bluuebunny/crossref_metadata_2025_split huggingface dataset:
An Ultrastructural Study of the Female Reproductive Tract of Campoletis sonorensis (Hymenoptera)
Authors: Norton W. N. , Vinson S. B. , Thurston E. L. 
Published: June 2020

The immune system of insects, which combats metazoan organisms, functions through haemocytic encapsulation. It is still unclear as to the exact mechanism by which insect parasitoids successfully escape encapsulation while within their habitual host; however, it is apparent that the nature of the parasitoid egg surface is of importance.An ultrastructural study of the female reproductive tract of the ichneumonid parasitoid, Campoletis sonorensis, reveals that oogenesis seems to occur in a manner similar to that of other polytrophic insects. As the developing oocyte passes down the ovariole, it receives nutrients and cytoplasmic organelles from accompanying nurse cells. Follicular cells also exhibit a close relationship with the oocyte (Fig. 1) and a re considered essential for vitelline and chorion synthesis.
Bacterial-Mucosal Cell Junctional Complexes
Authors: Wagner Roger C. 
Published: June 2020

Bacteria exhibit the ability to adhere to the apical surfaces of intestinal mucosal cells. These attachments either precede invasion of the intestinal wall by the bacteria with accompanying inflammation and degeneration of the mucosa or represent permanent anchoring sites where the bacteria never totally penetrate the mucosal cells.Endemic gram negative bacteria were found attached to the surface of mucosal cells lining the walls of crypts in the rat colon. The bacteria did not intrude deeper than 0.5 urn into the mucosal cells and no degenerative alterations were detectable in the mucosal lining.
Fine Structural Studies on the Scolex of Hymenolepis diminuta (Cestoda)
Authors: Specian R. D. , Allison V. F. , Ubelaker J. E. 
Published: June 2020

Although the scolex is the major area of contact between a cestode and its host, most fine structural studies have concentrated on the rest of the body. Davey and Breckenridge postulated, from histochemical data, that neurosecretory cells were present in the scolex of Hymenolepis diminuta. Such cells have been suggested to function in affecting growth and maturation of the strobila. Since a previous study by Rothman failed to determine such cells, the present study was undertaken.Specimens were collected from previously infected laboratory rats, fixed in paraformaldehyde, post-fixed in osmium tetroxide and embedded in Maraglas. Sections were examined on the Hitachi HU11B-2 transmission electron microscope.
Neural Fold Fusion in Xenopus Laevis Embryos
Authors: Mak Linda L. 
Published: June 2020

A morphological study of neural fold fusion in neurulae of the African Clawed Toad Xenopus laevis was undertaken. Segments of neural folds were dissected from embryos at Nieuwkoop and Faber stages 18 (neural groove), 19 (neural fold fusion) and 20 (neural tube) and fixed for electron microscopy.Cells from specimens in the prefusion stage exhibited much vesicular activity, especially those lining the neural groove. In certain instances the vesicles were open, extruding organelles and cytoplasm into the neural groove. The membranous projections of these opened vesicles protruded into the extraembryonic space. Vesicles (v, Fig. 1) were arranged in rows below the surfaces of cells lying along the neural groove. Some vesicles appeared to coalesce to form larger ones.
Mini-Scanning Electron Miscroscope Concept
Authors: Evins Donald J. , Engle Robert J. 
Published: June 2020

The scanning electron microscope has already established itself as one of the most useful instrument developments in recent years. The SEM provides 20 times greater useful magnifications and up to 500 times greater depth of-field than the best optical microscopes. Until the introduction of the Mini-SEM concept, the cost and complexity of SEM's has limited their use primarily to large research oriented laboratories.Design features, specifications, and operational characteristics will be reviewed. The Mini-Rapid Scan with resolution of 750Å will be described, along with the Mini-SEM with resolution of 150 to 200Å. Both of these are table top scanning electron microscopes. Various specimen stage options will be illustrated. Other accessories extending the SEM's versatility will be described, such as the energy dispersive x-ray system
S. E. M. Observations of Limestone Pore Space Replicas
Authors: Becher J. W. 
Published: June 2020

