Search results for "Histology"
showing 10 items of 985 documents
Direct interpretation of near-field optical images.
2001
The interpretation of the detection process in near-field optical microscopy is reviewed on the basis of a discussion about the possibility of establishing direct comparisons between experimental images and the solutions of Maxwell equations or the electromagnetic local density of states. On the basis of simple physical arguments, it is expected that the solutions of Maxwell equations should agree with images obtained by collecting mode near-field microscopes, while the electromagnetic local density of states should be considered to provide a practical interpretation of illumination mode near-field microscopes. We review collecting mode near-field microscope images where the conditions to o…
Peculiarities of imaging one- and two-dimensional structures using an electron microscope in the mirror operation mode.
2001
Measurements performed in an electron microscope with the mirror operation mode are most sensitive to local electric fields and geometrical roughness of any kind of the object being studied. The object with a geometrical relief is equivalent to a smooth surface with an effective distribution of microfields. Electrons forming the image interact with the local microfields for an extended time: during approach to the object, deceleration and acceleration away from the object. As a result, the electron trajectories can be strongly distorted, and the contrast changes essentially, leading to image deformation of details of the object under investigation and to lowering of the resolution. These ef…
The Innervation of Taste Buds in the Soft Palate of the Rat as Revealed by Methylene Blue Staining.
1996
Light microscopic data on the innervation of taste buds in the soft palate of the rat obtained by methylene blue (MB) supravital staining are presented here for the first time. The taste pore including subpopulations of taste bud cells and nerve fibers were stained. Intragemmal nerve fibers were detected ascending up to the taste pore; this suggests the possibility of additional paracellular pathways in taste transduction directly via nerve fibers. Moreover, relatively large bulbous or laminar enlargements of the intragemmal nerve fibers were found. The branches of these nerve fibers, showing minute spiny protuberances, appeared to anastomose. Some perigemmal nerve fibers were also seen in …
Quasi-spherical focal spot in two-photon scanning microscopy by three-ring apodization
2005
International audience; We present a beam-shaping technique for two-photon excitation (TPE) fluorescence microscopy. We show that by inserting a properly designed three-ring pupil filter in the illumination beam of the microscope, the effective optical sectioning capacity of such a system improves so that the point spread function gets a quasi-spherical shape. Such an improvement, which allows the acquisition of 3D images with isotropic quality, is obtained at the expense of only a small increase of the overall energy in the axial sidelobes. The performance of this technique is illustrated with a scanning TPE microscopy experiment in which the image of small beads is obtained. We demonstrat…
Synapses between NG2 glia and neurons
2011
NG2-expressing glia are precursors to oligodendrocytes and subpopulations of astrocytes. They are unique among glial cells in that they enter into synaptic specialisations with neurons throughout all areas of grey and white matter and at all ages. To date, the NG2 cells appear to represent a postsynaptic compartment, and synapses are formed with axons. With differentiation to oligodendrocytes, NG2 is downregulated and myelin antigens upregulated: this coincides with a loss of the synaptic contacts between neurons and NG2 glial cells. The functional roles of this glial–neuron synapse in regulation of differentiation into myelinating oligodendrocytes or additionally responding to and modulati…
Differentiation-associated apoptosis of neural stem cells is effected by Bcl-2 overexpression: impact on cell lineage determination
2001
Apoptosis is an integral part of neural development. To elucidate the importance of programmed cell death on cell lineage determination we utilized murine PCC7-Mzl cells, a model system for neural differentiation. Treatment of pluripotent PCC7-Mzl stem cells with 0.1 microM all-trans retinoic acid (RA) causes a cease of proliferation and an initiation of differentiation into neurons, glial cells and fibroblasts. Simultaneously, a fraction of the cell culture (ca. 25%) dies within 24 h by apoptosis. We transfected PCC7-Mzl cells with the human bcl-2 cDNA and generated PCC7-Mz-Bcl-2 cell lines expressing two- to tenfold higher levels of Bcl-2 than parental cells. Overexpression of Bcl-2 resul…
Characterization of cells with different mitochondrial membrane potential during apoptosis.
2005
Background Until now, the simultaneous analysis of several parameters during apoptosis, including DNA content and mitochondrial membrane potential (ΔΨ), has not been possible because of the spectral characteristics of the commonly used dyes. Using polychromatic flow cytometry based upon multiple laser and UV lamp excitation, we have characterized cells with different ΔΨ during apoptosis. Methods U937 cells were treated with the flavonoid quercetin (Qu) and stained with JC-1 to detect ΔΨ, propidium iodide (PI) for cell viability, Hoechst 33342 for DNA content, Annexin V conjugated with Alexa Fluor-647 for detection of phosphatidilserine (PS) exposure, marker of early apoptosis, or Mitotracke…
Biological properties of extracellular vesicles and their physiological functions
2015
The authors wish to thank Dr R Simpson and Dr D Taylor for critical reading of the manuscript and acknowledge the Horizon 2020 European Cooperation in Science and Technology programme and its support of our European Network on Microvesicles and Exosomes in Health & Disease (ME-HaD; BM1202 www.cost.eu/COST_Actions/bmbs/Actions/BM1202). In the past decade, extracellular vesicles (EVs) have been recognized as potent vehicles of intercellular communication, both in prokaryotes and eukaryotes. This is due to their capacity to transfer proteins, lipids and nucleic acids, thereby influencing various physiological and pathological functions of both recipient and parent cells. While intensive invest…
�ber das Zwischenhirn-Hypophysensystem vonProtopterus annectens
1957
1. Das neurosekretorische Zwischenhirn-Hypophysensystem vonProtopterus annectens zeigt in bezug auf Ausdehnung und Anordnung seiner Anteile sehr starke Ahnlichkeit mit dem der anuren Amphibien. 2. Der Nucleus praeopticus liegt zu beiden Seiten des 3. Ventrikels. Er erstreckt sich dorsal bis unter das Ependym und ventral bis zum Chiasma opticum. Seine Ganglienzellen sind gros mit rundem glattrandigem Kern. Sie enthalten wenig peripher gelegene Kugeln und Granula von Neurosekret, das offenbar auf Kosten der Nissl-Substanz gebildet wird. 3. Der Tractus praeoptico-hypophyseus beginnt wie bei den Anuren mit 2 Teilen, einem rostro-ventral im Bogen verlaufenden und einem direkt schrag von dorsal n…
�ber den Feinbau der Paraphyse vonProtopterus annectens
1957
1. Die Paraphyse vonProtopterus annectens ist eine Aussackung des hautigen Zwischenhirndaches, in die hinein sich der 3. Ventrikel fortsetzt. 2. Ihre Wandung besteht aus einem einschichtigen Epithel, das besonders im medialen und rostralen Bereich des Organs stark gefaltet ist. Die Falten engen das Ventrikellumen ein. An der Basis des Epithels liegen Kapillaren. 3. Die kubischen Epithelzellen tragen an ihrer Oberflache einen Burstensaum. Sie enthalten Vakuolen und stark farbbare Tropfen; an der freien Zelloberflache liegen abgeschnurte Ballen von Sekret. Diese Erscheinungen werden als Zeichen fur eine lebhafte sekretorische Tatigkeit des Paraphysenepithels angesehen. 4. Zwischen dem Paraphy…