bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Ultrastructure of the Distal Tubule of Amphiuma: A Tem and Sem Study
Authors: Biemesderfer D. , Stanton B. , Kashgarian M. , Giebisch G. 
Published: June 2020

Although the surface distal tubule of Amphiuma means has been used in transport and electrophysiology studies, a detailed description of its ultrastructure is lacking. In vitro microperfusion studies have identified three physiologically distinct segments. This study describes the morphology of the distal tubule of Amphiuma by transmission and scanning electron microscopy.Kidneys of ten animals were perfused via the aortic and portal vessels with amphibian ringers followed by fixative containing 1% paraformaldehyde, 1.25% glutaraldehyde, 0.05 M sucrose, 2% T40 Dextran, in 0.05 M Na cacodylate buffer, pH 7.2. For TEM, the kidneys were processed as described previously. For SEM, the tissue was osmicated, dehydrated and critical point dried using CO2
Membranous Glomerular Lesions
Authors: Spargo Benjamin H. 
Published: June 2020

Non-inflammatory basement membrane changes constitute a growing number of glomerular peripheral capillary wall lesions. The widely varying nature of the basement membrane changes is important, both because of the contrasting prognosis of the different lesions and the new insights as to the pathogenesis.Marked changes in the capillary wall in the absence of deposits causing thickening are seen in progressive hereditary nephritis. This lesion, frequently associated with Alport's syndrome, exhibits autosomal dominant inheritance, neural hearing loss, and ocular abnormalities. The renal disease presents clinically as hematuria and proteinuria, and has a poor prognosis.
Mass Measurement of Macromolecular Complexes with the Stem
Authors: Wall J. S. , Hainfeld J. F. 
Published: June 2020

Mass measurement with the Scanning Transmission Electron Microscope (STEM) is a technique with wide application which has been developed in several laboratories. It is especially useful for particle identification in micrographs or in measurements of mass per unit length and mass distribution within a complex object.The accuracy of mass measurements is determined by random errors (Counting statistics, substrate thickness variation) and systematic errors (biochemical degradation, salt, specimen preparation artifacts, radiation damage). Random errors can be estimated from previous studies and range from 1-10%.
Low Temperature X-Ray Microanalysis of Solid Biological Samples: Prospects and Problems
Authors: Echlin Patrick 
Published: June 2020

IntroductionThe advantages to be gained from using low temperatures in the preparation, examination and analysis of biological materials are well documented. The low temperature approach is particularly important in the analysis of low atomic number diffusible elements (x-ray microanalysis, electron spectroscopy and secondary ion analysis) and low molecular weight compounds (autoradiography, fluorescent microscopy and laser probe analysis). A recent paper discusses the application of these and other methods to the analysis of solid organic samples. This present discussion centres on the advantages and disadvantages of carrying out x-ray microanalysis on frozenhydrated (as distinct from frozen-dried) biological materal, with particular emphasis to solid samples. Two main methods have evolved for the analysis of frozen hydrated biological material; the use of frozen-hydrated sections and frozen-hydrated fracture faces. There are merits and short comings to both approaches and for any given tissue both methods can be complementary, neither are mutually exclusive.
Defect Studies in Solar Cell Silicon
Authors: Cunningham B. 
Published: June 2020

IntroductionOne of the requirements for low-cost silicon solar cells is that the silicon substrates be relatively inexpensive (compared to standard Czochralski and float-zone wafers). This requirement has led to the development of a number of techniques for growing silicon ‘ribbons’, e.g. edge defined film-fed growth (EFG), silicon-on-ceramic (SOC), ribbon-to-ribbon (RTR) and dendritic web. Details of these and other growth techniques can be found in ref. Most of the growth methods produce silicon ribbons which contain relatively high densities of structural defects, such as grain boundaries, twin boundaries and dislocations. In addition, small amounts of chemical impurities are introduced into the ribbons during growth from sources such as shaping dies (EFG), substrates (SOC, RTR), heat shields, etc.
Invariant Line and Loss of Coherency in Mo(C) System
Authors: Lang Jean-Marc 
Published: June 2020