Pore geometry in carbonate rocks is of interest to petroleum geologists because it reflects the complex diagenetic changes that may create or destroy porosity. The size distribution of pore throats (restrictions in the continuous maze of pore channels) is a major parameter controlling hydrocarbon migration through water-wet rocks.Pore space replicas (plastic casts of pore space with the mineral material removed) have decided advantages over actual rock material for pore space observations. The replication of a limestone with 10 percent porosity will yield a plastic replica with 90 percent porosity.
Effect of Shock Loading on the Microstructure of Uniloy 326
Authors: Staudhammer K. P. , Murr L. E. 
Published: June 2020

The effect of shock loading on a variety of steels has been reviewed recently by Leslie. It is generally observed that significant changes in microstructure and microhardness are produced by explosive shock deformation. While the effect of shock loading on austenitic, ferritic, martensitic, and pearlitic structures has been investigated, there have been no systematic studies of the shock-loading of microduplex structures.In the current investigation, the shock-loading response of millrolled and heat-treated Uniloy 326 (thickness 60 mil) having a residual grain size of 1 to 2μ before shock loading was studied. Uniloy 326 is a two phase (microduplex) alloy consisting of 30% austenite (γ) in a ferrite (α) matrix; with the composition.3% Ti, 1% Mn, .6% Si,.05% C, 6% Ni, 26% Cr, balance Fe.
Observations of the Microstructure of WC-Co Cemented Carbides
Authors: Kimmel E. R. , Scheithauer W. 
Published: June 2020

Cemented carbides (hard metals) of the WC-Co type generally consist of two phases: WC, the major phase, and a Co-rich binder phase. The two alloys studied in this investigation were WC-6w/OCo and WC-13w/OCo. In production of these alloys, a ball milled mixture of WC powder and Co powder is die compacted and subsequently sintered at about 1400°C. This condition constitutes liquid phase sintering and results in a fully densified material.The work was undertaken to determine the feasibility of studying microstructures of hard metals using thin foils prepared by ion-beam thinning. Attempts at producing thin foils by electrolytic thinning have met with limited success due to non uniform thinning of the two phases. In contrast, we found that ion-beam thinning easily produced thin foils having relatively large and uniformly thin areas.
Ultrastructural Features of Leydig Cell Hyperplasia Due to an hCG-Producing Testicular Tumor
Authors: Asa S. L. , Bayley T. A. , Horvath E. , Kovacs K. 
Published: June 2020

Leydig cell clusters in the adult human testis are known to enlarge during chronic stimulation with excess LH as in Klinefelter's syndrome or following administration of exogenous human chorionic gonadotropin (hCG). However, the ultrastructural features of this hyperplasia, to our knowledge, have not been reported in association with testicular neoplasms producing hCG.We report the case of a 21-year-old man who sought medical attention because of gynecomastia. Laboratory investigation revealed a marked increase in serum hCG and elevated a-fetoprotein. A testicular mass was palpable on examination and the patient underwent orchiectomy.
Selective Destruction of Mitochondria by Aziridinylbenzoquinone (AZQ)
Authors: Greenwood M.A. , Smith B.H. , Cooke C. , Robinson A. , Komblith P.L. , Cummins C. 
Published: June 2020

Aziridinylbenzoquinone (AZQ or 2, 4-diaziridinyl-3, 6-bis-carboethoxyamino-1, 4-benzoquinone, NSC No. 182986) is a new chemotherapy agent characterized by lipid solubility, high cerebrospinal fluid penetrance and potential as an antiglioma agent.In our laboratory the effects of AZO on 20 human central nervous system glioma-derived tumor cell lines in culture have been studied utilizing both in vitro solid phase and aqueous microcytotoxicity assays. In these in vitro assays a test concentration range over 3 log units (0.1 to 100 μg/ml AZQ) has indicated varying sensitivity of glioma-derived tumor cell lines. Concentrations sufficient to produce greater than 30 percent cytotoxicity ranged from 1.0 yg/ml to 50 yg/ml, being different for each tumor line tested.
Granular Cell Tumor (Myoblastoma) of RAT Brain
Authors: White Yvonne , Sheldon Winslow , Hoage Terrell , West Robert 
Published: June 2020

Granular cell myoblastoma is a rare tumor of which the nature and origin has been controversial. The cytogenesis of this tumor has been suggested as a neoplastic derivation from adult or embryonic muscle tissue, a histiocytic storage phenomenon, of neural origin and as a neoplasm derived from Schwann cells.This report presents the ultrastructure of a spontaneously occurring granular cell tumor from the brain of a 22 month old female Sprague- Dawley rat. Gross examination revealed an oval, gray external mass 3x4 mm in size and located on the cerebellar dorsal surface. This tumor was connected by a narrow stalk to a tumor mass located in the molecular layer of the cerebellum. The external tumor and the stalk were excised for electron microscopy (EM) and the remaining tumor mass, brain, and stalk were processed for light microscopy (LM).
Electron Microscopy in Materials Science
Authors: Thomas Gareth 
Published: June 2020

