bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mitochondrial Reconstructions Based on Serial Thick Sections and HVEM
Authors: Paulin Jerome J. 
Published: June 2020

Within the past decade it has become apparent that HVEM offers the biologist a means to explore the three-dimensional structure of cells and/or organelles. Stereo-imaging of thick sections (e.g. 0.25-10 μm) not only reveals anatomical features of cellular components, but also reduces errors of interpretation associated with overlap of structures seen in thick sections. Concomitant with stereo-imaging techniques conventional serial Sectioning methods developed with thin sections have been adopted to serial thick sections (≥ 0.25 μm). Three-dimensional reconstructions of the chondriome of several species of trypanosomatid flagellates have been made from tracings of mitochondrial profiles on cellulose acetate sheets. The sheets are flooded with acetone, gluing them together, and the model sawed from the composite and redrawn.The extensive mitochondrial reticulum can be seen in consecutive thick sections of (0.25 μm thick) Crithidia fasciculata (Figs. 1-2). Profiles of the mitochondrion are distinguishable from the anterior apex of the cell (small arrow, Fig. 1) to the posterior pole (small arrow, Fig. 2).
An Image Reconstruction System Applied to High Voltage Microscopy
Authors: Johnson D. E. 
Published: June 2020

Increased specimen penetration; the principle advantage of high voltage microscopy, is accompanied by an increased need to utilize information on three dimensional specimen structure available in the form of two dimensional projections (i.e. micrographs). We are engaged in a program to develop methods which allow the maximum use of information contained in a through tilt series of micrographs to determine three dimensional speciman structure.In general, we are dealing with structures lacking in symmetry and with projections available from only a limited span of angles (±60°). For these reasons, we must make maximum use of any prior information available about the specimen. To do this in the most efficient manner, we have concentrated on iterative, real space methods rather than Fourier methods of reconstruction. The particular iterative algorithm we have developed is given in detail in ref. 3. A block diagram of the complete reconstruction system is shown in fig. 1.
High Resolution Structure Determination of Unstained Biological Molecules
Authors: Unwin P. N. T . , Henderson R. 
Published: June 2020

Structure determination of unstained biological molecules is made difficult by their sensitivity to damage by electrons. Because of this, resolution in an image of an isolated molecule, exposed to a dose small enough to avoid much damage, is limited by electron noise.It is well known however that statistical limitations of such a nature can be overcome in the case where the molecule forms part of a crystalline array. The information from the large number of unit cells can be combined so that the genuine detail is reinforced and random statistical fluctuations are averaged out.We have made use of this redundancy principle in determining, by Fourier methods, the projected structures of beef liver catalase and of the purple membrane from Halobacterium halobium. These specimens are about equally sensitive to irradiation and are typical of proteins (see fig. 1).Both specimens were immersed in glucose on the microscope grid.
Membrane Organelles in Developing Hamster Frontal Cortex
Authors: Tank Buschraann MB. 
Published: June 2020

Changes in the morphology of the protein-synthetic organelles in pyramidal cells from the frontal cortex were studied in the newborn, 5-, 10-, 15-, 20- day, and adult golden hamster (Mesocricetus auratus). The rough endoplasmic reticulum (RER) was of special interest since it forms the characteristic Nissl substance of adult neurons, as well as other occasional specializations including the subsurface cistern, the lamellar body, the nebenkem, the multilaminated body, the annulate lamella, and the spine apparatus. During the course of this investigation, a sequential pattern was noted in the appearance of the subsurface cisterns and the lamellar bodies, which were the only two specializations of RER observed.The animals were perfused with glutaraldehyde-paraformaldehyde in cacodylate buffer (pH 7.3) after the method of Peters. Tissue samples were subsequently post-fixed in 2% osmium tetroxide, dehydrated in acetone, and embedded in Epon-Araldite resin.
Replicative Forms of a MSV (FELV) Pseudotype Virus
Authors: Al-Adhami R. A. , Chapman A. L. 
Published: June 2020

