scholarly journals Cytoplasmic structure in rapid-frozen axons.

1982 ◽  
Vol 94 (3) ◽  
pp. 667-669 ◽  
Author(s):  
B J Schnapp ◽  
T S Reese
Keyword(s):  
Multivesicular Bodies ◽  
Axonal Membrane ◽  
Thin Sections ◽  
Cytoplasmic Structure ◽  
Axonal Cytoskeleton ◽  
Inner Surface ◽  
Living State ◽  
Granular Matrix ◽  
Axoplasmic Reticulum ◽  
Characteristic Relationship

Turtle optic nerves were rapid-frozen from the living state, fractured, etched, and rotary shadowed. Stereo views of fractured axons show that axoplasm consists of three types of longitudinally oriented domains. One type consists of neurofilament bundles in which individual filaments are interconnected by a cross-bridging network. Contiguous to neurofilament domains are domains containing microtubules suspended in a loose, granular matrix. A third domain is confined to a zone, 80-100 nm wide, next to the axonal membrane and consists of a dense filamentous network connecting the longitudinal elements of the axonal cytoskeleton to particles on the inner surface of the axolemma. Three classes of membrane-limited organelles are distinguished: axoplasmic reticulum, mitochondria, and discrete vesicular organelles. The vesicular organelles must include lysosomes, multivesicular bodies, and vesicles which are retrogradely transported in axons, though some vesicular organelles may be components of the axoplasmic reticulum. Organelles in each class have a characteristic relationship to the axonal cytoskeleton. The axoplasmic reticulum enters all three domains of axoplasm, but mitochondria and vesicular organelles are excluded from the neurofilament bundles, a distribution confirmed in thin sections of cryoembedded axons. Vesicular organelles differ from mitochondria in at least three ways with respect to their relationships to adjacent axoplasm: (a) one, or sometimes both, of their ends are associated with a gap in the surrounding granular axoplasm; (b) an appendage is typically associated with one of their ends; and (c) they are not attached or closely apposed to microtubules. Mitochondria, on the other hand, are only rarely associated with gaps in the axoplasm, do not have an appendage, and are virtually always attached to one or more microtubules by an irregular array of side-arms. We propose that the longitudinally oriented microtubule domains are channels within which organelles are transported. We also propose that the granular material in these channels may constitute the myriad enzymes and other nonfibrous components that slowly move down the axon.

Polymorphous endocytotic organelles in the receptor-mediated endocytosis of gold-labelled alpha 2-macroglobulin complexes by human fibroblasts

1985 ◽  
Vol 75 (1) ◽  
pp. 411-421
Author(s):  
B. Van der Schueren ◽  
D. Gasser ◽  
P. Marynen ◽  
F. Van Leuven ◽  
G. David ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Endoplasmic Reticulum ◽  
Human Fibroblasts ◽  
Cellular Structures ◽  
Multivesicular Bodies ◽  
Staining Reaction ◽  
Human Skin Fibroblasts ◽  
Thin Sections ◽  
Receptor Mediated Endocytosis ◽  
Gold Label

The receptor-mediated endocytosis of gold-labelled alpha 2-macroglobulin complexes with trypsin or methylamine (alpha 2M-T-Au or alpha 2M-MA-Au) was studied by electron microscopy in human skin fibroblasts. The gold label was found in coated structures and very small tubules as well as in tubulovesicular structures and in multivesicular bodies/lysosomes. Thick sections (200 nm), but especially serial thin sections, clearly showed the polymorphic character of the cellular structures involved in endocytosis. Numerous intercommunications were particularly obvious between the tubulovesicular structures, the larger vesicles and the multivesicular bodies (MVB). Continuities between MVBs and endoplasmic reticulum and interconnections between MVBs were also observed. The specificity of the staining reaction was confirmed by indirect labelling of intracellular alpha 2M by polyclonal and by monoclonal antibodies on ultracryosections. These findings are discussed in relation to observations made on epithelial cells with other ligands.