The materials scientist is concerned with relating microstructure and properties. In crystals, most of the important imperfections can only be observed by transmission through thin foils (T.E.M.), first accomplished by Heidenreich in 1949. The truly amazing growth of T.E.M. is due mainly to three factors: a) improvements in microscopes, b) techniques for foil preparation, c) interpretation of images using electron diffraction contrast theory. Almost all of T.E.M. has developed since 1955 as a result of the above factors.The following is a listing of some of the applications of Electron Microscopy.a) Observation and identification of lattice defects (dislocations, faults, small defect clusters, etc.).b) Crystallographic data from electron diffraction.c) Surface investigations, replication, reflection and scanning microscopy; fractography.d) Qualitative chemical analysis of characteristic x-rays emitted by the foil.e) Energy analyses for contrast and for identifying elements (by scanning microscopy also).f) In situ investigations of crystal growth, epitaxy.g) Examination of specimens at different temperatures; deformation, bombardment in situ.
Exfoliative Cytology of the Lung Alveolus: Preliminary Electron Microscopic Observations on Cells Obtained In Vivo From Human Lungs
Authors: Ladman A. J. , Pratt Susan A. , Finley T. N. 
Published: June 2020

Earlier studies using endobronchial lavage of segments of dog lung have established the feasibility of this procedure to assess the physico-chemical nature of lipids lining the lung alveolus and to characterize the functional cytology of cells returned in the effluent fluid. These techniques have been tried in selected normal humans and patients with lung disease in order to establish base-lines of presumed normal values for future biochemical and morphological analyses. The present report illustrates some of the morphological features of cells recovered from “normal” volunteers, both non-smokers and smokers, and a patient having clinically diagnosed rheumatoid lung disease.Bronchopulmonary segments of human lung were intubated with a 19F Metras retention catheter after appropriate local anesthesia of the upper airway. The cuffed tip was inflated and three 100 ml aliquots of normal saline were lavaged gently in and out through the catheter. The returned fluid was spun at 27,000 xG for 20 minutes at 0°C and the cellular sediment of the lavage was fixed in cold glutaraldehyde and post-fixed in osmium tetroxide. Following rapid dehydration in ethanol, the cells were embedded in Epon 812.
Silver Staining of Pancreatic Islets as Revealed by Electron Microscopy
Authors: Misugi Kazuaki , Misugi Nobuko , Yamada Hiroshi 
Published: June 2020

The authors had described the fine structure of a type of pancreatic islet cell, which appeared different from typical alpha and beta cells, and tentatively considered that this third type of granular cell probably represents the D cell (Figure 1).Since silver staining has been widely used to differentiate different types of pancreatic islet cells by light microscopy, an attempt to examine this staining reaction at the electron microscopic level was made.Material and Method: Surgically removed specimens from three infants who suffered from severe hypoglycemia were used. The specimens were fixed and preserved in 20% neutral formalin. Frozen sections, 30 to 40 micron thick, were prepared and they were stained by Bielschowsky's method as modified by Suzuki (2). The stained sections were examined under a microscope and islet tissues were isolated. They were fixed in 1% osmium tetroxide in phosphate buffer for one hour and embedded in Epon 812 following dehydration through a series of alcohols and propylene oxide.
Transformation of Myoepithelial Cells into Epithelial Cells in Pregnancy
Authors: Murad T. M. , von Haam E. 
Published: June 2020

The origin of the early proliferating cells of the mammary gland during pregnancy has not been determined. The mammary gland of pregnant rats was studied by light microscopy (Jeffers, 1935). The cytology of the lactating mammary gland and its modes of secretion was studied in mice (Hollmann, 1959), in rats (Bargmann, 1961), and in rabbits (Hollmann, 1966). The present investigation, by electron microscopy, was undertaken to determine the earlier changes in the developing breast during pregnancy, since cellular identification is more easily accomplished by this technique.The mamMary glands of 12 pregnant rats the fifth day following fertilization and every 3 days thereafter until delivery, were studied by electron microscopy. The results show that the myoepithelial cells are the cells responsible for early ductular proliferation. Cytoplasmic processes are seen to project out from these cells into the stromal tissue (Figure 1). Columns of myoepithelial cells may be seen infiltrating the fatty tissue. After this stage the following cellular changes appear: The myoepithelial cells become detached and separated from one another by narrow spaces.
Junction of the Epithelium and Lamina Propria of the Bovine Rumen Mucosa
Authors: Stinson Al W. 
Published: June 2020