This paper reports a detailed study of the loss of coherency of h.c.p. Mo2C precipitates in an b.c.c. Mo matrix. The existence of an invariant line in the phase transformation is experimentally verified.The experiments were performed on a very pure Mo - 300 at. ppm C alloy, quenched from 2300K at a rate of 2500K/s to prevent heterogeneous nucleation. The specimens were subsequently annealed 1h at 1073K.
Electron Microscopy in Medicine
Authors: Stanley Bennett H. 
Published: June 2020

Medicine can be regarded as an applied biological science, much as engineering involves applications of the physical sciences. Just as the physical sciences and engineering participate in regenerative feed-back loops in which each field strengthens the other as well as itself, so medicine and biology depend on each other. Fundamental conceptual and technical advances in biology come to be reflected in medicine.How did the revolution in cytology brought to pass by electron microscopy come to pervade the field of medicine? Before physicians, or anyone else, can use a field of knowledge, they must know it. Large scale dissemination of a complex set of concepts through a professional body is accomplished most thoroughly by incorporation and integration of that field into the instructional curriculum of the professional schools. So far as I am aware, the first formal incorporation into a medical curriculum of structural biological knowledge based on electron microscopy anywhere in the world was initiated in the Anatomy Department at the University of Washington School of Medicine in Seattle in 1948.
Ultrastructural Alterations in Hela Cells Induced by Spider Venom
Authors: McClendon Dale E. , Morgan Paul N. , Soloff Bernard L. 
Published: June 2020

It has been observed that minute amounts of venom from the brown recluse spider, Loxosceles reclusa, are capable of producing cytotoxic changes in cultures of certain mammalian cells (Morgan and Felton, 1965). Since there is little available information concerning the effect of venoms on susceptible cells, we have attempted to characterize, at the electron microscope level, the cytotoxic changes produced by the venom of this spider.Cultures of human epithelial carcinoma cells, strain HeLa, were initiated on sterile, carbon coated coverslips contained in Leighton tubes. Each culture was seeded with approximately 1x105 cells contained in 1.5 ml of a modified Eagle's minimum essential growth medium prepared in Hank's balanced salt solution. Cultures were incubated at 36° C. for three days prior to the addition of venom. The venom was collected from female brown recluse spiders and diluted in sterile saline. Protein determinations on the venom-were made according to the spectrophotometric method of Waddell (1956). Approximately 10 μg venom protein per ml of fresh medium was added to each culture after discarding the old growth medium. Control cultures were treated similarly, except that no venom was added. All cultures were reincubated at 36° C.
Buffered Formalin for Primary Fixation and Preserving Tissue for a Long Time
Authors: Yamamoto I. , Rosario B. 
Published: June 2020

It is known that suitably buffered formaldehyde can be used as a killing agent and primary fixative for electron microscopy(Pease).We were interested in how long buffered formalin preserves tissue. Thus, in this study, an attempt was made to observe ultrastructure of surgical material fixed and stored in buffered formalin for a long time.Pieces of fresh tissues were, fixed in buffered formalin at 4°C for one hour, and then placed at room temparature for weeks and months without changing solution.Buffered formalin used was prepared as follows:A. “ reagent grade ” formalinB. 0.05 M Sorensen's phosphate buffer, pH 7.2-7.4 mix 1 part of A and 9 parts of B to make 10 % solution.Pieces of tissues were then minced and postfixed in 1 % osmic acid buffered with veronal acetate for two hours or more. Postfixed tissues were then embedded in an epoxy resin mixture through standard technique. Thin sections were stained with uranyl acetate followed by lead, and examined in a Hitachi 11C electron microscope.
Basement Membrane of Smooth Muscle Cell and Its Association With Elastic Tissue in Aorta
Authors: Yu S.Y. , Sun C.N. 
Published: June 2020

