bluuebunny/crossref_metadata_2025 huggingface dataset:
The Effect of Activity on the Denervated Endplate
Authors: Pachter Bruce R. , Eberstein Arthur , Goodgold Joseph
Published: June 2020

Following damage to the peripheral nerve, the neuromuscular junction begins to degenerate, the muscle fibers become sensitive to acetylcholine over their entire length, the membrane electrical properties are altered and the muscle fibers become atrophic. It has been proposed that such anomalies might be due to inactivity, a lack of neurotrophic influence or a combination of both factors. The idea that In activity might be responsible for these changes has led to the use of electrotherapy to influence the healing process and promote nerve reinnervation. It has been recently suggested that electrical stimulation might be beneficial in preserving the neuromuscular junction in the denervated muscle. The present study was undertaken to determine morphologically the effect of electrical stimulation treatment on the endplates in denervated muscle.
Evidence for a Blood Ganglion Barrier in the Superior Cervical Ganglion of the Rat
Authors: DePace D. M.
Published: June 2020

The majority of blood vessels in the superior cervical ganglion possess a continuous endothelium with tight junctions. These same features have been associated with the blood brain barrier of the central nervous system and peripheral nerves. These vessels may perform a barrier function between the capillary circulation and the superior cervical ganglion. The permeability of the blood vessels in the superior cervical ganglion of the rat was tested by intravenous injection of horseradish peroxidase (HRP). Three experimental groups of four animals each were given intravenous HRP (Sigma Type II) in a dosage of.08 to.15 mg/gm body weight in.5 ml of.85% saline. The animals were sacrificed at five, ten or 15 minutes following administration of the tracer. Superior cervical ganglia were quickly removed and fixed by immersion in 2.5% glutaraldehyde in Sorenson's.1M phosphate buffer, pH 7.4. Three control animals received,5ml of saline without HRP. These were sacrificed on the same time schedule. Tissues from experimental and control animals were reacted for peroxidase activity and then processed for routine transmission electron microscopy.
Ultrastructure of the Surface Epithelium of the Polycystic Ovary in Constant Light Rats
Authors: Singh K. B. , Khosho F. K.
Published: June 2020

It is now well established that exposure of cyclic female rats to continuous light induces persistent estrus (PE), a syndrome which in many respects resembles the human polycystic ovary (PCO) syndrome. As in the human PCO, light microscopic studies of cystic ovaries of the constant light rat show numerous atretic follicles, and the surface epithelium grossly appears smooth and white. In the present study, we have utilized scanning (SEM) and transmission electron microscopy (TEM) to study changes on the surface epithelium of PCO in the constant light rat model.
Elemental Analysis in Disease Progression and Diagnosis
Authors: Barham S. S. , Tarara J. E.
Published: June 2020

Analytical electron microscopy is an important research tool that has found increasing use in disease diagnosis as well as investigation of disease progression. Energy dispersive x-ray spectrometers coupled with transmission, scanning, or scanning transmission electron microscopes have become accepted as useful aids to the pathologist in elemental identification and localization in human tissues. Many elements and compounds can be identified and localized in tissues using modifications of routine specimen preparation procedures for electron microscopy. This methodology limits the study of soluble electrolyte localization in tissues. Methods for localizing cellular cations or anions must still be performed using snap-freezing and vacuum drying procedures combined with ultracryomicrotomy or ion-capture cytochemistry such as pyroantimonate precipitation of cations. However, most metals and insoluble compounds can be localized in soft biological tissues by x-ray microanalysis while avoiding cryopreparative procedures that can be expensive, time consuming, and requisite of a high level of technical skill. Examples of this application of x-ray analysis of elemental content in soft tissues will be illustrated and discussed: metal loading of liver tissue associated with disease progression, sideroblastic anemias, pulmonary tissue inclusions, uptake of oil shale particulates by cultured cells, gold nephropathy, and chrysiasis.
Acid-Etching of Caries-Like Lesions Treated with Acidulated Phosphate Fluoride: An Sem and Microprobe Study
Authors: Hicks M. John
Published: June 2020

Clinical application of topical fluoride agents has proven to be an effective means of reducing the incidence and progression of dental caries. The caries-preventive potential of topical fluorides may be due to 1) the presence of fluoride-rich surface coatings, 2) incorporation of fluoride into hypomineralized enamel, 3) remineralization of the surface layer overlying enamel caries and 4) the bactericidal effect of fluoride. Acid-etching of enamel has been performed routinely to bond adhesive resin materials to sound enamel as a caries-preventive measure. Acid-etching of sound enamel results in 1) a loss of surface enamel (10 to 15μm), 2) exposure of enamel which is more reactive and 3) a tremendous increase in surface area.
Periodic Structure in the Matrix Protein of an Insect Virus
Authors: Mazzone H.M. , Engler W.F. , Zerillo R. , Bahr G.F.
Published: June 2020

The nucleopolyhedrosis virus (NPV) of the forest tent cater - pillar (Malacosoma disstria Hubner) has been analyzed in our laboratories. As a representative of the Baculovirus class, the NPV has virus particles enclosed with in a proteinaceous structure, the inclusion body.
Ultrastructural Changes in Human Cells Associated with Herpesvirus Latency and Reactivation in Vitro
Authors: Hung T. , Fang Z. Y. , Wigdahl B. , Rapp F.
Published: June 2020