We have reported on the replication of morphologically aberrant virus particles found in both Crandall cat kidney cell lines (CrFK2) and feline embryo fibroblasts (FEF) following infection with a pseudotype resulting from co-centrifugation and designated as MSV(FeLV). Another Crandall cell line (CrFKl) infected with this pseudotype did not show any transformation and only normal type C viruses were seen by electron microscopy. There appeared to be a direct correlation between transformation of the cells and the presence of aberrant progeny virus. There was evidence that there were two morphologically distinct normal type C viruses and an aberrant form replicating in those cells that were transformed.It was the purpose of this report to extend our study by using another pseudotype obtained from Dr. Fischinger that was prepared by infecting S+L- cells with FeLV. We then examined the infectivity and filtrability of the progeny virus.
Scanning Electron Microscopy of Non-Mechanical Cryofractured and Paraffin Sectioned Root Sheath of Epilated Human Hair
Authors: Uptgraft G. 
Published: June 2020

Scanning electron microscopy studies of human hair defects have been previously confined to descriptions of variation in cuticle morphology and general appearance of the shaft. While the general structure of the hair shaft, i. e., nodes, longitudinal invaginations and twists, occur in regular patterns for given diagnostic categories, there is some question as to the validity of using cuticle morphology as a diagnostic index, since variation within a given subject is usually greater than between subjects. Also, there is a limited amount of information to be obtained from such studies since the metabolically active part of the structure is not visualized. Consequently, the present investigation was initiated to delineate the root sheath through which the emerging hair shaft travels.The general structure of the root sheath is depicted using paraffin sections (Figs. 1,4), and non-mechanical cryofractured material (Figs. 2,3).
Morphology and Transplantability of Tumors Derived from Clones of the H-4II-E Rat Hepatoma Cell Line
Authors: Lovig C. A. , Nordquist R. E. , Muragishi H. , Bottomley R. H. 
Published: June 2020

Previous studies in this laboratory using the H-4II-E rat hepatoma cell line indicated that heterotransplantation of these cells into the cheek pouch of hydrocortisone treated hamsters resulted in the selection of cells with characteristic chromosome constitution and phenotype differing from the original H-4II-E cells.This study was designed to see if cells cloned from the H-4II-E cell line and differing in their genetic composition displayed differences in their ability to be transplanted into AxC rats and if the tumors produced by these cloned cell lines differed in their morphology.For this study five cloned cell lines were chosen based on their modal chromosome number and a sufficient number of T-75 flasks set up for each cell line such that transplantation experiments and karyotypic analysis could be carried out on cells of the same passage generation. Transplantation was done by innoculating 1x106 cells subcutaneously into each thigh of 10 AxC rats.
Ultrastructural Acridine Orange and Autoradiographic Studies in Acute Leukemia Bone Marrow Cells
Authors: Ahearn M. J. , Trujillo J.M. 
Published: June 2020

Previous studies have established that a high frequency of ultrastructural nuclear blebs occur in the bone marrow cells of acute leukemia patients with an aneuploid cytogenetic clone.Utilizing the nuclear bleb as an interphase morphological marker, nuclear probe studies with acridine orange and H3 thymidine were performed on these aneuploid leukemic blast cells. The deposition of Frenster's electron dense reaction product at the binding site of acridine orange to DNA has been employed to delineate the active extended euchromatic portions of the cell nucleus. These studies have indicated a variation in the pattern of the euchromatic binding in cells from acute leukemia patients bearing the nuclear bleb and an aneuploid clone when compared with the non-blebbed or diploid component of the bone marrow. The blebbed cells demonstrate a reduced acridine orange binding produce while similar staged non-blebbed cells are heavily marked as seen in Fig. 1. This observation is of interest in view of concomitant autoradiographic studies demonstrating a diminished H3thymidine incorporation observed ultrastructurally in the same nuclear blebbed cells.
Observation of Domains and Phase Separation in Hydrated Lipid Bilayers
Authors: Hui S. W. , Parsons D. F. 
Published: June 2020

