scholarly journals ELECTRON MICROSCOPE AND EXPERIMENTAL INVESTIGATIONS OF THE NEUROFILAMENTOUS NETWORK IN DEITERS' NEURONS

1974 ◽  
Vol 61 (3) ◽  
pp. 701-722 ◽  
Author(s):  
J. Metuzals ◽  
W. E. Mushynski
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Interference Microscopy ◽  
Experimental Investigations ◽  
Rabbit Brain ◽  
Nuclear Pores ◽  
Isolated Cells ◽  
Thin Sections ◽  
Space Network ◽  
Neurofilamentous Network

The assembly of filamentous elements and their relations to the plasma membrane and to the nuclear pores have been studied in Deiters' neurons of rabbit brain. Electron microscopy of thin sections and of ectoplasm spread preparations have been integrated with physicochemical experiments and differential interference microscopy of freshly isolated cells. A neurofilamentous network extends as a continuous, three-dimensional, semilattice structure throughout the ectoplasm, the "plasma roads," and the perinuclear zone of the perikaryon. This space network consists of ∼90-Å wide neurofilaments arranged in fascicles which are interconnected by an exchange of neurofilaments. The neurofilaments consist of intercoiled ∼20-Å wide unit-filaments and are associated through cross-associating filaments with other neurofilaments of the fascicle and with microfilaments. The ∼20–50-Å wide microfilaments display intimate associations with the plasma membrane and with the nuclear pores. Electron microscopy of thin sections from glycerinated and heavy meromyosin-treated Deiters' neurons shows that actin-like filaments are present in the pre- and postsynaptic regions of synapses terminating on these neurons. It is proposed that the neurofilamentous space network serves a transducing function by linking plasma membrane activities with the genetic machinery of the neuron.

scholarly journals Initial events during phagocytosis by macrophages viewed from outside and inside the cell: membrane-particle interactions and clathrin.

1982 ◽  
Vol 94 (3) ◽  
pp. 613-623 ◽  
Author(s):  
J Aggeler ◽  
Z Werb
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Plasma Membranes ◽  
Cell Attachment ◽  
High Resolution Electron Microscopy ◽  
Peritoneal Macrophages ◽  
Coated Pits ◽  
Thin Sections ◽  
Particle Uptake ◽  
Freeze Dried

The initial events during phagocytosis of latex beads by mouse peritoneal macrophages were visualized by high-resolution electron microscopy of platinum replicas of freeze-dried cells and by conventional thin-section electron microscopy of macrophages postfixed with 1% tannic acid. On the external surface of phagocytosing macrophages, all stages of particle uptake were seen, from early attachment to complete engulfment. Wherever the plasma membrane approached the bead surface, there was a 20-nm-wide gap bridged by narrow strands of material 12.4 nm in diameter. These strands were also seen in thin sections and in replicas of critical-point-dried and freeze-fractured macrophages. When cells were broken open and the plasma membrane was viewed from the inside, many nascent phagosomes had relatively smooth cytoplasmic surfaces with few associated cytoskeletal filaments. However, up to one-half of the phagosomes that were still close to the cell surface after a short phagocytic pulse (2-5 min) had large flat or spherical areas of clathrin basketwork on their membranes, and both smooth and clathrin-coated vesicles were seen fusing with or budding off from them. Clathrin-coated pits and vesicles were also abundant elsewhere on the plasma membranes of phagocytosing and control macrophages, but large flat clathrin patches similar to those on nascent phagosomes were observed only on the attached basal plasma membrane surfaces. These resulted suggest that phagocytosis shares features not only with cell attachment and spreading but also with receptor-mediated pinocytosis.