Establishment and maintenance of virus latency is one of the most intriguing and challenging questions in virology. Significant gaps in our understanding of the manner in which herpes simplex virus (HSV) is maintained in the latent state and subsequently reactivated remain unanswered. O'Neill et al. developed an in vitro latency system1 in which HSV type 2 (HSV-2)-infected human embryonic lung (HEL) cells treated with cytosine arabinoside (ara-C) do not produce infectious virus for several days after drug removal. The period during which HSV-2 is inapparent can be extended by incubating infected cells at 39.5°C after drug removal. The advantage of this in vitro system is that it eliminates many complex factors associated with in vivo models and provides a simple reproducible method to examine latent HSV-2 infection.
Lactic Dehydrogenase Virus Infection in the Liver of Swiss Mice
Authors: Lattyak Michelle , Mumaw Virgil , Cross Sue
Published: June 2020

Lactic dehydrogenase virus (LDV) is an enveloped single-stranded RNA, Toga-like virus. Infections of LDV can occur naturally in all strains of laboratory and wild mice. The virus produces a stable life-long infection and maximum titers occur 24 hours after inoculation. LDV causes no clinical disease, but it can alter the host response to infectious agents and tumors. The virus particles have been found in the plasma and macrophages of the spleen, lymph node, and peritonium.
Diagnosis of Silica Induced Granulomatous Hypersensitivity
Authors: Mehard C. W. , Epstein W. L.
Published: June 2020

The underlying cause of a disease may not he readily apparent but may have a long history in development. We report one such case which was diagnosed with the aid of the analytical electron microscope.

The patient, a 48 yr. old white female, developed a tender nodule on the sole of her foot in December, 1981. Subsequently additional lesions developed on the same foot resulting in deep pain and tenderness. Superficial lesions also extended up to the knee on both legs. No abnormalities were revealed in blood tests or chest X-rays.
Differentiation of Skin Lesions in Acute Myeloid Leukemia by Myeloperoxidase Cytochemistry
Authors: Hanker J. S. , Ambrose W. W. , Moore J. O. , Giammara B. L.
Published: June 2020

Skin lesions are common in acute myeloid leukemia (AML) and occasionally are the presenting symptom. Usually these lesions are nonspecific, i.e. due to hemorrhage, infection, anemia, drug sensitivity or to corticosteroid therapy. Specific leukemic lesions are due to infiltration of the skin by myeloblasts or immature neutrophil series cells and can be complicated by infection.

Rapid identification of the type of lesion can be very important for if it is due to sepsis it may require immediate treatment by antibiotics or antiviral agents. If it is a specific lesion (leukemia cutis of AML) due to infiltration by myeloblasts, it may require a change in chemotherapy or adjunctive X-radiation or electron beam therapy.
Comparison of 2,2-Dimethoxypropane and Ethanol Dehydration: A Morphometric Evaluation
Authors: Buchanan Glenn M.
Published: June 2020

The use of acidified 2,2-dimethoxypropane (DMP) as a dehydration agent during the preparation of plant and animal tissues for transmission electron microscopy (TEM) was suggested by Muller and Jacks. Subsequently, Maser and Trimble recommended its use in specimen preparation for scanning electron microscopy (SEM). An extremely thorough investigation was conducted by Truter, et al, who concluded that "no increased degree of shrinkage could be detected" with the SEM and that organelle diameters were slightly greater after using DMP dehydration than when "conventional methods" were used.
Radiation-Induced Movement of a Mercury Stain at Room Temperature and Liquid Helium Temperature
Authors: Lamvik M. K. , Müller K. -H. , Weiss K.
Published: June 2020

Cryomicroscopy at liquid helium temperature has shown promise in protecting organic materials from the effects of radiation damage, and it might be expected that sensitive heavy-element stains would be similarly protected. We have made a preliminary study of a positively-stained protein specimen using the superconducting-objective electron microscope at Berlin. We have used the mercury stain TAMM, solubilized with penicillamine (TAMM-pen3), which is known to be radiation-sensitive, on tropomyosin paracrystals of the type made by Ohtsuki. Specimens were treated with 10μM TAMM-pen3 on the grid for times ranging from 15 min to 11 hr, then were washed with 1 ml water, blotted and dried. Staining time had little effect on our results. Here we are not studying the protein or stain specificity; our interest is in the movement of the stain, which we can clearly demonstrate.
Wavelength Dispersive Spectrometer Background Estimation with SI(LI) Energy Detector
Authors: Ingram F. Duane
Published: June 2020

Electron probe microanalysis of biological soft tissue canmonly is accomplished with either wavelength dispersive (WD) spectrometers or separately with a Si(Li) energy detector (ED), but rarely with both WD and ED simultaneously. Incompatibility of ED and WD spectrometers, resulting from basic differences in the methods x-rays are detected and identified and the way spectral information is presented to the investigator, makes combining ED and WD operation a difficult task. There also are operational differences that result from the variances in electron beam intensities required or permitted for operation of WD spectrometers and energy detectors. The larger electron beam currents typically used with WD spectrometers often are not tolerated by energy detectors.
Quantification in Elemental DIstributions of Light Atoms by EEL Image Analysis in Biological Sections
Authors: Ottensmeyer F. P.
Published: June 2020

