bluuebunny/crossref_metadata_2025_split huggingface dataset:
Visualization of the Platelet-Plasma Interface
Authors: Brindley D. C. , McGill M. 
Published: June 2020

Morphological and cytochemical studies of platelets have reported a surface coat, or glycocalyx, external to the plasma membrane (1). Biochemical analyses have likewise confirmed the highly adsorptive properties of platelets as transporters of coagulation factors (2). However, visualization of the platelet membrane by conventional EM procedures does not reflect this special relationship between the platelet and its plasma environment. By the routine method of alcohol-propylene oxide dehydration for Epon embedding, the lipid bilayer nature of the platelet membrane appears similar to other blood cells (Fig. 1). A new rapid embedding technique using dimethoxypropane (DMP) as dehydrating agent (13) has permitted ultrastructural analyses of the surface features of the platelet-plasma interface.Aliquots of human or rabbit platelet-rich plasma (PRP) were added to equal volumes of 6% glutaraldehyde in Millonig's buffer at 37° for 45 minutes, rinsed in buffer and postfixed in 1% osmium in Millonig's buffer for 45 minutes.
Spontaneous Cataract in Nude Athymic Mice
Authors: Bradley Ronald H. , Berk R. S. , Hazlett L. D. 
Published: June 2020

The nude mouse is a hairless mutant (homozygous for the mutation nude, nu/nu), which is born lacking a thymus and possesses a severe defect in cellular immunity. Spontaneous unilateral cataractous lesions were noted (during ocular examination using a stereomicroscope at 40X) in 14 of a series of 60 animals (20%). This transmission and scanning microscopic study characterizes the morphology of this cataract and contrasts these data with normal nude mouse lens.All animals were sacrificed by an ether overdose. Eyes were enucleated and immersed in a mixed fixative (1% osmium tetroxide and 6% glutaraldehyde in Sorenson's phosphate buffer pH 7.4 at 0-4°C) for 3 hours, dehydrated in graded ethanols and embedded in Epon-Araldite for transmission microscopy. Specimens for scanning electron microscopy were fixed similarly, dehydrated in graded ethanols, then to graded changes of Freon 113 and ethanol to 100% Freon 113 and critically point dried in a Bomar critical point dryer using Freon 13 as the transition fluid.
Ultrastructural Studies of Acute Rheumatic Valvulitis
Authors: Siew S. 
Published: June 2020

The advent of cardiac surgery has accorded the opportunity of obtaining fresh human tissue suitable for electron microscopy. The percentage of acute rheumatic lesions in such material is understandably small and there has been comparatively little progress with the ultrastructural investigation of this stage of the disease. This report presents the transmission and scanning electron microscopic findings of 3 cardiac valves: a mitral, a tricuspid and an aortic, which had been resected on the basis of the clinical diagnoses of mitral stenosis, tricuspid stenosis and aortic insufficiency, respectively. Gross and histological examination showed the classical features of acute and chronic rheumatic valvulitis.Transmission electron microscopy was performed on the valves and on the related structures of the atrio-ventricu1ar valve mechanism, the chordae tendineae and the papillary muscles. The valves were thickened and showed the presence of abundant collagen, some elastic tissue and foci of calcification.
Hepatic Ultrastructure in Methotrexate Treated Psoriatic Patients
Authors: Horvath E. , Kovacs K. , Ross R. C. , Kerenyi N. A. , Saibil F. G. 
Published: June 2020

Fifty liver biopsies of psoriatic patients treated with methotrexate, a folic acid antagonist, for a period from a few weeks up to 15 years have been studied. Liver tissue has been obtained by percutaneous biopsy with a Menghini needle and prepared for electron microscopy by using conventional techniques.In the hepatocytes, profound changes have been revealed in four areas: nucleus, mitochondria, ectoplasmic zone-cell membrane and desmosomes. The nuclei showed reduced electron opacity and almost complete absence of heterochromatin. Cytoplasmic invaginations and glycogen inclusions were common. Mitochondrial pleomorphism, paracrystalline inclusions and giant mitochondria were prominent findings. Compartmentalization, fission and division of mitochondria were also noted. Sequestration of mitochondria via development of cytosegresomes was observed in several cases. Detachment of desmosomes was a conspicuous finding in 25 of 50 biopsies obtained from methotrexate-treated psoriatics. In these livers many or practically all membrane sites with desmosomal specialization appeared to be pulled apart.
Ultrastructural Study of Peroxisomes in Human Hepatocytes of a Chronic Alcoholic
Authors: Lim B.S. 
Published: June 2020