scholarly journals THE ULTRASTRUCTURE OF A MAMMALIAN CELL DURING THE MITOTIC CYCLE

1964 ◽  
Vol 21 (3) ◽  
pp. 429-463 ◽  
Author(s):  
Elliott Robbins ◽  
Nicholas K. Gonatas
Keyword(s):  
Nuclear Envelope ◽  
Nuclear Membrane ◽  
Mitotic Cycle ◽  
Mitotic Cell ◽  
Multivesicular Bodies ◽  
Chromosome Movement ◽  
Living State ◽  
Characteristic Points ◽  
Circumferential Distribution ◽  
Selection Of

With a technique of preselecting the mitotic cell in the living state for subsequent electron microscopy, it has been possible to examine the ultrastructure of the various stages of mitosis with greater precision than has been reported previously. The early dissolution of the nuclear envelope has been found to be preceded by a marked undulation of this structure within the nuclear "hof." This undulation appears to be intimately related to the spindle-forming activity of the centriole at this time. Marked pericentriolar osmiophilia and extensive arrays of vesicles are also prominent at this stage, the former continuing into anaphase. Progression of the cell through prophase is accompanied by a disappearance of these vesicles. A complex that first makes its appearance in prophase but becomes most prominent in metaphase is a partially membrane-bounded cluster of dense osmiophilic bodies. These clusters which have a circumferential distribution in the mitotic cell are shown to be derived from multivesicular bodies and are acid phosphatase-positive. The precise selection of cells during the various stages of anaphase has made it possible to follow chronologically the morphological features of the initiation of nuclear membrane reformation. The nuclear membrane appears to be derived from polar aggregates of endoplasmic reticulum, and the process begins less than 2 minutes after the onset of karyokinesis. While formation of the nuclear envelope is initiated on the polar aspects of the chromatin mass, envelope elements appear on the equatorial aspect long before the polar elements fuse. Apparently interfering with this fusion are continuous spindle tubules which traverse the chromatin mass in striking density at characteristic points. Several cortical changes, also most pronounced in anaphase, have been described, as has the kinetochore which is seen to good advantage only in this stage. The Golgi complex has been found to disappear both morphologically and histochemically during mitosis and to reappear rapidly in telophase. Evidence is presented which implicates the continuous spindle tubules in certain phases of chromosome movement.

scholarly journals A CYTOCHEMICAL LOCALIZATION OF REDUCTIVE SITES IN A GRAM-NEGATIVE BACTERIUM

1964 ◽  
Vol 20 (3) ◽  
pp. 377-387 ◽  
Author(s):  
Woutera van Iterson ◽  
W. Leene
Keyword(s):  
Plasma Membrane ◽  
Electron Scattering ◽  
Gram Negative Bacteria ◽  
Proteus Vulgaris ◽  
Electron Microscopic ◽  
Cytochemical Localization ◽  
Gram Negative ◽  
Living State ◽  
Granular Matrix ◽  
Reducing Activity

In order to obtain information on the exact location of the respiratory enzyme chain in Gram-negative bacteria, an electron microscopic study was made of the sites of reducing activity of cells that had, in the living state, incorporated tellurite. In the test object Proteus vulgaris, the reduced tellurite was found to be deposited in bodies contiguous with the plasma membrane but different in structure from those described in the Gram-positive Bacillus subtilis (2). In fact, the bodies proved to consist of a conglomerate of elements which contained the strongly electron-scattering reduced tellurite and a delicately granular "matrix." A limiting membrane was not observed around these complexes. In serial sections details of the complexes are illustrated. Reduced tellurite was not deposited in the plasma membrane to any important degree. Since no other sites of deposition of the reduced product were revealed, it is assumed that the complexes represent the mitochondrial equivalents in the investigated organism. In addition, the bodies might function as the basal granules of the flagella.