Microanalysis by electron energy loss spectroscopy has gained momentum in the last few years with the utilization of more and more magnetic electron spectrometers coupled to dedicated or hybrid scanning transmission electron microscopes. Two approaches to analysis are the spectral evaluation of a single spot and the mapping of a single element over the entire image. In the first method, as in x-ray microanalysis, a finely focused electron beam is placed on a small area of the specimen. The impinging electrons traversing this spot subsequently provide a spectrum characteristic of the elemental content of the area.
Tem Imaging and Eels Measurement of Mass-Thickness Variations in Thick Foils
Authors: Whitlock R.R. , Sprague J.A.
Published: June 2020

Thick carbon foils (up to 12 microns) are presently being used In the laser fusion program as targets. The laser pulse Is focused to a 1 mm spot on the foil, which then accelerates by laser-driven ablation to a high velocity (100 km/s) in about 3x10-9 sec. Plash radiographs taken of the targets in flight reveal a definite rippling, which could be due to nonuniformities In either the laser beam, the target, or the acceleration process. To examine possible mass-thickness variations In the targets, sample pyrolytic graphite foils were examined in a JEM-200CX TEM/STEM instrument equipped with a Gatan electron-energy-loss spectrometer.
Tem of Climb-Dissociated Dislocations in Sapphire
Authors: Lagerlof K.P.D , Mitchell T.E. , Heuer A.H.
Published: June 2020

1. Introduction. Dislocation dipoles consisting of perfect edge dislocations are formed during basal slip in sapphire. These dipoles are unstable and break up by several diffusive processes;
Interaction of Noble Metal Fission Products with Pyrolytic Silicon Carbide
Authors: Lauf R. J. , Braski D. N.
Published: June 2020

Fuel particles for the High-Temperature Gas-Cooled Reactor (HTGR) contain layers of pyrolytic carbon and silicon carbide, which act as a miniature pressure vessel and form the primary fission product barrier. Of the many fission products formed during irradiation, the noble metals are of particular interest because they interact significantly with the SiC layer and their concentrations are somewhat higher in the low-enriched uranium fuels currently under consideration. To study fission product-SiC interactions, particles of UO2 or UC2 are doped with fission product elements before coating and are then held in a thermal gradient up to several thousand hours. Examination of the SiC coatings by TEM-AEM after annealing shows that silver behaves differently from the palladium group.
Control of Porosity in Spherical Precipitated Al2O3 Powders During Calcination
Authors: Tucker Dennis , Lee Soo Young , Hren J. J.
Published: June 2020

The advantages of using small spherical powders precipitated from solution to fabricate ceramic bodies could be substantial. For example, high grain densities and strengths can be achieved. Sintering time can be substantially reduced, high densities can be attained, etc. Not all of this potential has been so far realized. Some of the limitations encountered are the subject of this study, which monitored the morphological and microstructural changes accompanying calcination.
Applications of Electron Microscopy to Containment of Radio-Nuclides
Authors: Jantzen Carol M.
Published: June 2020

The long radioactive lifetime of the fission products in nuclear wastes requires that the materials be isolated from the biosphere for periods of 103 to 105 years. One method of accomplishing this is to consolidate the waste into a chemically stable solid form and to contain this within a multiple barrier canister which can be transported to a geologically stable repository for long-term storage. A number of candidate solid waste forms are being assessed to determine their suitability for incorporating various nuclear waste compositions and they include borosilicate glass (the current reference form), ceramics, high silica glasses, and cement.
Electron Microscopy of Nuclear Waste Glasses
Authors: Howitt D. G.
Published: June 2020

Of all the materials that have been put forward as suitable hosts for the isolation of nuclear waste the low melting temperature borosilicate glasses are perhaps the most attractive. They can be processed in a continuous stream, they maintain a reasonably high solubility for most of the various waste compositions and are particularly durable when compared to other materials that can be straightfowardly processed. Despite those advantages only a very few studies of this system have been concerned with the relationships between microstructure and properties in anything more than a cursory fashion and because of the intense competition between the various waste forms much of the early work was simply directed towards the reduction of empirical leach rates.
High Resolution Tem Studies of Coarsened Structures in a AU-53 at. %Ni, Alloy
Authors: Wu C.K.
Published: June 2020

The Au-Ni alloy system is characterized by the large diff erence in atomic size and number. Previous studies on the precipitation phenomena in this system showed that a mixture of Aurich and Ni-rich solid solution can be developed through di s continuous reaction during aging at temperatures between 400°C and 600°C. However, no detailed microstructural analysis has ever been reported. Thus, the purpose of the present study is to obtain the interfacial and chemical information of the coarsened structures in a Au-53 at. %Ni alloy by high resolution lattice imaging techniques of TEM.
The Microstructure of Solid Particle Erosion Debris
Authors: Brown Richard
Published: June 2020

Solid particle erosion is a surface degradation process. Many investigations of erosion utilized surface examination of either single large impacts or a multitude of smaller particle impacts. Little attempt was made to examine debris detached from the eroding surfaces. An investigation of erosion debris would detail the exact form in which material detached, its microstructure and defect content. From these parameters, the mechanisms of material loss can be identified. This paper reports on such an investigation for 30° solid particle erosion.
Electron Microscopy of Graphite Intercalation Compounds
Authors: Timp G. , Salamanca-Riba L. , Hobbs L.W. , Dresselhaus G. , Dresselhaus M.S.
Published: June 2020

