bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on tubular myelin figures of lining layer of lung alveoli
Authors: Groniowski Janusz , Walski MichaŁ 
Published: June 2020

Extracellular alveolar lining layer of mammalian lungs is rich in phospholipids associated or bound to proteins and carbohydrates. There are implications that all the molecular components aggregate in an obligatory sequence and that protein has an organizing role. In electron microscopy alveolar lining layer is composed of a surface film and a liquid subphase. The latter is marked with tubular myelin figures /TMF/. In this report some attempts to characterize more precisely the TMF are presented.Prefixation of tissue samples in osmium or glutaraldehyde vapor was followed by fixation in diluted Kamovsky′ s fixative. The TMF is composed of lamellae showing the unit membrane structure. On cross section the TMF reveal a square lattice pattern. The centre of each square contains fragments of a somewhat circular profile /Fig. 1/, suggesting also their linear continuity along the axis of each tubule. The tridimensional reconstruction reveals that the fragments may belong to a randomly coiled formation located in the centre of tubule.
Plasmalemma localisation of inorganic phosphate in B cells pancreas
Authors: Wooding F. B. P. , Pedley K. , Freinkel N. , Dawson R. M. C. 
Published: June 2020

Freinkel et al (1974) demonstrated that isolated perifused rat pancreatic islets reproduceably release up to 50% of their total inorganic phosphate when the concentration of glucose in the perifusion medium is raised.Using a slight modification of the Libanati and Tandler (1969) method for localising inorganic phosphate by fixation-precipitation with glutaraldehyde-lead acetate we can demonstrate there is a significant deposition of lead phosphate (identified by energy dispersive electron microscope microanalysis) at or on the plasmalemma of the B cell of the islets (Fig 1, 3). Islets after incubation in high glucose show very little precipitate at this or any other site (Fig 2). At higher magnification the precipitate seems to be intracellular (Fig 4) but since any use of osmium or uranyl acetate to increase membrane contrast removes the precipitate of lead phosphate it has not been possible to verify this as yet.
Electron microscope study of the microgranules in human vaginal epithelium
Authors: Campos A. , Vilches J. , Gomez J. 
Published: June 2020

Microgranules have been described with different names in keratinized and in nonkeratinized epithelium. In keratinized epithelium it seems clear that the microgranules are lamellated bodies bounded by a membrane which empty their contents into the intercellular space. Their existence in nonkeratinized epithelium is more debatable. Until now the so-called microgranules have been described in nonkeratinized bucal, lingual and cervical epithelium. In the present work we describe the morphology and nature of such structures in human vaginal epithelium.Biopsies from the midlevel of the vaginal mucosa were taken from voluntary fertile women. The specimens were divided into three groups with four vaginal specimens. The first group was obtained in the folicular phase; those of the second in the postovulatory phase and, finally, the last group corresponded to the secretory phase.
Dense core tubuli—a new structural element of the spermatophores of pogonophora
Authors: Flügel H. 
Published: June 2020

Pogonophora are tube-dwelling marine invertebrates without a digestive tract. They feed entirely on dissolved organic matter which occurs in traces in the sea water. Their phylogenetic position is still controversial. In spite of numerous anatomical investigations using the light microscope our knowledge of their reproduction is still limited (Ivanov, 1963; Webb, 1963a, b; Southward, 1975). It is well established that the sexes are separate. The sperm is discharged in the form of elongated spermatophores and the eggs are fertilized in the forepart of the tube, at least in the families Siboglinidae and Oligobrachiidae.But the mechanism of fertilization has not yet been observed. Electron microscopic investigations of the spermatophores may help to elucidate the biology of reproduction. Investigations on the spermiogenesis and the spermatophores of Siboglinum ekmani were carried out recently (Franzén, 1 973; Flügel, 1977).
Ultrastructural study of the adrenocortical homologue in freshwater and seawater adapted eels
Authors: Kumar Bhattacharyya Tapan , Gordon Butler David 
Published: June 2020