Peroxisomes in normal human hepatocytes are catalase-containing rounded or oval organelles with an average diameter of 0.63 μm (l). They are usually surrounded by single tripartite membranes. Their presence can be easily demonstrated by the use of 3,3' diaminobenzidine (DAB) stain in the presence of H202 (2). This paper represents an ultrastructural study of peroxisomes in tne liver biopsy of an alcoholic patient with preoperative diagnosis of fatty infiltration.Biopsy tissues were fixed in 5% glutaraldehyde in 0.1 M phosphate buffer (pH 7.4), postfixed in 1% OsO4 and embedded in epoxy resin. Thin sections were stained with lead citrate and uranyl acetate and examined with a Zeiss EM 9 S-2.Light microscopic study of the liver biopsy reveals an intact hepatic architecture. The hepatocytes appear slightly edematous and possess many eosinophilic granules.Electron microscopy (Fig l) reveals that there is a marked increase in the number of randomly distributed peroxisomes in alcoholic human hepatocytes.
Heterogeneity of Size and Distribution of Intramembrane Particles in the Plasma Membrane of Yeast
Authors: Keyhani E. 
Published: June 2020

The matrix of biological membranes consists of a lipid bilayer into which proteins or protein aggregates are intercalated. Freeze-fracture techni- ques permit these proteins, perhaps in association with lipids, to be visualized in the hydrophobic regions of the membrane. Thus, numerous intramembrane particles (IMP) have been found on the fracture faces of membranes from a wide variety of cells (1-3). A recognized property of IMP is their tendency to form aggregates in response to changes in experi- mental conditions (4,5), perhaps as a result of translational diffusion through the viscous plane of the membrane. The purpose of this communica- tion is to describe the distribution and size of IMP in the plasma membrane of yeast (Candida utilis).Yeast cells (ATCC 8205) were grown in synthetic medium (6), and then harvested after 16 hours of culture, and washed twice in distilled water. Cell pellets were suspended in growth medium supplemented with 30% glycerol and incubated for 30 minutes at 0°C, centrifuged, and prepared for freeze-fracture, as described earlier (2,3).
Fine Structure of Oogenesis in the Snail Tarebia Granifera (Melaniidae)
Authors: Matthes Michael T. , Blystone Robert V. 
Published: June 2020

The ovary of the fresh-water snail, Tarebia granifera, is found in the caudal upper whorls of the shell. Careful dissection was required to separate the ovary from the digestive gland which shared a common epithelial covering with the ovary. The ovarian tissue was fixed in sodium cacodylate buffered 3% glutaraldehyde, post-fixed in 1% osmium tetroxide, en bloc stained with 0.5% uranyl acetate, dehydrated, and embedded in Epon-Araldite plastic.This study indicated that oocytes of T. granifera were found only in prophase stages of maturation along the length of the ovarian tube. A similar observation has been documented for the closely related snail Melanoides. The T. granifera oocytes were situated in the ovary in such a way that the immature early prophase oocytes were found near the outer ovarian wall and the more mature late prophase oocytes were seen developing toward the center of the ovarian tubular structure.
Ultrastructure of the Parotid Gland of the Nine-Banded Armadillo
Authors: Ruby J. R. 
Published: June 2020