Electron microscopy can be used to study structures and phase transitions occurring in graphite intercalations compounds. The fundamental symmetry in graphite intercalation compounds is the staging periodicity whereby each intercalate layer is separated by n graphite layers, n denoting the stage index. The currently accepted model for intercalation proposed by Herold and Daumas assumes that the sample contains equal amounts of intercalant between any two graphite layers and staged regions are confined to domains. Specifically, in a stage 2 compound, the Herold-Daumas domain wall model predicts a pleated lattice plane structure.
High Resolution Electron Microscopy of Sintered Ain
Authors: Tendeloo G. Van , Thomas G.
Published: June 2020

Sialon ceramics are widely studied because of their industrial interest due to their high temperature behaviour. AIN, being one of the edge components, has obtained little attention up until now mainly because it is difficult to prepare in a suitable form; moreover, it is a very poor sintering material. Very little is known about the properties or the exact structure. Recently Komeya and Tsuge succeeded in sintering 90wt% A IN and 10wt% SiO2 at 2100°. All the known tetrahedral A IN polytypes are based on the 2H (wurtzite type) structure where A1 and N are in tetrahedral coordination. When the metal to non-metal ratio deviates from one, different polytypes are formed by creating periodic stacking faults every nth layer.
Transmission Electron Microscope Observations of Dislocations in Hexagonal Ice
Authors: Falls Andrew H.
Published: June 2020

Despite the power of TEM in elucidating microstructure in solids, there have been relatively few studies of ice. The reasons are the difficulty of preparing thin specimens and of creating an environment in the microscope that can accommodate them. Another problem is the sensitivity of ice to an electron beam.
Microdiffraction Patterns of Small Metallic Particles II; Theoretical Analysis
Authors: Gómez A. , Schabes-Retchkiman P. , José-Yacamán M. , Ocaña T.
Published: June 2020

The splitting effect that is observed in microdiffraction pat-terns of small metallic particles in the size range 50-500 Å can be understood using the dynamical theory of electron diffraction for the case of a crystal containing a finite wedge. For the experimental data we refer to part I of this work in these proceedings.
The Identification and Characterization of Two Crystal forms in MDI/BDO Based Polyurethanes by Stem, TEM and Microdiffraction
Authors: Briber Robert M.
Published: June 2020

Polyurethanes based on 4,4'-diphenylmethane diisocyanate (MDI), 1,4-butane diol (BDO) and polypropylene oxide diol (PPO) form a segmented random copolymer which phase separates into hard and soft segment domains. The morphology of the hard segment (MDI/BDO) domains has been the object of considerable research because of the large influence of these domains on the mechanical properties of the material. A number of models based on wide and small angle x-ray and DSC studies ranging from highly ordered crystallites to paracrystalline domains have been proposed. In this study STEM and TEM imaging coupled with microdiffraction has revealed the presence of two distinct crystal structures with different morphologies.
Microdiffraction from out of Phase Domain Boundaries and Stacking Faults
Authors: Zhu J. , Cowley J.M. , Ye H.Q.
Published: June 2020

It has been pointed out1 that any discontinuity at the edge of a crystal or within a crystal may give rise to spot splitting in microdiffraction patterns.

The present work gives the basic theory for an antiphase domain boundary in Cu3Au and a twinning boundary in a f.c.c. crystal illuminated by a finite electron beam, which has a diameter of about 15Å. The treatment is based on the weak phase object approximation. These boundaries are planar faults. Multiplying a step function s(x) by the crystal potential expresses the discontinuity in the potential of the sample. When both sides of the boundary in the sample are illuminated by the finite coherent source and the boundary is parallel to the electron beam, the splitting of microdiffraction spots results from the convolution of the Fourier transform of the step function and the finite coherent source function.
Morphology of δ' in Dilute Al-Li Alloys
Authors: Baumanna S. F. , Williamsa D. B.
Published: June 2020

Shewmon noted that while diffusion controlled growth should result in precipitates tending towards a dendritic morphology, solid state precipitation from supersaturated solid solutions seldom results in particles exhibiting such shapes. Thus precipitate morphologies are very strongly governed by interface-stablizing phenomena such as anisotropic interfacial energies, lattice mismatch strain, slow interfacial reactions and interfacial diffusion.
The Nature of Delta Phase Precipitation in Inconel 718
Authors: Lin L. S. , Law C. C.
Published: June 2020

Inconel 718, a precipitation hardenable nickel-base alloy, is a versatile high strength, weldable wrought alloy that is used in the gas turbine industry for components operated at temperatures up to about 1300°F. The nominal chemical composition is 0.6A1-0.9Ti-19.OCr-18.0Fe-3Mo-5.2(Cb + Ta)- 0.1C with the balance Ni (in weight percentage). The physical metallurgy of IN 718 has been the subject of a number of investigations and it is now established that hardening is due, primarily, to the formation of metastable, disc-shaped γ" an ordered body-centered tetragonal structure (DO2 2 type superlattice).
Cluster Formation in thin Au Films Near the Metalinsulator Transition
Authors: Alessandrini E.I. , Laibowitz R.B. , Guarnieri C.R. , Voss R.F. , MacLachlan D.S.
Published: June 2020