The teleost fishes have been extensively utilized to explore the biochemical nature of adrenocortical steroids, pathways of steroidogenesis and the metabolic role of adrenocortical steroids. The adrenocortical homologue (AH) has been localized in more than two hundred species of teleosts, although the fine structure of teleost AH has been studied only in the goldfish. It seemed to be of interest to investigate the normal fine structure of this endocrine organ in another zoologically important teleost species, the north American eel (Anguilla rostrata) as a baseline for experimental studies. This animal being a euryhaline species, the AH ultrastructure of animals exposed to artificial seawater for a long period (1 1/2 years) was also examined.Mature female silver eels held in freshwater(FW) and seawater(SW) aquaria were anesthetized and perfused with glutaraldehyde in phosphate buffer or formaldehyde-glutaraldehyde in cacodylate buffer, and glutaraldehyde containing 0. 2% digitonin for demonstration of cholesterol.
A study of synaptic morphology in the trigeminal motor nucleus utilizing the HRP method
Authors: Konishi A. , Mizuno N. , Nomura S. , Itoh K. , Nakamura Y. 
Published: June 2020

The synaptic organization of the motor nucleus of the trigeminal nerve in the cat was examined electron microscopically after labelling the motoneurons or the axon terminals on the motoneurons by retrograde or anterograde axonal transport of horseradish peroxidase (HRP).The experiments were carried out on young adult cats (1. 5 to 3. 0 kg) anesthetized with intraperitoneal Nembutal (35 mg/kg). For labelling the motoneurons, 2% solution of HRP (Toyobo Grade-I-C, RZ: 3. 4) dissolved in sterile 0. 9% saline was injected within the muscle belly of the temporal, masseter or anterior digastric muscle with a fine caliber intradermic needle attached to a syringe. For labelling axon terminals of the commissural fibers arising contralaterally from the commissural interneurons around the trigeminal motor nucleus, a single injection of 0. 05 μ l of 50% HRP dissolved in 2% dimethylsulfoxide or in sterile 0. 9% saline was performed stereotaxically within the trigeminal motor nucleus and its adjacent regions.
Characterization of the synaptic membranes in the central nervous system through electron microscopic immunocytochemistry of the botulinum toxin
Authors: Toxin Botulinum , Iiirokawa Nobutaka , Kitamura Masaru 
Published: June 2020

Synapses are established between neurites of nerve cells and target cells (e. g. neurons, muscles, sensory cells). Synaptic membranes differentiate to show two main characteristics: one is for release of neurotransmitters and the other is for recognition of its partner during development. Many investigations have been undertaken to visualize the characteristics of the synaptic membranes by lectins, PTA staining and freeze fracture technique. The precise substantial nature of the synaptic membranes, however, has little been known till now. In the present study we intend to characterize synaptic membranes through electron microscopic immunocytochemistry of the botulinum toxin. The binding site of this neurotoxin is supposed to be specific gangliosides and it is well known that the toxin blocks the transmitter release at the neuromuscular junction and gangliosides may contribute much in neuronal recognition.The botulinum toxin type A cristalline toxin was supplied by Dr. E. J. Schantz(Wiseonsin Univ. ).
Rod and cone-type photoreceptors in the post-equatorial region of the albino rat retina: a morphometric analysis of their incidence and fine structure
Authors: Jonson K. M. , Champion R. A. , Shorey C. D. , Beaumont P. E. 
Published: June 2020

The existence of cones in the rat retina is controversial. Although the rat has been thought to possess an exclusive rod retina (Lashley, 1932; Detwiler, 1943), Walls (1934) reported the existence of “typical cones” essentially similar to those of the primate. More recent light and electron microscope studies have also reported on the presence of cones in the rat retina (Leure-duPree, 1974; LaVail, 1976). A quantitative analysis of their incidence and fine structure has not previously been reported.The results of the present investigation demonstrate that although the rat photoreceptor layer is rod-dominant, approximately 17% of its cells would, on morphological grounds, qualify as “cone-type” receptors. These, however, are not typical cones, as their inner and outer segments do not show the characteristic conical taper and appear morphologically similar to the slender cylindrical-shaped rod inner and outer segment. Apart from this, the rat cone-type receptor cell does resemble the cone typically observed in other species.
Cell differentiation in the olfactory pit of the chick embryo
Authors: Kasuga S. , Okano M. , Sugawa Y. 
Published: June 2020