Parotid glands were obtained from five adult (four male and one female) armadillos (Dasypus novemcinctus) which were perfusion-fixed. The glands were located in a position similar to that of most mammals. They extended interiorly to the anterior portion of the submandibular gland.In the light microscope, it was noted that the acini were relatively small and stained strongly positive with the periodic acid-Schiff (PAS) and alcian blue techniques, confirming the earlier results of Shackleford (1). Based on these qualities and other structural criteria, these cells have been classified as seromucous (2). The duct system was well developed. There were numerous intercalated ducts and intralobular striated ducts. The striated duct cells contained large amounts of PAS-positive substance.Thin sections revealed that the acinar cells were pyramidal in shape and contained a basally placed, slightly flattened nucleus (Fig. 1). The rough endoplasmic reticulum was also at the base of the cell.
Incorporation of the automated tissue processing system in biological electron microscopy—a further critical evaluation
Authors: Aihara Kaoru , Suzuki Katsuya , Hirohata Yasuhisa , Yajima Mioko , Yajima Gonpachi , Hata Toshio , Goro Asano , Matsumoto Keiko , Kurokawa Taneomi , Takahashi Kikuo , Mori Hidekatsu , Tsuzuki Takashi 
Published: June 2020

Objective: In reviewing the attempt to incorporate the automated tissue processing system in the diagnostic or clinical electron microscopic investigation to relief the paintaking harmfull manipulation of the chemicals and for the safety management of the laboratory persons, the authors inclined to make a few introductory remarks on this matter. one has been developed by Dr.Norris and Dr.Banfield in the U.S.A.,N.I,H.group, and the other has been developed by our group which is hitherto reported and designated as Aihara Processor. The present communication is dealing with the further development of the automated processing with emphasis on its versatility in the efficient laboratory management. Historically: i)Norris processor ii)Benjamin processor and iii)Aihara processors are developed and currently be available for use.Mechanical principle of the automated tissue processing device: The basic principle is adapted from the automated tissueprocessing device from the light microscopic tissue preparation. The prototype is basically adapted from from the rolling type turntable which accomodate the specimen holder which is cover by plastic dome in entirety.
Contamination of thin sections, cause and elimination
Authors: Mollenhauer Hilton H. , James Morré D. 
Published: June 2020

Contamination of thin sections is a problem that has undoubtedly been experienced by most, if not all, electron microscopists. By section contamination, we refer to any extraneous material in, or on, a thin section. Section contamination is not only a nuisance to the investigator but a serious waste of time and a possible cause of image misinterpretation. Section contamination usually appears sporatically and can often be solved by changes in the fixation, embedding, or staining procedures. However, the true cause of section contamination is only occasionally identified. Four types of section contamination are described in this report along with potential causes and remedies.SURFACE CONTAMINATION is defined as any extraneous material on the surface of a section. Surface contamination occurs during the poststaining procedure and is perhaps the most common and easiest to recognize of the four section contaminations being discussed. Sections look "dirty" and the contaminating particles may be both large and dense.
Electron microscopic analysis of objects in light microscopic sections
Authors: Maunsbach Arvid B. 
Published: June 2020

Structural studies in experimental biology or in pathology are frequently extended from the light to the electron microscopic level. This is often done by cutting both semithin (about 1 μm) and thin sections from the same tissue block after embedding for electron microscopy. However, in many studies it would be of great value to analyse the same structure both by light and electron microscopy, i.e. to be able to study by electron microscopy an object which is first detected by light microscopy in a semithin section. To achieve this, a method has been developed by which ultrathin sections are cut directly from the semithin section containing the object of interest.Semithin sections, about 1 μ in thickness, are cut from Epon or Vestopal embedded tissue. The sections are placed on ordinary glass slides and stained with toluidine blue. The sections are studied in the light microscope without a cover glass or mounted in water.
Localization of pancreatic enzymes in ultrathin frozen sections stained with metal labeled antibody
Authors: Yasuda Kenjiro 
Published: June 2020

Localization of amylase,chymotrypsinogen and trypsinogen in pancreas was demonstrated by Yasuda and Coons (1966), by using fluorescent antibody method. These enzymes were naturally found in the zymogen granules. Among them, amylase showed a diffuse localization around the nucleus, in addition to the zymogen granules. Using ferritin antibody method, scattered ferritin granules were also found around the Golgi area (Yasuda et al.,1967). The recent advance in the tissue preparation enables the antigen to be localized in the ultrathin frozen sections, by applying the labeled antibodies onto the sections instead of staining the tissue en bloc.The present study deals with the comparison of the localization of amylase and lipase demonstrated by applying the bismuth-labeled, peroxidase-labeled and ferritin-labeled antibody methods on the ultrathin frozen sections of pancreas, and on the blocks of the same tissue.
A new technique for preparation of beverage samples for asbestos measurement by electron microscopy
Authors: Chatfield E.J. 
Published: June 2020

