scholarly journals Intercellular junctions, intramembranous particles and cytoskeletal elements of deep cells of the Fundulus gastrula

Development ◽  
1977 ◽  
Vol 40 (1) ◽  
pp. 125-141
Author(s):  
James Hogan ◽  
J. P. Trinkaus
Keyword(s):  
Electron Microscopy ◽  
Plasma Membranes ◽  
Intercellular Junctions ◽  
Gastrula Stage ◽  
Intramembranous Particles ◽  
Transmission Electron ◽  
Locomotory Behavior ◽  
Thin Sectioning ◽  
Cytoplasmic Microtubules ◽  
Cytoskeletal Elements

The fine structure of motile deep cells of the gastrula stage of Fundulus hetewclitus was studied with transmission electron microscopy, using both thin sectioning and freeze-cleave techniques. Gastrula deep cells form extensive non-junctional appositions with each other, in which the apposed plasma membranes are parallel and separated by a distance of 26–28 nm. They also form gap junctions. Tight junctions, desmosomes, and extensive interdigitations of apposed plasma membranes were not observed. The plasma membranes of deep cells contain numerous unclustered intramembranous particles. Cytoplasmic microtubules were found, but they appear to be small in number, sparsely distributed, and mainly randomly oriented. Microfilaments are also present and are localized largely in the cortical cytoplasm and in thin cell extensions. The significance of these findings for the contact and locomotory behavior of deep cells is discussed.

Ultrastructure of sheep erythrocyte plasma membranes and cytoskeletons bound to solid supports

1981 ◽  
Vol 49 (1) ◽  
pp. 383-399
Author(s):  
R.D. Lang ◽  
M.V. Nermut ◽  
L.D. Williams
Keyword(s):  
Electron Microscopy ◽  
Plasma Membranes ◽  
Sheep Erythrocyte ◽  
Alkaline Treatment ◽  
Whole Cells ◽  
Intramembranous Particles ◽  
Transmission Electron ◽  
Protein Components ◽  
Triton X ◽  
Positively Charged

Sheep erythrocyte plasma membrane monolayers were formed on positively charged supports by means of controlled lysis and squirting of cells so that the original protoplasmic or inner surfaces (PS) were exposed. The appearance of the surface was studied by transmission electron microscopy of platinum/carbon replicas following freeze-drying of the membranes. After gentle washing with water or dilute buffer, a network of filaments and particles was found to cover the surface. Whole cells bound to positively charged supports were treated with Triton X-100 and hypertonic KCl, which left the protein components of the cytoskeleton on the support. Stereo electron microscopy of Pt/C replicas of these residues showed complex networks of filaments, similar to those seen on the cytoplasmic surfaces of the intact membranes. In both cases the lengths of the filaments correspond to that of the spectrin dimer. Removal of spectrin, actin and other proteins by alkaline treatment led to loss of this network and revealed 15.4-nm particles on the membranes PS. These particles, which were also visible after negative staining, could be removed by treatment with trypsin and were found to correspond to band 4 protein (the equivalent of human erythrocyte band 3 protein). Membranes freeze-fractured following treatment with alkali showed normal intramembranous particles with frequencies similar to those of native membranes. This indicates that band 4 protein spans the sheep erythrocyte membrane and forms a very high proportion of the intramembranous particles. The protoplasmic portions of these particles may be membrane binding sites for the cytoskeleton in sheep erythrocytes.

Intercellular junctions in the larval epidermis of the colonial ascidian Distaplia occidentalis: a thin-section and freeze-fracture examination

1986 ◽  
Vol 64 (1) ◽  
pp. 112-117 ◽  
Author(s):  
Michael J. Cavey ◽  
Richard L. Wood
Keyword(s):  
Electron Microscopy ◽  
Freeze Fracture ◽  
Intercellular Junctions ◽  
Epidermal Cells ◽  
Cellular Membranes ◽  
Colonial Ascidian ◽  
Thin Sections ◽  
Intramembranous Particles ◽  
Transmission Electron ◽  
Columnar Cells

The larval epidermis of the colonial ascidian Distaplia occidentalis is a unilayered epithelium consisting of squamous and cuboidal or low columnar cells. The epidermal cells are laterally folded and interdigitated or overlapped. The occluding (tight) junctions and the close (gap) junctions that join the epidermal cells have been examined by transmission electron microscopy. In thin sections, the occluding junction is represented by focal fusions of the apposed plasmalemmata. Freeze-fracture replicas of the occluding junction show linear, anastomosing arrays of intramembranous particles on the protoplasmic faces of the cellular membranes. In thin sections of the close junction, the apposed plasmalemmata are mutually parallel and separated by a narrow intercellular cleft. Freeze-fracture replicas of the close junction reveal macular aggregations of intramembranous particles on the protoplasmic faces of the cellular membranes.