Recently we have reported that measurements of the cluster size distribution near the metal-insulator transition in thin cermet Al-Al2O3 films show good quantative agreement with the predictions of 2 dimensional percolation theory. In this paper, we present an investigation of thin Au films (a non-oxidizing metal) near the metal-insulator transition and correlate the structure with electrical resistivity measurements. The TEM micrographs at different film thicknesses were digitized and computer enhanced. An automatic cluster analysis program was used for the the first time to identify clusters and compile size distribution for comparison with percolation theory.
A Gradient Field Spectrometer for Stem Use
Authors: Crewe A. V. , Scaduto Frank
Published: June 2020

An energy-loss spectrometer is a valuable component of the STEM and should be considered as an integral part of the electron optical system. As part of our effort to design a new STEM, we decided to take a fresh look at the problem.
Elemental Filtergrams Obtained by Means of Electron Energy Analyzer Combined with Image Storage System
Authors: Oikawa T. , Sasaki H. , Matsuo T. , Kokubo Y.
Published: June 2020

From the viewpoint of elemental analysis, the observation of the two-dimensional distribution of a specific element in the specimen is very interesting. The electron spectroscopic imaging technique in the TEM mode has been applied to biological and non-biological specimens. However, the technique needs a drastic modification of the instrument. In this paper, a simple method to obtain energy-filtered images (filtergrams) in the STEM mode is presented. Energy filtergrams were taken by means of a conventional magnetic sector type energy analyzer combined with an image storage system. The method requires no modification of the instrument.
The Ultrastructure of Monkey Gingival Epithelium
Authors: Sun C.N.
Published: June 2020

The present study demonstrates the ultrastructure of the gingival epithelium of the pig tail monkey (Macaca nemestrina). Specimens were taken from lingual and facial gingival surfaces and fixed in Dalton's chrome osmium solution (pH 7.6) for 1 hr, dehydrated, and then embedded in Epon 812.

Tonofibrils are variable in number and structure according to the different region or location of the gingival epithelial cells, the main orientation of which is parallel to the long axis of the cells. The cytoplasm of the basal epithelial cells contains a great number of tonofilaments and numerous mitochondria. The basement membrane is 300 to 400 A thick. In the cells of stratum spinosum, the tonofibrils are densely packed and increased in number (fig. 1 and 3). They seem to take on a somewhat concentric arrangement around the nucleus. The filaments may occur scattered as thin fibrils in the cytoplasm or they may be arranged in bundles of different thickness. The filaments have a diameter about 50 A. In the stratum granulosum, the cells gradually become flatted, the tonofibrils are usually thin, and the individual tonofilaments are clearly distinguishable (fig. 2). The mitochondria and endoplasmic reticulum are seldom seen in these superficial cell layers.
On an Application of the Metallurgical Stage to Chromosome Morphology
Authors: Hoskins Godfrey C.
Published: June 2020

The first serious electron microscooic studies of chromosomes accompanied by pictures were by I. Elvers in 1941 and 1943. His prodigious study, from the manufacture of micronets to the development of procedures for interpreting electron micrographs has gone all but unnoticed. The application of todays sophisticated equipment confirms many of the findings he gleaned from interpretation of images distorted by the electron optics of that time. In his figure 18 he notes periodic arrangement of pepsin sensitive “prickles” now called secondary fibers. In his figure 66 precise regularity of arrangement of these fibers can be seen. In his figure 22 he reproduces Siegbahn's first stereoscopic electron micrograph of chromosomes.

The two stereoscopic pairs of electron micrographs of a human chromosome presented here were taken with a metallurgical stage on a Phillips EM200. These views are interpreted as providing photographic evidence that primary fibers (1°F) about 1,200Å thick are surrounded by secondary fibers (2°F) arranged in regular intervals of about 2,800Å in this metanhase human chromosome. At the telomere the primary fibers bend back on themselves and entwine through the center of each of each chromatid. The secondary fibers are seen to continue to surround primary fibers at telomeres. Thus at telomeres, secondary fibers present a surface not unlike that of the side of the chromosome, and no more susceptible to the addition of broken elements from other chromosomes.
Uniformity of Magnification from Different Electron Microscopes
Authors: Hoskins Godfrey C. , Williams V. , Allison V.
Published: June 2020

The method demonstrated is an adaptation of a proven procedure for accurately determining the magnification of light photomicrographs. Because of the stability of modern electrical lenses, the method is shown to be directly applicable for providing precise reproducibility of magnification in various models of electron microscopes.

A readily recognizable area of a carbon replica of a crossed-line diffraction grating is used as a standard. The same area of the standard was photographed in Phillips EM 200, Hitachi HU-11B2, and RCA EMU 3F electron microscopes at taps representative of the range of magnification of each. Negatives from one microscope were selected as guides and printed at convenient magnifications; then negatives from each of the other microscopes were projected to register with these prints. By deferring measurement to the print rather than comparing negatives, correspondence of magnification of the specimen in the three microscopes could be brought to within 2%.
Ultrastructural Localization of Acid Mucosubstance in Skeletal Muscle
Authors: Dougherty William J. , Spicer Samuel S.
Published: June 2020