Quantitative evidence on the health risks associated with gastrointestinal exposure to asbestos fibres is somewhat deficient, although an excess incidence of gastrointestinal carcinoma has been demonstrated in the case of occupational exposure. The use of chrysotile asbestos as a filter medium for clarification or sterilization of some beverages has thus led to a requirement for analytical techniques for fibre concentration measurement in these liquids.A technique has been described in which the liquid is passed through a membrane filter; this is then ashed and the residue redispersed ultrasonically in fibre-free water. A few microlitres of the resulting suspension are evaporated to dryness on a carbon-coated TEM grid, and fibres are counted on a few grid openings. The high organic content of some beverages, however, often prevents filtration of an adequate volume through a membrane filter of a realistic pore size. Pectins, yeast cells and bacteria are the principal components responsible.
X-ray microanalysis of frozen-hydrated bulk biological specimens: fundamental considerations
Authors: Low W.C. , Burgio P.A. , Allard L.F. , BeMent S.L. , Bigelow W.C. , Lawrence M. 
Published: June 2020

X-ray microanalysis and scanning electron microscopy used in conjunction with cold-stage techniques to examine frozen-hydrated bulk biological tissue is a promising method to determine the concentration and distribution of diffusible elements which are typically distorted by conventional techniques of biological tissue fixation. The proper application of this method, however, requires an understanding of the freezing and sublimation processes in bulk biological specimens, and the interaction of the electron beam with the bulk specimen in the frozen-hydrated state. These factors have been evaluated and are discussed below.One of the fundamental considerations in the examination of cryofixed bulk tissue is the formation of exogenous and endogenous ice crystals within the specimen or upon the surface of the specimen which can lead to tissue distortion and ion translocation. Techniques to minimize the exposure of the specimen to atmospheric conditions and to eleminate the formation of exogenous ice crystals have been developed by Burgio et al. (1978a), and Echlin and Moreton (1974).
Electron microscope autoradiography of isolated molecules
Authors: Bouteille M. , Delain E. , Angelier N. 
Published: June 2020

The LIGOP method of electron microscope autoradiography which consists in a combination of coating Ilford emulsion with the loop technique and developing with gold latensification and phenidon has proved to provide small, compact developed silver grains with high efficiency.This has made it possible to use this technique with very small materials such as isolated molecules of molecular complexes.The method was assayed first with 3H-Thymidine labelled T7 phages DNA molecule with 630,000 cpm/μg specific activity (fig. 1). The molecules were spread using the adsorption technique constrasted by rotatory shadowing with platinum and then subjected to autoradiography. The Labelling was sufficient to obtain quantitative data in which the spread molecules were considered as a material comparable to a “hot line”. The efficiency (45%) and the HD value (1600 Å) were calculated.The method was also applied to transcription units of pleurodeles oocytes nucleoli (fig. 2) labelled in vitro with 3H-Uridine.
Structural similarity of ribosomes from E. coli and A. salina
Authors: Boublik M. , Wydro R.M. , Hellmann W. , Jenkins F. 
Published: June 2020

Ribosomes are ribonucleoprotein particles necessary for processing the genetic information of mRNA into proteins. Analogy in composition and function of ribosomes from diverse species, established by biochemical and biological assays, implies their structural similarity. Direct evidence obtained by electron microscopy seems to be of increasing relevance in understanding the structure of ribosomes and the mechanism of their role in protein synthesis.The extent of the structural homology between prokaryotic and eukaryotic ribosomes has been studied on ribosomes of Escherichia coli (E.c.) and Artemia salina (A.s.). Despite the established differences in size and in the amount and proportion of ribosomal proteins and RNAs both types of ribosomes show an overall similarity. The monosomes (stained with 0.5% aqueous uranyl acetate and deposited on a fine carbon support) appear in the electron micrographs as round particles with a diameter of approximately 225Å for the 70S E.c. (Fig. 1) and 260Å for the 80S A.s. monosome (Fig. 2).
Contributions to the mechanisms of mitosis and roles of cytoplasmic microtubules from ultrastructural analyses of fungi
Authors: Brent Heath I. 
Published: June 2020