The stratified squamous epithelium which lines the ruminal compartment of the bovine stomach performs at least three important functions. (1) The upper keratinized layer forms a protective shield against the rough, fibrous, constantly moving ingesta. (2) It is an organ of absorption since a number of substances are absorbed directly through the epithelium. These include short chain fatty acids, potassium, sodium and chloride ions, water, and many others. (3) The cells of the deeper layers metabolize butyric acid and to a lesser extent propionic and acetic acids which are the fermentation products of rumen digestion. Because of the functional characteristics, this epithelium is important in the digestive process of ruminant species which convert large quantities of rough, fibrous feed into energy.Tissue used in this study was obtained by biopsy through a rumen fistula from clinically healthy, yearling holstein steers. The animals had been fed a typical diet of hay and grain and the ruminal papillae were fully developed. The tissue was immediately immersed in 1% osmium tetroxide buffered to a pH of 7.4 and fixed for 2 hrs. The tissue blocks were embedded in Vestapol-W, sectioned with a Porter-Blum microtome with glass knives and stained with lead hydroxide. The sections were studied with an RCA EMU 3F electron microscope.
Effect of Niacin on Mitochondria of Allium Cepa Root Cells
Authors: Hayat M. Arif 
Published: June 2020

Although it is recognized that niacin (pyridine-3-carboxylic acid), incorporated as the amide in nicotinamide adenine dinucleotide (NAD) or in nicotinamide adenine dinucleotide phosphate (NADP), is a cofactor in hydrogen transfer in numerous enzyme reactions in all organisms studied, virtually no information is available on the effect of this vitamin on a cell at the submicroscopic level. Since mitochondria act as sites for many hydrogen transfer processes, the possible response of mitochondria to niacin treatment is, therefore, of critical interest.Onion bulbs were placed on vials filled with double distilled water in the dark at 25°C. After two days the bulbs and newly developed root system were transferred to vials containing 0.1% niacin. Root tips were collected at ¼, ½, 1, 2, 4, and 8 hr. intervals after treatment. The tissues were fixed in glutaraldehyde-OsO4 as well as in 2% KMnO4 according to standard procedures. In both cases, the tissues were dehydrated in an acetone series and embedded in Reynolds' lead citrate for 3-10 minutes.
Diplotene Achiasmatic Chromosomes Following Normal Synapsis at Pachynema
Authors: Roth Thomas F. , Parchman L. Gerald 
Published: June 2020

Trillium microsporocytes were cultured by normal methods. When strings of meiocytes are explanted from the anther at most stages in meiotic prophase, the chromosomes proceed through an apparently normal prophase. However, if the explantation is carefully chosen at a time just prior to leptonema, prophase is abnormal. In this case, the zygotene and pachytene stages appear similar to control cultures. It is only when the cells reach diplonema that the chromosomes appear to be different.Normally at diplonema the paired homologous bivalent chromosomes of pachynema, separate except where they are held together by one or more chiasmata. In the cells cultured from preleptonema, however, no chiasmata are evident, and where there were formerly a haploid chromosome number of 5 at pachynema, there now are 10 at diplonema through metaphase I (Fig. 1). Although the chromosomes continue to shorten and form a modified metaphase figure, segregation is random. At anaphase I, the chromatids often separate as though it were already anaphase II. Cell plate formation is aberrant in this case, resulting in a highly variable number of chromosomes being segregated into a random number of nuclei, quite unlike the normal tetrad.
Negative Stain Morphology of Herpesvirus-Type Particles Extracted From Tissue Cultures of Human Cells
Authors: Schidlovsky G. 
Published: June 2020