The domain structure and phase separation in lipid single bilayers were observed directly by selective area electron diffraction (SAED) and selected reflection dark field electron microscopy (SRDFEM), using an environmental stage for a Siemens Elmiskop IA. The specimens were viewed in a fully hydrated state in the temperature range between 0°C and 50°C. Below the transition temperature, three orders of a hexagonal pattern were recorded, whereas diffuse rings only were seen above the transition temperature.Selective area electron diffraction were done by restricting the illumination area to few micrometers in diameter, using a pointed filament and a 10 μm second condenser aperture. Below the transition temperature of dipalmitoylphosphatidylchoiine bilayers, differentially oriented diffraction patterns were distinguishable between adjacent membranes areas (domains) five micrometers apart. Occasionally, two or more superimposed patterns were recorded from the same area, indicating the observation area covered several domains.
Fragmentation of the Actin Filaments by Acute Pressure Overload to the Right Ventricle of the Conscious Dog.
Authors: Adomian Gerald E. , Laks Michael M. , Swan H.J.C. 
Published: June 2020

We have postulated in a study of the isolated cat papillary muscle that the disparity between muscle length and sarcomere length may be the result of myofibrillar fragmentation. In contrast, Saphir and Karsner demonstrated in the rabbit myocardium subjected to an acute pressure overload, that segmentation or separation of intercalated discs occurred, and not myofibrillar fragmentation.In order to determine whether the myocardial fragmentation produced in the in vitro study has pathophysiological significance in the intact myocardium, tissues were studied from the right ventricle of the conscious dog subjected to an acute pressure overload.In order to produce the overload, we utilized a specially designed triple lumen pulmonary artery balloon distension catheter. This catheter can measure simultaneous pulmonary arterial and right ventricular pressures. The catheter was inserted through the jugular vein and wedged under flouroscopic control in a branch of the pulmonary artery. The balloon was situated in the main pulmonary artery.
Dormant and Germinating Diplodia Maydis Spores: Ultrastructure and Elemental Composition
Authors: Murphy Judith A. , Thompson Mary R. , Pappelis A.J. 
Published: June 2020

Diptodia maydis is one of the fungal pathogens causing stalk rot of corn. Previously we investigated the gross morphology of D. maydis on synthetic and natural substrates by SEM and established preparation procedures for D. maydis. The purpose of the present study was to compare the ultrastructure of D. maydis spores in thin sections with SEM results and in addition examine the elemental composition and distribution in dormant and germinating spores of D. maydis.SEM: Germinating and non-germinating spore cultures were double fixed in glutaraldehyde followed by OsO4. Samples were dehydrated in a graded series of alcohols thru 100%, then thru Freon TF and critical point dried with Freon 13 in a Bomar 900EX CPD. Specimens were mounted on SEM stubs, coated with carbon and PdAu and examined in a Cambridge Mark IIA SEM operated at 20 KV.TEM: Samples were double fixed with glutaraldehyde followed by OsO4, then dehydrated and embedded in Epon 812. Sections were stained with dipotassium tetramethyl osmate and examined in an Hitachi HU11AB TEM.
Sporocyte Development in the Musci. I. Three Genera of the Pottiaceae
Authors: Seabury F. , Mueller D.M.J. 
Published: June 2020

Sporogenes is in three members of the Pottiaceae: Weissia controversa Hedw., Acaulon muticum var. rufescens (Jaeg.) Crum, and Astomum muhlenberqianum (Sw.) Grout was studied using light, transmission and scanning electron microscopy with particular emphasis on the formation of the wall layers. McClymont and Larson, in a study of the mature spores of nine mosses representing seven families, found them to have walls of four layers. In this investigation four wall layers were observed in all genera studied. They are opaque layer, exine, perine and intine.The opaque layer begins to form while the spores are still contained within the sporocyte wall. Fig. 1 of Weissia exhibits a series of thin, trailing membranous projections which will later coalesce and flatten against the spore boundary. The opaque layer appears first on the distal surface of the spore.
The Mouse Testis as a Model for the Study of Age Related Fine Structural Changes
Authors: Johnson J.E. , Miquel J. 
Published: June 2020

In studying the morphology of aging cells, it is generally concluded that different changes occur in fixed postmitotic cells as compared to those cells which divide actively throughout life. The testis appears to be an excellent model for a comparative investigation of such changes, since it contains some cells which are essentially non-dividing in adulthood (Sertoli cells and interstitial cells) as well as other cells which divide continuously in mature animals (spermatogonia and spermatocytes).We have examined, by light and electron microscopy, the testes of numerous C57BL/6J mice at ages ranging from 3 to 30 months. All tissues were fixed by vascular perfusion with paraformaldehyde and glutaraldehyde mixtures in phosphate buffer.Sertoli cells (Fig. 1) and interstitial cells (Fig. 2) in aging animals contain a large number of dense bodies (presumably lipofuscin). On the other hand, dense bodies are not seen in spermatogonia, spermatocytes or spermatids (Fig. 1).
Electron Microscopic Study of Freshly Fixed and Time-Delay Fixed Tissues in Rat
Authors: Lim B. S. , Solomon J. D. 
Published: June 2020