In recent years, considerable attention has focused on the morphological nature of the excitation-contraction coupling system of striated muscle. Since the study of Porter and Palade, it has become evident that the sarcoplastic reticulum (SR) and transverse tubules constitute the major elements of this system. The problem still exists, however, of determining the mechamisms by which the signal to interdigitate is presented to the thick and thin myofilaments. This problem appears to center on the movement of Ca++ions between myofilaments and SR. Recently, Philpott and Goldstein reported acid mucosubstance associated with the SR of fish branchial muscle using the colloidal thorium dioxide technique, and suggested that this material may serve to bind or release divalent cations such as Ca++. In the present study, Hale's iron solution adapted to electron microscopy was applied to formalin-fixed myofibrils isolated from glycerol-extracted rabbit psoas muscles and to frozen sections of formalin-fixed rat psoas muscles.
The Prostate of the Four-Eyed Opossum
Authors: Hruban Z. , Martan J.
Published: June 2020

The prostate of the four-eyed opossum (Philander, Brisson) resembles grossly and histologically that of Didelphis virginiana (J. Exper. Zool. 160: 81, 1965).

The cells of the first segment and apocrine globules contain abundant glycogen, iron containing granules and PAS-positive granules with complex ultrastructure (Fig. 1). The complex granules contain glycogen-like particles and crystalline material with 90 A periodicity.

The second segment contains A cells and B cells. The granules of A cells are PAS positive and contain fibrillar material. The granules in B cells are rich in protein. Mature granules contain hexagonally-packed fibrils (Fig. 2). Immature granules contain particles attached to lines which are about 40 A thick (Fig. 3). The particles are 85 A long and 65A wide. Transitional forms are found (Fig. 4).

The cells of the third segment contain abundant glycogen and scanty organelles. The lumina are filled with parallel layers of membranes. The catalase content of the third segment is thirty times higher than that of the liver.

Each segment is subdivided into zones with histochemical and ultrastructural variations.
The Fine Structure of Brunner’s Glands in the Human
Authors: Lesson T. S. , Leeson C. R.
Published: June 2020

Duodenal submucosal glands occur in all mammals but show species differences both in their extent and histological structure. Surgical biopsy specimens were obtained from five individuals aged from 37 to 56 with no history of duodenal abnormality. In all cases the patient was starved for four to eight hours prior to operation and the biopsies were taken from the second part of the duodenum immediately proximal to the opening of the common bile duct. The tissue was prepared both for light and electron microscopy.

By light microscopy Brunner’s glands in the human appear as masses of coiled tubules in the submucosa with ducts opening into the bases of intestinal glands. Component cells are characteristically mucous in type with dark, irregular, basally-located nuclei and clear, foamy cytoplasm.
Some Ultrastructural Aspects of Vensus’s-Flytrap
Authors: Schwab Daniel W. , Scala James , Simmons Evelyn B.
Published: June 2020

Recently a study was begun in this laboratory on the insectivorous Venus's-flytrap (Dionaea muscipula Ellis) at all levels of microscopy, with emphasis on ultrastructure. Two features, among others, that stand out in the electron microscope after glutaraldehyde-osmium tetroxide fixation are: (1) a highly-convoluted plasmalemma in the digestive gland cells and (2) a tubular network in the cell walls of the trap lobe.

The cell walls and plasmalemma of the digestive gland appear to be highly specialized, in that numerous microvilli-like outgrowths on the walls cause a myriad of invaginations in the plasmalemma (Fig. 1). Thus the plasmalemma has a tremendous surface area which would facilitate its functioning as a secretory and absorptive membrane. Also of interest in the digestive gland are the two distinctly different cell wall inclusions seen in Fig. 2. The bundle of tubular inclusions (Fig. 2, lower half) are apparently specialized plasmodesmata which do not traverse cell walls in the usual manner but run laterally around the cell.
Loop DNA of the Tradescantia Chloroplast
Authors: Grun Paul
Published: June 2020

Chloroplasts were purified from other organelles of chopped leaf tissue of Tradescantia paludosa by differential centrifugation. DNA was purified by lysing of plastids in sodium lauryl sulphate followed by phenol extraction, treatment with ribonuclease, and dialysis. The plastid DNA was mounted on electron microscope grids following flotation in cytochrome c by the method of Freifelder and Kleinschmidt (1965), and shadowed with uranium oxide at an eight degree angle while the grids rotated on a turn-table. Electron micrographs showed a pattern of variable-lengthed loops, from ca. 0.1 through 1.4 microns in length. Typically four to seven such loops radiated from a common center or lay concentrically nested, but attached to a common center. The total length of DNA of a single bundle of loops typically ranged from four to six microns. Occasional long configurations were found resulting from the connection of different loop complexes to one another. Free ends were present, and no single closed rings of the type seen in mitochondrial DNA were found. The width range was that of the double-stranded form, although in certain areas denatured single strands were visible.
Studies on Spontaneous Mammary Tumors in High-Leukemia-Strain Mice and on Mammary Tumors Induced by Mouse Leukemia Virus in Low-Leukemia-Strain Mice
Authors: Yumoto T. , Young L. , Williams W. C. , Dmochowski L.
Published: June 2020

Murine leukemia type C virus particles were found in a spontaneous mammary gland medullary carcinoma of a 9-month-old high-leukemia AKR strain mouse (Fig.1). Similar virus particles were observed in a spontaneous mammary gland adenocarcinoma of a 12-month-old SJL/J high-leukemia-strain mouse (Fig.2). No virus particles could be seen in another mammary tumor of similar type in a 13-month-old SJL/J strain mouse nor in a spontaneous mammary squamous cell carcinoma of a 9-month-old NZB/BL high-leukemia-strain mouse.