The fine structure of Sphaerotilus nutans

1973 ◽  
Vol 19 (3) ◽  
pp. 309-313 ◽  
Author(s):  
Judith F. M. Hoeniger ◽  
H.-D. Tauschel ◽  
J. L. Stokes
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Lateral Position ◽  
Thin Sections ◽  
Liquid Cultures ◽  
Sphaerotilus Natans ◽  
Stationary Liquid ◽  
Basal Disk ◽  
Polar Organelle

Sphaerotilus natans developed sheathed filaments in stationary liquid cultures and motile swarm cells in shaken ones. Electron microscopy of negatively stained preparations and thin sections showed that the sheath consists of fibrils. When the filaments were grown in broth with glucose added, the sheath was much thicker and the cells were packed with granules of poly-β-hydroxybutyrate.Swarm cells possess a subpolar tuft of 10 to 30 flagella and a polar organelle which is usually inserted in a lateral position and believed to be ribbon-shaped. The polar organelle consists of an inner layer joined by spokes to an accentuated plasma membrane. The flagellar hook terminates in a basal disk, consisting of two rings, which is connected by a central rod to a second basal disk.

scholarly journals The Rab11 Pathway Is Required for Influenza A Virus Budding and Filament Formation

2010 ◽  
Vol 84 (12) ◽  
pp. 5848-5859 ◽  
Author(s):  
Emily A. Bruce ◽  
Paul Digard ◽  
Amanda D. Stuart
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Influenza A Virus ◽  
Membrane Trafficking ◽  
Influenza A ◽  
Spherical Particles ◽  
Actin Dynamics ◽  
Apical Plasma Membrane ◽  
Thin Sections ◽  
Virus Particles

ABSTRACT Influenza A virus buds through the apical plasma membrane, forming enveloped virus particles that can take the shape of pleomorphic spheres or vastly elongated filaments. For either type of virion, the factors responsible for separation of viral and cell membranes are not known. We find that cellular Rab11 (a small GTP-binding protein involved in endocytic recycling) and Rab11-family interacting protein 3 ([FIP3] which plays a role in membrane trafficking and regulation of actin dynamics) are both required to support the formation of filamentous virions, while Rab11 is additionally involved in the final budding step of spherical particles. Cells transfected with Rab11 GTP-cycling mutants or depleted of Rab11 or FIP3 content by small interfering RNA treatment lost the ability to form virus filaments. Depletion of Rab11 resulted in up to a 100-fold decrease in titer of spherical virus released from cells. Scanning electron microscopy of Rab11-depleted cells showed high densities of virus particles apparently stalled in the process of budding. Transmission electron microscopy of thin sections confirmed that Rab11 depletion resulted in significant numbers of abnormally formed virus particles that had failed to pinch off from the plasma membrane. Based on these findings, we see a clear role for a Rab11-mediated pathway in influenza virus morphogenesis and budding.

scholarly journals MEASUREMENT OF THICKNESS WITHIN SECTIONS BY QUANTITATIVE ELECTRON MICROSCOPY

1969 ◽  
Vol 40 (3) ◽  
pp. 768-772 ◽  
Author(s):  
Lloyd Silverman ◽  
Berit Schreiner ◽  
David Glick
Keyword(s):  
Electron Microscopy ◽  
Phosphotungstic Acid ◽  
Exchange Resin ◽  
Interference Microscopy ◽  
Quantitative Electron Microscopy ◽  
Thin Sections ◽  
Calculated Mass ◽  
Thickness Standard ◽  
Embedding Medium ◽  
Measurement Of Thickness

To apply the method of quantitative electron microscopy to the measurement of mass in thin sections, the thickness of the section at or very near the structure to be studied must be known. Dowex anion exchange resin AG 1 x 2, stained with phosphotungstic acid (PTA) at pH 6.4, was used as a thickness standard which could be embedded and sectioned. The sectioned PTA-Dowex appeared uniformly stained and exhibited suitable electron opacity. The stoichiometry of the reaction between PTA and the Dowex resin was measured by three independent methods based on gravimetric, colorimetric, and nitrogen determinations whose results showed close agreement. From the PTA uptake, the density of the stained spheres was calculated. Mass of a defined area of PTA-Dowex was measured by quantitative electron microscopy, and from this mass and density, the volume and then the thickness were calculated. The values for thickness were compared to those obtained by interference microscopy on the embedding medium alone in the same sections.