scholarly journals The Fine Structure of Streptomyces coelicolor

1960 ◽  
Vol 7 (3) ◽  
pp. 479-487 ◽  
Author(s):  
Audrey M. Glauert ◽  
David A. Hopwood
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Fine Structure ◽  
Streptomyces Coelicolor ◽  
Nuclear Material ◽  
Tubular Structures ◽  
Thin Sections ◽  
Cytoplasmic Structure ◽  
Intracytoplasmic Membranes ◽  
Membranous Component

Colonies and spore suspensions of Streptomyces coelicolor were fixed by the method of Kellenberger, Ryter, and Séchaud (1958) and embedded in methacrylate or araldite. Thin sections were cut with an A. F. Huxley microtome and examined in a Siemens' Elmiskop I. At all stages of development the hyphae of Streptomyces coelicolor have an extensive membranous component in the cytoplasm. The membranes are continuous with the plasma membrane and have a variety of configurations at different places in the hyphae. Tubular structures, vesicles, and parallel stacks of membranes are seen. In some areas concentric layers of membranes form whorled structures which are particularly frequent in the region of developing cross-walls and within maturing spores. In the spores membranous structures often lie embedded in the nuclear material. In disintegrating hyphae the intracytoplasmic membranes round off into small vesicles and remain when the rest of the cytoplasmic structure has gone. In the absence of typical mitochondria and other cytoplasmic membranous structures it is possible that the membranous component of the cytoplasm of Streptomyces coelicolor may perform the functions of the endoplasmic reticulum and/or the mitochondria of higher cells.

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.

scholarly journals LEBENDNACHWEIS VON EINZELELEMENTEN DES ENDOPLASMATISCHEN RETIKULUMS

1965 ◽  
Vol 27 (2) ◽  
pp. 433-440 ◽  
Author(s):  
Manfred Girbardt
Keyword(s):  
Electron Microscopy ◽  
Phase Contrast ◽  
Preparation Technique ◽  
Phase Contrast Microscopy ◽  
Membrane Systems ◽  
Thin Sections ◽  
Living State ◽  
Contrast Microscopy ◽  
Cell Components ◽  
A Cell

By means of a special selective preparation technique, it is possible to investigate in thin sections, by electron microscopy, areas of a cell that have been observed in the living state, by phase-contrast microscopy, up to the time of fixation. Structures recorded in the living state can thus be compared to structures seen in electron micrographs. In cells of the fungus Polystictus versicolor, aggregates of membrane systems as well as single cisternae with a diameter of approximately 200 to 300 A can be detected with phase optics. It can be shown, by calculation, that these structures, which are far below the limit of resolution of the light optical system, give enough contrast to be discernible by phase optics. Thus a basis is provided for observing the dynamics of membrane systems which perhaps may contribute to the analysis of the functional significance of these cell components.

scholarly journals Immunocytochemical localization of the major surfactant apoproteins in type II cells, Clara cells, and alveolar macrophages of rat lung.

1986 ◽  
Vol 34 (9) ◽  
pp. 1137-1148 ◽  
Author(s):  
S R Walker ◽  
M C Williams ◽  
B Benson
Keyword(s):  
Alveolar Macrophages ◽  
Lamellar Body ◽  
Alveolar Type ◽  
Multivesicular Bodies ◽  
Type Ii Cells ◽  
Type Ii ◽  
Clara Cells ◽  
Rat Lung ◽  
Lamellar Bodies ◽  
Thin Sections