Mammary tumor type B virus particles were observed in a mammary gland adenocarcinoma of a 6-month-old AKR strain mouse inoculated when newborn with Moloney leukemia virus (Fig.3).

No virus particles could be found in a mammary gland medullary carcinoma of a 12-month-old BALB/c low-leukemia and low-mammary-cancer-strain mouse inoculated with Moloney virus.

Mammary gland medullary carcinomas developed in two BALB/c strain 5-and 6-month old mice inoculated with Rauscher leukemia virus. Murine leukemia type C virus particles were observed in both tumors (Fig.4).
Three Dimensional Images of Cardiovascular Elements With Freeze Etching
Authors: Oscar Kreutziger G. , McAlear James H.
Published: June 2020

Mouse heart muscle was prepared by freeze etching. This involves a new device ( McAlear and Kreutziger, this volume) and technique for specimen preparation. These have permitted the production of replicas as in the figure on the reverse side which have a three dimensional aspect similar to an artist's presentation of tissue sub structure. Muscle filaments can be seen in longitudinal and transverse section almost as a conventional section yet the capillary appears to arise out of the muscle. The sutures of the enclosing endothelial cells appear to wander over the upper and lateral surface of the capillary to the cross fracture plane where they and the lumen are seen in cross section. In the foreground the endothelium continues as a replica of the inner facing membrane of the outer endothelial layer. All possible membrane surfaces are seen in various replicas.
The Effect of Insulin on Mitochondrial Particles
Authors: Silver Burton B. , Hall James C.
Published: June 2020

Correlative biochemical and structural studies have shown that insulin and Mg++ may act to alter the configuration and also enhance the efficiency of coupled phosphorylation in sonicated fragments of diabetic rat liver mitochondria. The diabetic preparations had consistently lowered P:O ratios which returned to normal values with addition of insulin in vivo or in vitro. Optimum coupling and structural changes with insulin required a Mg++ concentration of 5 × 10−5 M. Insulin remained effective diluted to a concentration of 2 × 10−4 I.U. per ml. Glutathione, bovine serum albumin, and Zn++ were ineffective in producing either coupling or structural changes. There seems to be a synergistic action of insulin and Mg++ in restoring P:O ratios in diabetic particles while simultaneously altering the structure toward normal control appearances. Fragments negatively stained with phosphotungstate indicated that the normal particles had well defined cristae with numerous evenly distributed, stalked subunits, 90 Å in diameter.
Hepatic Ultrastructure Changes Induced by Lithocholic Acid
Authors: Zaki F. G.
Published: June 2020

Addition of lithocholic acid (LCA), a naturally occurring bile acid in mammals, to a low protein diet fed to rats induced marked inflammatory reaction in the hepatic cells followed by hydropic degeneration and ductular cell proliferation. These changes were accompanied by dilatation and hyperplasia of the common bile duct and formation of “gallstones”. All these changes were reversible when LCA was withdrawn from the low protein diet except for the hardened gallstones which persisted.

Electron microscopic studies revealed marked alterations in the hepatic cells. Early changes included disorganization, fragmentation of the rough endoplasmic reticulum and detachment of its ribosomes. Free ribosomes, either singly or arranged in small clusters were frequently seen in most of the hepatic cells. Vesiculation of the smooth endoplasmic reticulum was often encountered as early as one week after the administration of LCA (Fig. 1).
Mitochondria and Cytocrome Oxidase in Copper Deficiency in the Rat
Authors: Goodman Joseph R. , Dallman Peter R.
Published: June 2020

Weanling Wistar rats reared on copper deficient diet, in addition to becoming anemic, developed a marked depression of cytochrome oxidase activity in certain tissues. Cytochrome oxidase was determined in homogenates by the method of Cooperstein and Lazarow, and estimated in mitochondrial fractions by means of spectral analysis. Activities of this enzyme in cooper deficient rats, expressed as percent of control concentrations, was 27% for heart muscle and 34% for liver, while other mitochondrial cytochromes were not depressed. This enzyme, which contains copper in its molecular structure is found exclusively in mitochondria. The heart with its large decrease in cytochrome oxidase activity was at the same time hypertrophied and very firm in its consistency.
Microtubular Formations of Endoplasmic Reticulum in Human Pathological Tissues
Authors: Chandra S. , Kuzmic S. , Brandt P. M. , Monroe J. H.
Published: June 2020

A certain modification of the endoplasmic reticulum has been described in liver in severe hyperlipidaemia and in cells from a culture of peripheral blood leukocytes of a leukemic patient. Recently cytoplasmic structures presumed to be related to virus synthesis have been reported in monkey kidney cells infected with rubella virus and in the Sticker sarcoma of the dog. During our studies with fifteen cell lines originating from different human tissues, similar cytoplasmic structures have been observed and interpreted as modifications of the endoplasmic reticulum (ER).