Ultrastructural aspects of coated vesicles in tobacco protoplasts

1981 ◽  
Vol 59 (7) ◽  
pp. 1307-1313 ◽  
Author(s):  
P. van der Valk ◽  
L. C. Fowke
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Plasma Membrane ◽  
Coated Vesicles ◽  
Thin Sections ◽  
Tobacco Protoplasts ◽  
Vesicle Membranes ◽  
Transmission Electron ◽  
Large Numbers ◽  
Inner Surface

The ultrastructure and distribution of coated vesicles in isolated tobacco protoplasts were investigated using transmission electron microscopy of thin sections of whole protoplasts and stained plasma membrane preparations obtained by osmotic bursting of protoplasts attached to coated microscope grids. Large numbers of coated vesicles were associated with both the plasma membrane and the maturing face of dictyosomes. Dictyosome associated coated vesicles were smaller and had less distinct coats and vesicle membranes than those associated with the plasma membrane. Honeycomb structures believed to be aggregations of coats were also associated with the inner surface of the plasma membrane. Our data suggest that coated vesicles are produced by the Golgi apparatus, fuse with the plasma membrane, their coats remaining attached, at least temporarily, to the plasma membrane inner surface.

The extrarhabdomeral cytoskeleton in photoreceptors of Diptera. II. Plasmalemmal undercoats

1984 ◽  
Vol 220 (1220) ◽  
pp. 353-359 ◽  
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Genetic Analysis ◽  
Freeze Fracture ◽  
Integral Membrane Proteins ◽  
Basal Region ◽  
Thin Sections ◽  
En Face ◽  
Thiol Proteases ◽  
Planar Membranes

The plasmalemmal undercoats of those regions of the photoreceptors of the blowfly Lucilia that flank the central extracellular space of each ommatidium are described from en face and transverse thin sections. Labile structures were stabilized before fixation for electron microscopy by using an inhibitor of thiol proteases, Ep-475, as described in the previous paper (Blest et al., Proc. R. Soc. Lond . B 220, 339-352, 1984). Membranes of R 1-6 are underlain by a closely associated, randomly organized filamentous meshwork. That of the basal region of R 7 is highly organized, and consists of very long, about 8 nm filaments running parallel to each other and to the longitudinal ommatidial axis; these ‘backbone’ filaments are tightly adherent to the plasma membrane, and are spaced some 190-200 nm apart. They are linked by abundant transverse filaments that form a reticulum between them. The degree of ordering of the reticulum in life is not clear, but some well-preserved profiles suggest that it may be high. Replicas obtained by the freeze-fracture technique show that extrarhabdomeral membranes have dense populations of intramembrane particles, just as they do in Drosophila where a genetic analysis has shown them to consist largely of rhodopsin. It is proposed as a working hypothesis that these planar membranes can be regarded as flat equivalents of the microvillar membranes, that some fraction of the integral membrane proteins may be immobilized by bonding to the plasmalemmal undercoat, and that the latter may help to constrain both the translational and rotational movements of rhodopsin molecules.

Ultrastructural localization of nuclear antigens during interphase in mouse 3T3 fibroblasts

1989 ◽  
Vol 67 (9) ◽  
pp. 563-574 ◽  
Author(s):  
Nathalie Chaly ◽  
Gerald St. Aubin ◽  
David L. Brown
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Ultrastructural Localization ◽  
Nuclear Pores ◽  
Thin Sections ◽  
Nuclear Ultrastructure ◽  
3T3 Fibroblasts ◽  
Nuclear Antigens ◽  
Internal Component ◽  
Immunofluorescence Labelling

Thin sections of mouse 3T3 fibroblast nuclei labelled by immunoperoxidase with anti-nuclear antibodies I1, PI1, PI2, anti-peripherin, -lamin, and -centromere have been examined in the electron microscope. Staining was compared with the corresponding immunofluorescence labelling patterns, and was correlated with nuclear ultrastructure in conventionally fixed and uranyl-lead stained samples and in unlabelled immunoperoxidase controls. Peripherin was detected at the nuclear rim in a band broader and more irregular than the lamins/lamina. The peripheral components of PI1 and PI2 appear to be localized at nuclear pores and the nuclear envelope, respectively. The internal component of PI1 staining consisted of irregular patches and strands in the nucleoplasm, closely resembling snRNP staining as reported by others. Internal PI2 labelling consisted of spots distributed apparently at random in interchromatinic regions. The spots resembled labelling by antibody I1, but were fewer and more irregular in size. Neither the PI2 nor the I1 spots were centromere associated, nor could they be correlated with specific interchromatinic structures in conventional preparations and in unlabelled controls. The results support the hypothesis that the nucleus is segregated into function-specific domains, distinguished by morphology and (or) composition from surrounding regions of the nucleus.Key words: nuclear matrix, peripherin, immunoperoxidase, electron microscopy, nuclear antigens.