The adsorptive properties of phospholipids of pulmonary surfactant are markedly influenced by the presence of three related proteins (26-38 KD, reduced) found in purified surfactant. Whether these proteins are pre-assembled with lipids before secretion is uncertain but would be expected for a lipoprotein secretion. We performed indirect immunocytochemistry on frozen thin sections of rat lung to identify cells and intracellular organelles that contain these proteins. The three proteins, purified from lavaged surfactant, were used to generate antisera in rabbits. Immunoblotting of rat surfactant showed that the IgG reacted with the three proteins and a 55-60 KD band which may be a polymer of the lower MW species. Specific gold labeling occurred over alveolar type II cells, bronchiolar Clara cells, alveolar macrophages, and tubular myelin. In type II cells labeling occurred in synthetic organelles and lamellar bodies, which contain surfactant lipids. Lamellar body labeling was increased fivefold by pre-treating tissue sections with a detergent. Multivesicular bodies and some small apical vesicles in type II cells were also labeled. Secondary lysosomes of alveolar macrophages were immunoreactive. Labeling in Clara cells exceeded that of type II cells, with prominent labeling in secretory granules, Golgi apparatus, and endoplasmic reticulum. These observations clarify the organelles and pathways utilized in the elaboration of surfactant. After synthesis, the proteins move, probably via multivesicular bodies, to lamellar bodies. Both lipids and proteins are present in tubular myelin. Immunologically identical or closely similar proteins are synthesized by Clara cells and secreted from granules which appear not to contain lipid. The role of these proteins in bronchiolar function is unknown.

Subplasmalemmal Microfilaments and Microtubules in Cultivated Macrophages

1972 ◽  
Vol 30 ◽  
pp. 246-247
Author(s):  
E.P. Reaven ◽  
S.G. Axline
Keyword(s):  
Intracellular Transport ◽  
Cytochalasin B ◽  
Cell Movement ◽  
Peritoneal Macrophages ◽  
Membrane Translocation ◽  
Thin Sections ◽  
Inner Surface ◽  
Mediate Cell ◽  
Mouse Peritoneal Macrophages

Recent studies suggest that contractile microfilaments and/or microtubules may mediate cell movement and intracellular transport of cytoplasmic constituents. Current studies of control, phagocytizing and cytochalasin B (CB) treated macrophages provide evidence that membrane translocation required for endocytosis may involve similar mechanisms.Mouse peritoneal macrophages, cultivated for 48 hours, were fixed and embedded directly on glass coverslips to preserve the original orientation of the monolayers. Analysis of serial thin sections cut parallel to the plane of glass attachment disclosed a number of features of the cells not previously described.1) A loose, delicate, continuous network of 40-50 Å microfilaments extending from the inner surface of the plasmalemma to a depth of 500-600 Å were found in all regions of the cell (Fig. 1). In areas of normal pseudopodal folding or retraction, the network was thickened and of increased density. The filaments of this network were insensitive to CB treatment (5-10 μg/ml).

A Note on the Fine Structure of a Spirochaete

1963 ◽  
Vol s3-104 (65) ◽  
pp. 145-153
Author(s):  
A. V. GRIMSTONE
Keyword(s):  
Fine Structure ◽  
Cell Body ◽  
Thin Membrane ◽  
Thin Sections ◽  
Bacterial Flagella ◽  
Resolution Electron ◽  
Inner Surface ◽  
Unknown Composition ◽  
Cryptocercus Punctulatus ◽  
High Resolution Electron Micrographs

A description is given, based on high-resolution electron micrographs of thin sections, of the structure of a spirochaete from the gut of a cockroach, Cryptocercus punctulatus. There is a central cell-body, the structure of which resembles that of a bacterium. Two kinds of granule are abundant in the cell-body: large ones, 150 to 250 A in diameter, of unknown composition, and small ones, identified as ribosomes, which may be arranged in whorls on the inner surface of the bounding membrane. Numerous small chromatin bodies are present. The bounding membrane of the cell-body is complex in structure. The cell-body is loosely enveloped by a sheath, made up of a thin membrane supporting a coarsely filamentous outer layer. In the space between sheath and cell-body is a loose bundle of 60 to 100 fibres. These are 140 A in diameter and are coiled helically around the cell-body. They resemble bacterial flagella and are thought to be responsible for the movements of the organism.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

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