It is well known that the development of the olfactory organ derives from the epithelium lining the surface of the olfactory pit which developed from the ectodermal olfactory placode. The development of the olfactory epithelium has been explored in the chick embryo(Robecchi; 1972, Breipohl and Fernandez;1977) and the mouse embryo(Cuschieri and Bannister;1975, Graziadei and Okano;1978) to a certain extent.In order to investigate the cellular differentiation of chemoreceptor cells in the olfactory organ proimordium, the olfactory placode of the chick embryo(50-53 incubation hours, Hamburger and Hamilton, 1951) and the olfactory pit of the chick embryo(52-69 incubation hours, HH) are utilized in this study with the aid of a scanning and a transmission electron microscope.Olfactory placode; the placode is recognized on the antero-lateral aspect of the head of the chick embryo(50-53 incubation hours, HH), and distingwished from the general surrounding ectoderm as a circular territory of 140 μm in diameter, and the cellular arrangement at the placode surface observed by a scanning electron microscope is characteristic and recognized as a rosette consisted from several oval swollen cellular endings (olfactory. vesicles) which have a single cilium and few microvilli, and the other intercalated cellular elements(supporting cells) (Fig. 1).
Calcium localization in fast frog muscle fibers at rest and during potassium contracture
Authors: Samosudova N.V. , Ludkovskaya R.G. 
Published: June 2020

There is abundant data in the muscle literature referring to Ca as the activator of the contractile system. The intracellular calcium localization in the fast frog muscle fibers at rest and during K-contrac-ture was studied by electron microscopy combined with pyroantimonate- osmium technique. It appears that the increased Ca-concentration in the myofibrillar space has to be maintained for the development of the prolonged contraction. The fast fibers are not capable of maintaining the prolonged contraction in solution with a high K-concentration. however the prolonged potassium contracture of fast fibers was obtained in response to the action of the KSCN-solution (20 mM). Anion SCN¯ inhibits Ca - uptake by sarcoplasmic reticulum and thus slows down the relaxation.In the present study we have given the main attention to localization of myofibrillar calcium.Three Ca-accumulating lines, corresponding to the N-lines, were observed in the I band of stretched fibers (the sarcomere length 3.2 μm) at a distance of N1 - 0.44, N2 - 0.55, N3 - 0.67μ from the Z line (fig. 1).
X-ray microanalytical and enzyme-cytochemical study on vesical malacoplakia
Authors: Hokano Masami , Oh-I Tsunao , Narita Yoshie , Sassa Hiroshi , Saburo Suzuki  
Published: June 2020

Malacoplakia is a kind of granulomatous inflammation and characterized by the presence of calcium-stain positive granules (Michaelis-Gutmann bodies, hereinafter abbreviated as M-G bodies ) in the macrophages.In this report we want to say about the following articles:the ultrastruc tural findings in four cases of vesical malacoplakia;the ultrastructural morphogenesis of the M-G bodies;X-ray microanalytical studies which examine the change of the chemical component of M-G bodies, according to their developing stages; andacid phosphatase activity of lysosome within the malacoplakic macrophages.Biopsy materials taken from four cases with vesical malacoplakia were divided into 2 parts; one for a light microscopy and the other for an electron microscopy. The specimen for an electron microscopy was fixed in glutaraldehyde and osmium tetroxide, dehydrated in ethanol and then embedded in Epon 812. Ultrathin sections were doublestained with lead citrate and uranyl acetate and then subjected to routin TEM observation. For X-ray microanalysis was mounted an energy dispersive X-ray microanalyzer on a JEM-100 C type electron microscope. Ultrathin sections for microanalysis were cut 100-200nm thich and not stained.
New aspects of articular cartilage transplantation with TEM and SEM
Authors: Hesse W. , Hesse I. 
Published: June 2020