scholarly journals THE FINE STRUCTURE AND MODE OF ATTACHMENT OF THE SHEATHED FLAGELLUM OF VIBRIO METCHNIKOVII

1963 ◽  
Vol 18 (2) ◽  
pp. 327-336 ◽  
Author(s):  
Audrey M. Glauert ◽  
D. Kerridge ◽  
R. W. Horne
Keyword(s):  
Electron Microscopy ◽  
Cell Wall ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Thin Sections ◽  
Basal Disc ◽  
The Core ◽  
Thin Sectioning ◽  
Potassium Phosphotungstate ◽  
Mode Of Attachment

The sheathed flagellum of Vibrio metchnikovii was chosen for a study of the attachment of the flagellum to the bacterial cell. Normal and autolysed organisms and isolated flagella were studied by electron microscopy using the techniques of thin sectioning and negative staining. The sheath of the flagellum has the same layered structure as the cell wall of the bacterium, and in favourable thin sections it appears that the sheath is a continuation of the cell wall. After autolysis the sheath is usually absent and the core of the flagellum has a diameter of 120 A. Electron micrographs of autolysed bacteria negatively stained with potassium phosphotungstate show that the core ends in a basal disc just inside the plasma membrane. The basal disc is about 350 A in diameter and is thus considerably smaller than the "basal granules" described previously by other workers.

scholarly journals Adenosinetriphosphatase and 5-Nucleotidase Activities in the Plasma Membrane of Liver Cells as Revealed by Electron Microscopy

1958 ◽  
Vol 4 (6) ◽  
pp. 711-716 ◽  
Author(s):  
Edward Essner ◽  
Alex B. Novikoff ◽  
Bertha Masek
Keyword(s):  
Electron Microscopy ◽  
Plasma Membrane ◽  
Cell Surface ◽  
Cell Function ◽  
Molecular Transport ◽  
Enzyme Reaction ◽  
Bile Canaliculus ◽  
Nucleotidase Activity ◽  
Reaction Products ◽  
Thin Sections

The sites of reaction product resulting from ATPase and 5-nucleotidase activities remaining in parenchymatous cells of osmium-fixed rat liver were studied by electron microscopy of thin sections. These indicate that both ATPase and 5-nucleotidase activities are localized in the plasma membrane where it folds to form the microvilli of the bile canaliculus, and that 5-nucleotidase activity is also present in the microvilli at the sinusoidal aspects of the cells. It is suggested that these enzymes, particularly ATPase, may play a role in molecular transport or in some kind of membrane activity at the cell surface. Of special interest is the apparent differential localization of these enzymes at the absorptive and secretory regions of the plasma membrane of the cell. It may be of interest to study changes in these enzyme localizations in pathologic states, as a sign of changed cell function. Some of the difficulties in the interpretation of enzyme reaction products seen in electron micrographs are discussed.

Two- or three-way observations of the identical cell elements within the same sections by LM, TEM and/or SEM

1978 ◽  
Vol 36 (2) ◽  
pp. 82-83 ◽  
Author(s):  
Nakazo Watari ◽  
Yasuaki Hotta ◽  
Yoshio Mabuchi
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Fine Structure ◽  
Light Microscopy ◽  
Thin Sections ◽  
Transmission Electron ◽  
Identical Cell ◽  
Electron Microscopes ◽  
Scanning Electron

It is very useful if we can observe the identical cell elements within the same sections by light microscopy (LM), transmission electron microscopy (TEM) and/or scanning electron microscopy (SEM) sequentially, because, the cell fine structure can not be indicated by LM, while the color is; on the other hand, the cell fine structure can be very easily observed by EM, although its color properties may not. However, there is one problem in that LM requires thick sections of over 1 μm, while EM needs very thin sections of under 100 nm. Recently, we have developed a new method to observe the same cell elements within the same plastic sections using both light and transmission (conventional or high-voltage) electron microscopes.In this paper, we have developed two new observation methods for the identical cell elements within the same sections, both plastic-embedded and paraffin-embedded, using light microscopy, transmission electron microscopy and/or scanning electron microscopy (Fig. 1).

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