Detailed ultrastructural analysis of fungal mitotic systems and cytoplasmic microtubules might be expected to contribute to a number of areas of general interest in addition to the direct application to the organisms of study. These areas include possibly fundamental general mechanisms of mitosis; evolution of mitosis; phylogeny of organisms; mechanisms of organelle motility and positioning; characterization of cellular aspects of microtubule properties and polymerization control features. This communication is intended to outline our current research results relating to selected parts of the above questions.Mitosis in the oomycetes Saprolegnia and Thraustotheca has been described previously. These papers described simple kinetochores and showed that the kineto- chores could probably be used as markers for the poorly defined chromosomes. Kineto- chore counts from serially sectioned prophase mitotic nuclei show that kinetochore replication precedes centriole replication to yield a single hemispherical array containing approximately the 4 n number of kinetochore microtubules diverging from the centriole associated "pocket" region of the nuclear envelope (Fig. 1).
Cell surface topography in adhesion and detachment
Authors: Allen T.D. 
Published: June 2020

The effects of trypsin and EGTA were investigated in parallel on two epithelial cell lines: a normal rat-liver parenchyma line (Fig. 1) and a spontaneously transformed line which had been subcloned in soft agar. The basic ultrastructural differences between these two cell lines has already been reported; briefly, the transformed cells, although typically epithelial in morphology, lack the well ordered microtubular and microfilamentous organisation of the normal cells but exhibit a marked increase in the number of surface microvilli.The reaction of each cell line to trypsination was broadly similar between the normal and transformed cell lines, with the transformed cells rounding up and detaching at a slightly quicker rate than the normals. In both cases the central region of the cell became domed with the peripheral cytoplasm being withdrawn in a thin sheet, some of which remained extended in short retraction fibrils (Fig. 2). Collection of the detached cells (after fixation in suspension) by aspiration onto silver filters showed the increased density of microvilli on the transformed cells to be maintained.
Unique association of three new type B retrovirus isolates with kinetochores and centrioles of the host cell
Authors: Heine U. I. , Todaro G. J. 
Published: June 2020

Three new virus isolates, M432, M832 and M960, obtained from the Southeast Asian mouse have been characterized morphologically in ultrathin sections and by negative staining with respect to their composition and intracellular assembly. The three isolates share certain morphological properties with the murine mammary tumor virus, a retrovirus of type B; yet previous investigations illustrated that they can readily be distinguished both from each other and from known retroviruses of the mouse, both of type B and C, by their RNA genome protein composition and reverse transcriptase activity.As illustrated in ultrathin sections (Fig. 1), the mature virions of about 100-120 nm in diameter contain a centrally located, electron dense nucleoid, a thin intermediate shell and an enveloping membrane derived from the plasma membrane. In negatively stained preparations (Fig. 1), the virions exhibit on their surface spikes which are best resolved on the isolate M432 and resemble the spikes present on the surface of retroviruses of type B.
The plasma membrane of pityrosporum has natural markers to show how the cell grows
Authors: Takeo Kanji , Nakai Ei-Ichi 
Published: June 2020

Pityrosporum is a lipophilic yeast containing the causative agent of tinea versicolor, and has spiral grooves on the inner surface of the cell wall and the plasma membrane. Detailed studies on the plasma membrane of this organism revealed the existence of asymmetry around the plasma membrane, peculiar mode of the growth of this organism, mode of spiral groove formation, and a possible mechanism of groove formation. One strain each of Pityrosporum orbiculare and P. pachydermatis and ten strains of P. ovale were grown on a potato yeast extract agar, supplemented with 1% olive oil at 27-37°C for 1-20 days. Cultures were directly transferred to the specimen holder of the freeze-etching apparatus without no pretreatment. 40% glycerol was added before cooling.All the strains tested of the genus Pityrosporum had only left-handed spiral grooves of the plasma membrane. Left-handedness of the spiral grooves of Pityrosporum was confirmed by scanning electron microscopy which occasionally revealed left-handed spiral grooves on the outer surface of the wall.