In a pathology laboratory, many tissues which are submitted or made available for electron microscopic study are obtained from autopsy. Morphological changes due to postmortem delay which may not be visualized when studied with a light microscope are readily seen with the electron microscope. Because of this, it is important to make a comparative study of the freshly fixed and time-delay fixed tissues assimilating those obtained at autopsy. This work presents the results of morphological changes in the brain, heart, kidney, liver, and striated skeletal muscle of the rat with a postmortem time-delay of 24 hours. In the case of striated muscle the time delay was up to 48 hours before fixation.Methods and Materials A 62 day old male rat of the Sprague Dawley strain, weighing 410 grams was used in this experiment. The rat was anesthetized with nembutal and quickly opened. The brain, heart, liver, kidney, and a small piece of femoral muscle were quickly removed.
Potassium and Branchial Nerve Stimulation as Physiologic Regulators of Ciliary Motion in the Bivalve Mytilus Edulis
Authors: Paparo Anthony A. , Murphy Judith A. 
Published: June 2020

The lateral cilia(LC) on the gill of the bivalve Mytilus edulis are under neural control. Electrical stimulation (0.1V, 10Hz biphasic, 2msec duration for 3 min) of the branchial nerve(BN) increases the average rate of beating of LC, probably by a mechanism involving the release of 5-hydroxytryptamine (5 HT). Gills previously conditioned with [K]> 30mM enhanced cilioexcitatory effect of exogenous 5-HT.This study investigates the effect of [K] on endogenous neuronal release of 5-HT in intact and severed BN/gill preparations.Gill preparations were isolated and subsequent stroboscopic measurement of LC were made. When nerve stimulation was part of the experiment, the BN was exposed and an electrode placed at its point of departure from the visceral ganglion(VG).For SEM, specimens were doubly fixed in 3% glutaraldehyde in .05 M s-collidine, pH 7.2, for 30 min. washed, and then into Parducz fixative (6 parts of 2% aq. OSO4 to 1 part saturated aq. HgCl2) for 20 minutes. Samples were dehydrated through a graded series of alcohols through 100%, into Freon TF, and critical point dried in Freon 13 in a Bomar 900 EX CPD.
The Accumulation of Lipofuscin in the Epithelium of the Midgut of the Aging Housefly, Musca Domestica.
Authors: Duncan S.L. , Sohal R.S. , Allison V.F. 
Published: June 2020

Since somatic tissues in adult dipteran insects are entirely composed of post-mitotic cells, they are especially suited to studies concerned with structural alterations associated with aging. Previous reports mainly concerned with laboratory mammals and human tissues indicate an age-related accumulation of lipofuscin. Electron microscopic studies on aging houseflies have reported age-associated changes which include an increase in cellular autophagy and lipofuscin accumulation in nervous tissue, fat body and heart. The present study is concerned with electron microscopic and histochemical examination of the epithelium of the midgut of the housefly, Musca domestica. Special attention is given to the formation of lipofuscin and to the localization of acid phosphatase activity in aging animals.Tissue was acquired from the midgut of houseflies of known ages, fixed in gluteraldehyde and refixed in osmic acid. Samples were prepared by the method of Gomori for acid phosphatase localization. The preparations were embedded in Maraglas and studied with the Hitachi HUllB-2 transmission electron microscope.
Electron Probe X-Ray Microanalysis of Cardiac Muscle: Progress Report
Authors: Tormey J. McD. , Wheeler-Clark E. S. 
Published: June 2020

