet for quick servicing. The width is selectable as single, double, triple and so on according to the built in circuit.