Recent findings of Herpesvirus-type particles in human tissue culture cells originating from “normal” and cancerous individuals have been described. Negative stain studies on the fine structure of these particles (EB-3) indicate that they belong to the herpes group of viruses. However, isolation, immunofluorescence and “coating” tests have ruled out the possibility that this virus is Herpes simplex, Herpes zoster, varicella or cytomegalovirus.It has recently been suggested that members of the papova virus group, although all having the same number of capsomeres, are distinguished from each other by the type of lattice skew present on their capsid. We attempted to detect a similar morphological distinction between the Herpesvirus-type particles and the virus of Herpes simplex. Figure 1 demonstrates the presence of three six-fold capsomeres located along the edge of a triangular face in between two five-fold capsomeres. Since these five capsomeres are located along a straight line the capsid must have a regular icosadeltahedral lattice and must have 162 capsomeres. This makes it identical to the capsid of Herpes simplex virus. We have also repeatedly observed the presence of dark “furrows” on the surface of particles permeated with phosphotungstic acid (PTA) (Fig. 2). Their disposition is compatible only with a regular icosahedral lattice.
Development of St. Louis Encephalitis Virus in the Central Nervous System of the Mouse
Authors: Murphy F. A. , Harrison A. K. , Gary G. W. , Whitfield S. W. 
Published: June 2020

The capacity of St. Louis encephalitis virus to cause destruction of central nervous system tissue is especially well demonstrated in experimental infection of the mouse. Inoculation of the virus intracerebrally rather than peripherally broadens the usual focal distribution of brain lesions; and when neonatal rather than older animals are inoculated intracerebrally, the infection is characterized by a widespread destructive process.In the present investigation, St. Louis encephalitis virus isolated by the Arbovirus Unit, NCDC, from brain tissue from a fatal human case in Dallas, Texas during an encephalitis epidemic in 1966 was used. A standard laboratory strain of the virus was also studied. Two-day-old Swiss mice were inoculated intracerebrally with approximately 103 LD50 of virus, and brain tissue was harvested from moribund animals 4 days later. Tissue was fixed in glutaraldehyde, post-fixed in OsO4, dehydrated in an ethanol series and embedded in an Araldite-Epon mixture. Sections were stained with lead citrate or uranyl acetate.
The Use of the “Microdiluter” and “Ionized” Carbon Films for Negative Staining
Authors: Stephens R. , Schidlovsky G. , Kuzmic S. 
Published: June 2020

When comparing the virus concentration of various samples by negative staining it is necessary to be able to deliver consistently equal but small volumes of virus suspension and phosphotungstic acid solution (PTA). These two components have to be thoroughly mixed prior to deposition on a grid coated with a hydrophilic film.We have found that the “microdiluter” is a convenient and economical tool for consistent dispensing of known and small equal volumes of virus suspension (0.025 or 0.05 ml). We are quantitating mouse leukemia and herpes-type virus particles suspended in 0.05 M Na Citrate. The metallic tool works by capillary action and must be pre-wetted with buffer and blotted prior to pick-up of the virus suspension for reproducible results. PTA is delivered with a pipette dropper calibrated to dispense 0.025 or 0.05 ml per drop.
Use of Uranium-Labeled Antibodies for Electron Microscopic Localization of Various Antigens in Mammalian Cells
Authors: Petrali J. P. , Donati E. J. , Sternberger L. A. 
Published: June 2020

Specific contrast is conferred to subcellular antigen by applying purified antibodies, exhaustively labeled with uranium under immunospecific protection, to ultrathin sections. Use of Seligman’s principle of bridging osmium to metal via thiocarbohydrazide (TCH) intensifies specific contrast. Ultrathin sections of osmium-fixed materials were stained on the grid by application of 1) thiosemicarbazide (TSC), 2) unlabeled specific antiserum, 3) uranium-labeled anti-antibody and 4) TCH followed by reosmication. Antigens to be localized consisted of vaccinia antigen in infected HeLa cells, lysozyme in monocytes of patients with monocytic or monomyelocytic leukemia, and fibrinogen in the platelets of these leukemic patients. Control sections were stained with non-specific antiserum (E. coli).In the vaccinia-HeLa system, antigen was localized from 1 to 3 hours following infection, and was confined to degrading virus, the inner walls of numerous organelles, and other structures in cytoplasmic foci. Surrounding architecture and cellular mitochondria were unstained. 8 to 14 hours after infection, antigen was localized on the outer walls of the viral progeny, on cytoplasmic membranes, and free in the cytoplasm. Staining of endoplasmic reticulum was intense and focal early, and weak and diffuse late in infection.