Organization and connection between smooth muscle cells and elastic tissues in aortas is not elucidated. Keech believed that the smooth muscle cells anchore on the elastic tissue. Among the fibers of the aortic connective tissue, there are collagen, elastic tissue and microfibril. This communication is to present evidence that the microfibrils which are derived from the basement membrane of the smooth muscle cells, play a role for connection between the smooth muscle cells and the elastic tissues.Thoracic aortas from new born rats were fixed with Dalton's chrom-osmium solution, embedded in Epon 812 and stained with uranyl acetate and lead citrate. Our previous work showed that the smooth muscle cell synthesized the elastic tissue during its differentiation prior to completing the process. At the actively synthesizing site of the cell, the basement membrane was replaced by numerous microfibrils (Fig. 1 MF). The microfibrils extended from the basement membrane toward the preformed elastic lamellae (EL), occasionally surrounded scallop-shaped elastic unit (EU).
Problems in Myogenesis Terminology in Electron Microscopy
Authors: Conen P.E. , Balis J.U. , Bell C.D. 
Published: June 2020

Myogenesis in man was studied using muscle from 19 fetuses of 8 to 16 weeks gestation which were processed with standard osmium-Epon or glutaraldehyde-osmium-Epon schedules and sections were stained in uranyl acetate and/or lead hydroxide. Particular emphasis was given during this study to presence of basement membrane and myofilaments as additional aids in classification of cell types present in developing muscle.Electron microscopy permits accurate identification of fibroblasts and early cells of muscle series and has been used in studies of myogenesis in chick, and rat. Light microscopy definitions for premyoblasts and myoblasts, and for myocytes at the myotube and muscle fiber stages of development are difficult to apply to electron microscopic studies without modification. For example the term myoblast was used differently by Tello, Katznelson and Boyd to designate a cell destined to become muscle but not recognizable as a muscle cell.
Quantitative Examination of the Myelinated Fibers in Electron Micrographs of the Cat’s Visual Cortex
Authors: Haug Herbert 
Published: June 2020

It is possible to measure the length of a linear tract with the aid of stereological methods. The myelinated fibers of the nervous system are such linear tracts. The myelinated fibers of the cerebral cortex have different directions, therefore it is impossible to measure their length directly with the light microscope. Furthermore some of them are very small and their diameters can only be measured in electron micrographs.The correctness of stereological measuring of the length of myelinated fibers has been proved by the aid of other methods (HAUG 1967). The subject of investigation was the comparison of the upper part of the griseum of cerebral cortex (layer I, II and III) and the album near the border of visual cortex. Both parts are different in quantity and thickness of their myelinated fibers. After fixation by perfusion with glutaral-dehyde-phosphatbuffer and a short postfixation with osmium-tetroxyde small blocks of both parts were embedded in Vestopal with a random orientation.
Scanning Electron Microscopy Using Cathodoluminescence
Authors: Pease R. F. W. , Hayes T. L. 
Published: June 2020

It is desirable to derive molecular information from many specimens with a resolution better than can be achieved with a light microscope. In the conventional electron microscope such information is usually only obtained indirectly by staining the specimen with a stain containing a heavy metal.In the scanning electron microscope (SEM), the optical focusing is independent of the contrast process; this allows a wide variety of contrast mechanisms e.g. secondary electrons emission which gives information of surface topography and voltage, and X ray emission which reveals atomic content.Some specimens emit light when bombarded with electrons. This process, cathodoluminescence, is characteristic of the molecular content of biological specimens and therefore we are investigating using this emitted light to build up scanning electron micrographs. Although similar information can be obtained using ultra violet fluoresence microscopy, the scanning electron technique offers the possibility of improved resolution since this is limited fundamentally by the electron probe diameter which can be 50Å or smaller.
Application of the Ussing Transport Chamber to the Study of Ultrastructure and Function in Injured Cells
Authors: Saladino Andrew J. , Trump Benjamin F. 
Published: June 2020

The Ussing transport chamber is a two compartment system separated by an intact epithelial layer. Manipulation and analysis of these compartments and epithelium provide electrophysiological, biochemical and morphological data concerning the partitioning cellular complex. Control over many environmental variables is facilitated. This chamber, therefore, provides a simple system for study of the alterations of morphology and function that follow specific injurious events.In the present studies the toad bladder was the partitioning cellular complex and inhibition of energy metabolism the specific injury. Incubated control preparations consisted of bladder halves incubated in a balanced salt solution and allowed to function over an extended time period (~15 hours) without exogenous substrate. Experimental preparations were treated with 10-3 M cyanide and 10-4 M iodoacetate for a similar period. The transepithelial potential difference was monitored continuously and tissue was removed for study by electron microscopy.
Fine Structure of Carotid Body: Normal and Anoxic Cats
Authors: Al-Lami Fadhil , Murray R.G. 
Published: June 2020