A number of cell lines have been established from either the peripheral blood leukocytes, lymph nodes, or spleens and thymuses of cancerous or noncancerous patients. Both biopsy and autopsy materials have been used. Tissues of in vitro or in vivo origin were processed for electron microscopy in the usual way.
Effects of Photochemical Smog on Alveolar Lung Tissues of Young and Old Mice — An Electron Microscope Study
Authors: Bils R. F. , Evans M. J.
Published: June 2020

Photochemical smog was produced by irradiating a mixture of propylene (8 ppm), nitric oxide (2.8 ppm), carbon monoxide (25 ppm) and water vapor (20%) with ultraviolet lamps in the 1000 cu. ft. reaction chamber of the California Vehicle Pollution Laboratory. The total oxidant concentration and reaction patterns approximated those of a heavy smog day. Male A, Swiss-Webster and C-57 strains of mice exposed for 3-4 hours showed ultrastructural alterations of alveolar lung tissue similar to the heavy natural smog exposures (Bils, 1966). Wall cells became highly vacuolated and some lining membranes disrupted in 8-month-old mice, but only temporarily. Delaying sacrifice only 12 hours allowed the lungs to return to normal. However, permanent changes occured in 15-month-old mice. Fair recovery of smog-disrupted alveolar and capillary lining cells occured, but few wall cells remained. More extensive disorganization of wall cell cytoplasm and lining membranes was seen when the 20-month-old mice breathed synthetic smog; delayed sacrifice revealed further damage and cell debris in the alveoli.
The Ultrastructure of Metastatic Human Mammary Carcinoma After Prolonged Estrogen Therapy
Authors: Watson John H.L. , Swedo John L. , Talley R.W.
Published: June 2020

A preliminary study of human mammary carcinoma on the ultrastructural level is reported for a metastatic, subcutaneous nodule, obtained as a surgical biopsy. The patient's tumor had responded favorably to a series of hormonal therapies, including androgens, estrogens, progestins, and corticoids for recurring nodules over eight years. The pertinent nodule was removed from the region of the gluteal maximus, two weeks following stilbestrol therapy. It was about 1.5 cms in diameter, and was located within the dermis. Pieces from it were fixed immediately in cold fixatives: phosphate buffered osmium tetroxide, glutaraldehyde, and paraformaldehyde. Embedment in each case was in Vestopal W. Contrasting was done with combinations of uranyl acetate and lead hydroxide.
The Crystal Packing of Thyroglobulin
Authors: Labaw L. W.
Published: June 2020

The unit of packing of thyroglobulin, the iodine-containing protein of the thyroid gland, in crystals appears to be an approximate sphere 230 Å in diameter (Figure 1). The size of this packing unit corresponds to a molecular weight of about 5,000,000 whereas the molecular weight of the thyroglobulin molecule is 660,000. The possibility that these packing units are aggregates of molecules has been examined in the electron microscope using positive staining (Figure 2), negative staining (Figure 3), and shadowing (Figure 4).

Thyroglobulin crystallizes when the ammonium sulfate concentration is about 40% of saturation. The crystals can be freed of obscuring uncrystallized molecules by washing them with an ammonium sulfate solution of higher concentration. The washed crystals are then put on a substrate and air-dried (Figure 1). This high salt concentration makes examination of the packing unit for substructure difficult so the crystals were adsorbed onto substrates which were then flooded with 0.2% PTA and mopped. The resulting positively stained preparations suggest that the linear aggregates of packing units, which are associated side-by-side to make up the crystal, are actually helices. This is confirmed both by negatively staining such specimen screens by following the 0.2 PTA rinse with one of 2% before mopping (Figure 3), and by shadowing the 0.2% PTA rinsed and water washed screens with platinum (Figure 4).
Effect of the Substrate on Image Contrast in High Resolution
Authors: Eisenhandler Claire B. , Siegel Benjamin M.
Published: June 2020

A high resolution electron microscope intended for the study of thin biological molecules is currently under development at Cornell University. Previously reported computer calculations of the molecular images to be expected from this instrument indicate that considerable atomic structural detail would be visible in the image, specifically that atoms having Z≥6 would exhibit sufficient phase contrast to be observed and interatomic spacings ≳2Åwould be resolved. These earlier calculations did not consider the effect on the image of the substrate supporting the specimen. Results of a theoretical investigation of the substrate and computer calculations are presented here.
The Use of the Scanning Electron Microscope for the Examination of Sectioned
Tissue
Authors: McDonald L.W. , Pease R.F.W. , Hayes T.L.
Published: June 2020

In previous studies from this laboratory the scanning electron microscope has been used to examine biological materials in the cathodo-luminescense and secondary electron modes. In these studies intact cells or even entire insects have been examined, some in the living state. Epithelial surfaces have been exposed and examined. Prior to the work to be described, no reports of the examination of tissue sections in the scanning electron microscope have been found, although sufaces of solid one millimeter cubes of tissue have been examined.

In the present work blocks of solid tissue fixed in buffered aldehyde have been dehydrated in graded alcohols, embedded in paraffin, section at 4μ and examined successfully in the scanning electron microscope. These sections have been over 1 cm square and have been stained for subsequent comparative examination with the light microscope. With the scanning electron microscope in the secondary electron mode, magnifications of X5,000 have been found useful. In addition to the increased resolution as compared to the light microscope, a three dimensional image is obtained. An advantage over the conventional electron microscope is that tissue areas 1,000 times greater may be examined in the large sections without any obscuring grid bars, again with the three dimensional image. With the cathode ray display tube used, magnifications range from X30 to over X20,000