Myocardial contractility is primarily controlled by the moment to moment concentration of ionized Ca around the myofibrils. This concentration in turn is determined by a large number of factors, including gradients of various electrolytes across cell membranes and the concentrations of Ca in various subcellular compartments. The latter include sarcoplasmic reticulum (SR), mitochondria, binding sites associated with sarcolemmae and T-tubules, and binding sites within the sarcoplasm itself. A central problem in cardiac physiology has been to determine the functional interrelationships among these subcellular compartments.Electron probe x-ray microanalysis (EPMA) is the method of choice for directly measuring the concentrations within subcellular compartments of cells, and thus offers an unique opportunity to resolve the interpretive uncertainties inherent in alternative methods. Indeed, this method has yielded impressive results when applied by Soralyo et al. to a similar analytical problem in skeletal muscle.
A Polymer Thin-Film Technique to Study Phase Separation
Authors: Shaffer O.L. , Dimonie V. , El-Aasser M.S. , Vanderhoff J.W. 
Published: June 2020

There is a great deal of interest in the morphology of polymers. Polymer systems such as physical blends, copolymers and latexes of the core-shell type have become increasingly important in “designing properties”. of the final polymer. Phase separation examination is an excellent method of studying the morphology in these polymer systems.Normally phase separation in polymers has been studied by TEM. The standard sample preparation is to embed the solid polymer in epoxy and then microtome. Microtoming can create artifacts such as distortion due to the knife, cutting difficulty with a rubber phase and possible polymer-epoxy interaction. Because of the above mentioned problems a thin film technique has been developed to circumvent the microtoming procedure. A ruthenium tetrox-ide (RUO4) stain was also used to increase contrast.
Microanalysis of Airborne Lead Particulates in an Urban Industrial Environment
Authors: Doern F. E. , Wotton D. L. 
Published: June 2020

IntroductionWeston is a small residential neighborhood in the northwest quadrant of the City of Winnipeg (see Figure 1). The community, in addition to being surrounded by industrial activity, is also unusual in having a secondary lead smelter (Canadian Bronze Co. Ltd.) located within its residential area. There are two other secondary lead smelters in Winnipeg, both of which are also located in the northwest of the city. Concern about high levels of lead found in blood of children from Weston School, located some two blocks from Canadian Bronze and adjacent to moderately heavy traffic, prompted a rigorous air- and soil-sampling program. Following this there was considerable public/political debate and ultimately a sod/soil removal program at the school, and from a number of residential properties in the Weston area. The need to identify the lead source(s) came to the forefront again when lead-in-soil at Weston School was found to be approaching the maximum acceptable level (2600 μg/g for lead in urban soil) within twelve months following the “clean-up” operation.
In-Line Electron Holography in a Stem Instrument
Authors: Lin J.A. , Cowley J.M. 
Published: June 2020

It was suggested earlier that the idea of in-line electron holography, as proposed by Gabor in 1949 could now be implemented by use of a STEM instrument having a cold field emission gun. Reconstruction from holograms by computer methods, in place of the optical techniques suggested by Gabor, was shown to be effective for one-dimensional theoretically derived holograms. We have now applied the method of computerized reconstruction to digitized shadow image holograms recorded in our HB5 STEM instrument which has been modified to facilitate the process.The shadow image is formed on a phosphor screen in the detector plane. The light produced is amplified by means of an electrostatic image intensifier and viewed with a low-light-level TV camera. The output is digitized and stored by use of a TV-rate frame store and a PDP11/34 computer.
Development of a New 300kv Ultra-High-Resolution/High Performance Analytical TEM (H-9000)
Authors: Fujita H. , Ura K. , Sata H. , Miyauchi K. , Onai T. , Shii K. , Kubozoe M. 
Published: June 2020

Higher voltage is advantageous for better imaging resolution, better EELS performance and easier microscopy. Generally it results in a large scaled instrument with many associated problems. In the analytical area, there is a possibility of optimum voltage when a total performance balance is taken in consideration. We have developed a 300 KV TEM for both ultra high resolution and high performance analytical applications in view of these parameters. We have suceeded in making the instrument as compact as possible in order that it may improve the cost/performance ratio. We have taken full advantage of our ultra high voltage microscope experiences.Fig. 1 is a general view of the instrument. It is only 2.68m high and the same as conventional 200KV instruments. It consists of a 3-stage illumination and a 5-stage imaging lens system. This design allows the orientation matching for the diffraction pattern and TEM image throughout the entire magnification range.