Although the fine structure of the carotid body has been described in several recent reports, uncertainties remain, and the morphological effects of anoxia on the carotid body cells of the cat have never been reported. We have, therefore, studied the fine structure of the carotid body both in normal and severely anoxic cats, and to test the specificity of the effects, have compared them with the effects on adrenal medulla, kidney, and liver of the same animals. Carotid bodies of 50 normal and 15 severely anoxic cats (9% oxygen in nitrogen) were studied. Glutaraldehyde followed by OsO4 fixations, Epon 812 embedding, and uranyl acetate and lead citrate staining, were the technics employed.We have called the two types of glomus cells enclosed and enclosing cells. They correspond to those previously designated as chemoreceptor and sustentacular cells respectively (1). The enclosed cells forming the vast majority, are irregular in shape with many processes and occasional peripheral densities (Fig. 1).
Fine Structure of the Connecting Piece of the Spermatozoon
Authors: Stefanini Mario , Zamboni Luciano 
Published: June 2020

Past studies have demonstrated that the connecting piece of the mammalian spermatozoon consists of several components; namely, the “proximal” centriole, the segmented columns, the fibrils of the axial filament complex, and mitochondria. Little is known, however, of the anatomical and functional relations which bind these structures together. This prompted us to investigate the structural organization of the connecting piece by means of tridimensional studies on thin sections of human and rabbit spermatozoa from testis and epididymis.The connecting piece has the shape of an inverted cone. At its base lies the proximal centriole which is inclined at an angle of about 45° to the long axis of the flagellum. The nine dense fibers of the flagellum are continuous with the segmented columns (Figs. 1 and 4) which form the wall of the connecting piece. Fusion of fibers 9, 1 and 2 on one side (Fig. 3), and 5 and 6 on the other induces formation of two major segmented elements and reduces to six the total number of columns. However, the nine original columns become reconstituted at the proximal end of the connecting piece where the fused elements of the major columns separate again.
Special Cutaneous Receptor Organs of Fish: Synaptic Structures of Eigenmannia
Authors: Szamier R. Bruce , Wachtel Allen W. 
Published: June 2020

Special cutaneous receptor organs of fresh-water weakly electric fish are grossly similar to other receptor organs of the acoustico-lateralis system, but differ in numerous cytological details. They are presumed to function as detectors of weak electric currents. Those of Eigenmannia are of two types that have been designated tuberous and ampullary receptor organs. Parts of the lateral and basal surfaces of the receptor cells are in contact with accessory cells. A single relatively large, almost spherical, nerve ending is inserted between the basal end of each receptor cell and the subjacent accessory cell, lying within a hemispherical concavity in the base of the receptor cell.The presumed synaptic areas between each receptor cell and the nerve ending associated with it are not contiguous, but are morphologically discrete structures, separated by nonsynaptic areas of membrane (Fig. 1). Approximately thirty synaptic areas are found on each receptor cell in both kinds of organs. The surface contours of the apposed cell membranes are irregular in the nonsynaptic areas, and hence the extracellular space is variable in width. In the synaptic areas the membranes of both cells appear slightly thickened (Fig. 2), and are separated by a constant gap of about 200 Å. Fine fibrillar material spans the synaptic gap.
A Slotted Electrode Stigmator for Correction of Short Focal Length Objectives
Authors: Reisner J. H. , Schuler J.J 
Published: June 2020