Much experimental work has been done in the field of transplantation of articular cartilage. The data are very conflicting. As these investigations were usually performed with routine histological techniques, the ultrastructure and functions of the chondrocytes of the grafts were not examined. Likewise the morphology of the surface, which is the important factor in the function of the joint, was not studied in previous experiments. The purpose of this presentation is to describe the ultrastructure of osteo-chondral grafts to obtain new evidence on the healing process of cartilage transplants.In our experiment osteo-chondral grafts were implanted in 150 animals. The animals were divided into four groups: 1) 30 sheep with fresh homologous grafts, 2) 15 sheep with autologous grafts. 3) 20 rabbits with stored homologous grafts, 4) 35 rabbits with autologous grafts. The grafts consisting of the articular cartilage and a narrow margin of cancellous bone measured 3. 5 mm in thickness.
Compositional imaging in the Electron Microscope
Authors: Lyman C. E. 
Published: June 2020

Imaging of elemental distributions on a fine scale is one of the triumphs of electron microscopy. Compositional imaging frees the operator from the necessity of making decisions about which features contain the elements of interest. Elements in unexpected locations, or in unexpected association with other elements, may be found easily without operator bias as to where to locate the electron probe for compositional data collection. This technique may be applied to bulk or thin specimens using a variety of composition-sensitive signals as shown in Figure 1.Cosslett and Duncumb obtained the first such compositional image in an electron microprobe modified to scan the electron beam and collect a characteristic x-ray signal as a function of beam position. Early images of this type were called x-ray “dot maps” and provided a qualitative indication of the location of elements on a flat polished bulk specimen to a spatial resolution of about 1 μm.
Scleroderma crest autoantibodies as fluorescent and Immuno-Electron Microscopic probes: Keys to a chromosomal black box
Authors: Brinkley B. R. , Zinkowski R. P. 
Published: June 2020

The mammalian kinetochore is a highly differentiated structure found at the centromere (primary constriction) of chromosomes that serves as an attachment site for spindle microtubules. Ultrastructurally, the kinetochore typically appears as a tri-layered plate or disc situated at the sides of the centromere (Fig.1). Recent evidence demonstrates that kinetochores have the ability to capture and stabilize microtubules that grow from the spindle poles. Moreover, the motor(s) for chromosome movement appear to be located in or near the kinetochore which actively participates in the generation of forces necessary for chromosome movement in mitosis and meiosis. To understand how the precise ballet-like movements of chromosomes on the mitotic spindle occur, attention has focused on the “black box” of the chromosome; the centromere-kinetochore complex.The fortuitous discovery that serum from individuals with the CREST variant of scleroderma contain autoantibodies that bind to components of the centromere-kinetochore complex has led to major advancements in the understanding of this chromosomal black box. Indirect immunofluorescence has demonstrated the presence of paired fluorescent structures (Fig.2) at the centromeres of both mammalian and plant chromosomes.
Autoantibodies as probes for the molecular architecture of the nucleus
Authors: Spector David L. , Lark Gayle , Sovak Mika , Huang Sui 
Published: June 2020

Autoantibodies to a variety of nuclear components including DNA, histones, DNA polymerases, DNA topoisomerases, lamins, coiled bodies, RNA polymerase I, and several classes of ribonucleoproteins have been identified in the sera of individuals with autoimmune disorders. We have taken advantage of autoantibodies to several major classes (U1, U2, U4/U6, U5) of small nuclear ribonucleoprotein particles (snRNPs) which play a crucial role in the processing of pre-mRNA molecules. We have used these antibodies to evaluate the organization of factors which participate in pre-mRNA splicing in the mammalian cell nucleus.We have previously shown snRNPs to be localized to discrete immunostained regions, “speckles”, which form a latticework within the interphase nuclei of several mammalian cell types. Since RNA polymerase II, which is involved in the synthesis of pre-mRNA, is highly sensitive to a-amanitin we were interested in the effect of an inhibition of pre-mRNA synthesis on the snRNP distribution pattern. Cells incubated in drug for 5 hours (Fig. 1d) showed no detectable effect on the organization of snRNPs nor any effect on the level of transcription.
Three-dimensional light microscopy for the analysis of chromosome organization in Drosophila embryo
Authors: Hiraoka Yasushi , Dernburg Abby F. , Parmelee Susan J. , Rykowski Mary C. , Agard David A. , Sedat John W. 
Published: June 2020