One of the difficulties which must be overcome in the design of objective lens stigmators is that they necessarily take up space where it is most precious, in the vicinity of the specimen. The space following the specimen is needed for the contrast aperture while the space between magnetic poles in the gap is required for stage mechanism. To go appreciably below the objective back focal plane to position stigmators subjects the image to possible image distortion when correction is large. A further problem is caused by the trend to shorter objective focal lengths, e.g., 1.5 mm, thus further reducing the space available for the stigmator.To adapt the electrostatic stigmator to these physical restraints, a design has been completed which is only 0.75 mm thick and has a free bore diameter of the same size. Its sensitivity is 0.1 micron/volt with 100 kV electrons. The overall diameter is uncritical and may be adapted to the physical requirements of the system. It should be possible to make stigmators of 3 mm thickness with a simple reduction of critical dimensions (thickness and slot width).
Electron Microscopic Study of Quench-Hardening in Aluminum
Authors: Mori T. , Meshii M. 
Published: June 2020

Fundamentals of the morphology of plastic deformation in quench-hardened aluminum single crystals were studied. The study confirmed the correspondence of the loop-depleted zone (channeling) to the slip bands which was previously reported in polycrystalline specimens. Furthermore, kinetics of formation and growth of the slip bands were studied as a function of plastic strain.Single crystals of 99.999% aluminum, grown by the strain anneal method from sheets of 0.8 mm. thickness, were quenched from 640°C into brine at -40°C and aged for 2 hours at 60°C. The density of vacancy loops, approximately 170 Å in diameter, which was produced by this quenching and aging treatment is about 1015/cm3. Tensile tests were performed with an Instrom machine with the strain rate of 2 x 10-4/sec.
Identification of BetaSiC Precipitate Formed in p-Type Silicon Single Crystals during Annealing
Authors: Tufts Charles F. 
Published: June 2020

Using high energy reflection electron diffraction, Newman (1) identified a precipitate of PSiC structure below the surface of silicon single crystals annealed in the range of 1000°-1250°C. This structure is cubic with SG: TD2 and ao = 4.358 Å. Most crystals were in the size range: 0.3-0.7μ. PSiC was not detected unless the silicon contained both aluminum and an n-type doping impurity such as phosphorus. Dislocation densities to 3 × 104/cm2 were present.Similar studies at this Laboratory showed that βSiC structure could be detected in silicon single crystals without the presence of aluminum and n-type impurities. In our work, accelerating voltage for electron diffraction was 100 kV; a double condenser was the only lens; camera length was 50 cm; direct beam spot size was 35-50μ at the plate plane. Specimens were p-type (111) Si wafers grown by Czochralski methods; resistivities were 50-60 ohm cm; boron was the major impurity.
Epitaxial Growth of Cadmium Sulfide Films Evaporated Upon Mica
Authors: Shimaoka G. , Walch A. S. 
Published: June 2020

It has been reported that thin cadmium sulfide films evaporated onto a glass substrate show strong preferred orientation with the (0001) plane parallel to the substrate surface. Escoffery has reported highly oriented CdS crystals evaporated onto mica heated at 250°C. The purpose of the present experiment is to study the structure and orientation of thin CdS films evaporated onto a mica substrate as a function of the substrate temperature and to find the temperature of optimum epitaxial growth.Cadmium sulfide was evaporated onto a freshly cleaved mica surface heated at various temperatures between 25° and 500°C in a vacuum of ∼ 1 × 10−4 torr. Average thickness of the evaporated films was about 500Å. The evaporated specimens were divided into two parts. The first part was examined by reflection electron diffraction for several different azimuthal positions of the deposits on the mica surface. The other part was used for direct transmission electron microscopy.
Secondary Electron Detection in a Field Emission Scanning Microscope
Authors: Crewe A. V. , Isaacson M. , Johnson D. 
Published: June 2020

A scanning microscope using only a field emission gun, without auxiliary lenses, has been described elsewhere. It has been shown capable of 100 Å resolution using transmitted electrons with a beam current of 10-10 amps. Detectors have now been installed to test its performance using secondary electrons.Detection of secondary electrons in this microscope differs in some ways from detection in a conventional scanning microscope. First, the operating vacuum of 10-9 to 10-10 Torr places restrictions on detector construction and materials. Second, the high beam current reduces the noise restrictions on detector and amplifier. Third, the large possible working distance (up to ∿ 8 cm for a beam diameter of 200 Å) increases flexibility in the mechanical design.