We are interested in the three-dimensional physical relationships among chromosomes in mitotically active nuclei. Using high-resolution, three-dimensional optical sectioning microscopy incorporating a charge-coupled device (CCD), we have analyzed the spatial arrangements of chromosomes in nuclei from Drosophila melanogaster embryos. During early stages of nuclear division, these embryos exist as syncytial blastoderms, with up to 5000 nuclei forming a single layer near the embryo's surface and dividing essentially synchronously. This greatly facilitates the analysis of chromosome organization because of the simple monolayer arrangement of nuclear structures at defined mitotic stages.From prophase to anaphase, three-dimensional paths of condensed chromosomes stained with a DNA-specific fluorescent dye can be traced using an interactive computer program. We have used this method to ask the specific biological question of whether pairs of homologous chromosomes have a consistent, ordered arrangement in diploid nuclei. Our results have shown that homologous chromosomes are not associated with each other from prophase to anaphase in syncytial blastoderm stage embryos.
A plunge-freezing method for imaging mammalian tissue culture cells
Authors: O'Toole E.T. , McIntosh J.R. 
Published: June 2020

Ultrarapid freezing of tissue culture cells followed by freeze substitution has been used a method for the optimum fixation of cytoskeletal components that are often sensitive to routine chemical fixation. This is due to the fact that freezing methods such as plunge freezing, result in the almost instantaneous fixation of all cellular components without alteration of the cell's morphology. In addition, we have found that the plunge freezing method is useful for obtaining thin frozen cells for direct cryoimaging. Here we describe how the plunge freezing method can be applied both for freeze substitution analysis and for direct cryoimaging of frozen tissue culture cells.PTK, cells were grown to confluence on formvar coated, carbon stabilized gold grids. Prior to freezing, the grids were blotted in a 37°C, high humidity chamber so that a minimum of culture medium remained on the grid. This blotting step was critical to obtain a sample thin enough for optimum cryopreservation and subsequent cryoimaging.
Ultrastructural observations of human monocytes infected with HIV-1
Authors: Koehler James K. , Reed Steven G. , Silva Joao S. 
Published: June 2020

As part of a larger study involving the co-infection of human monocyte cultures with HIV and protozoan parasites, electron microscopic observations were made on the course of HIV replication and infection in these cells. Although several ultrastructural studies of the cytopathology associated with HIV infection have appeared, few studies have shown the details of virus production in “normal,” human monocytes/macrophages, one of the natural targets of the virus, and suspected of being a locus of quiescent virus during its long latent period. In this report, we detail some of the interactions of developing virons with the membranes and organelles of the monocyte host.Peripheral blood monocytes were prepared from buffy coats (Portland Red Cross) by Percoll gradient centrifugation, followed by adherence to cover slips. 90-95% pure monocytes were cultured in RPMI with 5% non-activated human AB serum for four days and infected with 100 TCID50/ml of HIV-1 for four hours, washed and incubated in fresh medium for 14 days.
Correlative light microscopy, electron microscopy, and cytochemistry of cytoskeletal structures in motile fibroblasts
Authors: Heath Julian P. , Turner Donna , Holifield Bruce F. 
Published: June 2020

Contrast-enhanced video differential interference contrast microscopy (VDICM) is revealing new details about the dynamics of F-actin assemblies in motile cells. We are using correlative single cell light and electron microscopy and immunocytochemistry to understand the dynamic interactions of the actin cytoskeleton in lamellipodia and the leading lamella.Fibroblasts were cultured on carbon-coated glass #1 coverslips and examined on a Zeiss Axiophot. Cells were perfused with 1% glutaraldehyde (GA) in PIPES buffer and fixed for 15 min., quenched with 1 mg/ml borohydride/PBS and extracted with 0.1% Triton X-100 in PBS for 1 min. Cell postions were marked with a diamond objective, and the cells were incubated for 30 min. with 0.6 uM rhodamine-conjugated phalloidin to stain for F-actin. Light and fluorescence micrographs were taken on fine-grained film. After photography, cells were further fixed in 2.5% GA, postfixed in 1% osmium, dehydrated in ethanol and embedded in Spurrs resin. The glass was removed by scoring with a diamond pencil followed by immersion in liquid N2. Cells were relocated in the blocks by phase-contrast microscopy. Thin (80 nm) sections were examined in Philips EM 410 at 60 kV on a dicentric goniometric stage.