scholarly journals Embryonic development in Zungaro jahu

Zygote ◽  
2016 ◽  
Vol 25 (1) ◽  
pp. 17-31 ◽  
Author(s):  
Camila Marques ◽  
Francine Faustino ◽  
Bruno Bertolucci ◽  
Maria do Carmo Faria Paes ◽  
Regiane Cristina da Silva ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Embryonic Development ◽  
Egg Cell ◽  
Gastrula Stage ◽  
Transmission Electron ◽  
Larval Hatching ◽  
Morula Stage ◽  
Zygote Stage ◽  
Scanning Electron

SummaryThe aim of this study was to characterize the embryonic development of Zungaro jahu, a fresh water teleostei commonly known as ‘jaú’. Samples were collected at pre-determined times from oocyte release to larval hatching and analysed under light microscopy, transmission electron microscopy and scanning electron microscopy. At the first collection times, the oocytes and eggs were spherical and yellowish, with an evident micropyle. Embryo development took place at 29.4 ± 1.5°C and was divided into seven stages: zygote, cleavage, morula, blastula, gastrula, organogenesis, and hatching. The differentiation of the animal and vegetative poles occured during the zygote stage, at 10 min post-fertilization (mpf), leading to the development of the egg cell at 15 mpf. From 20 to 75 mpf, successive cleavages resulted in the formation of 2, 4, 8, 16, 32 and 64 blastomeres. The morula stage was observed between 90 and 105 mpf, and the blastula and gastrula stage at 120 and 180 mpf; respectively. The end of the gastrula stage was characterized by the presence of the yolk plug at 360 mpf. Organogenesis followed, with differentiation of the cephalic and caudal regions, elongation of the embryo by the cephalo-caudal axis, and somitogenesis. Hatching occurred at 780 mpf, with mean larval total length of 3.79 ± 0.11 mm.

Detection of Graphene Materials in Fibers

2020 ◽  
Vol 976 ◽  
pp. 90-95
Author(s):  
Wei Dong Li ◽  
Ton Gjun Ma ◽  
Zhi Ping Mao
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Resolution ◽  
Elemental Composition ◽  
Energy Dispersive Spectroscopy ◽  
Number Of Layers ◽  
Sectioning Method ◽  
Transmission Electron ◽  
Thin Sectioning ◽  
Graphene Material

A method for the identification of graphene materials in fibers by high-resolution transmission electron microscopy (HRTEM)-Energy Dispersive Spectroscopy (EDS) has been reported. Two ways to prepare samples are available, namely the dissolution extraction and the ultra-thin sectioning method. For samples prepared by any method, the graphene material in the fiber can be detected by the following steps. Firstly,the elemental composition of the microparticle is demonstrated by EDS. Secondly, the morphology of the particles in the fiber can be obtained by TEM, and the number of layers of graphene materials is able to observed directly from the edge of sheet.

Development of cell wall modifications in the endodermis and exodermis of Allium cepa roots

2001 ◽  
Vol 79 (5) ◽  
pp. 621-634 ◽  
Author(s):  
Fengshan Ma ◽  
Carol A Peterson
Keyword(s):  
Electron Microscopy ◽  
Allium Cepa ◽  
Plasma Membranes ◽  
Casparian Bands ◽  
Transmission Electron ◽  
Allium Cepa L ◽  
Suberin Lamellae ◽  
Pit Field ◽  
Casparian Band ◽  
Suberin Lamella

The cytological events of wall modification in the endodermis and exodermis of Allium cepa L. roots were examined with fluorescence and transmission electron microscopy. In the endodermis, Casparian bands, suberin lamellae, and tertiary walls developed in succession. At the site of the future Casparian band, the plasma membrane was bound to the wall before deposition of detectable hydrophobic components in the radial wall. Suberin lamellae were deposited on the inner faces of the primary walls, first along the outer tangential walls and then the inner tangential walls. On both walls, segments of the lamellae were formed earlier in primary pit fields than at nonprimary pit field regions. Suberin lamellae then extended to the radial walls. When they reached the Casparian bands, the lamellae intruded between the bound plasma membranes and the walls, so that the cells' plasma membranes remained intact. In this way, suberin lamellae that were continuous around the cells were laid down. Later, tertiary walls were deposited internal to the suberin lamellae. None of the wall modifications interrupted the symplastic connections of the endodermis. During suberin lamella and tertiary wall formation, more dictyosomes and ER profiles appeared than during Casparian band development. In the exodermis, although Casparian bands were readily detected with fluorescence microscopy, they were rarely detected with electron microscopy. Suberin lamellae were formed in long cells severing their plasmodesmata. As in the endodermis, dictyosomes and ER were prominent during suberin lamella formation. Tertiary walls were not formed in the exodermis.Key words: Allium cepa, Casparian band, endodermis, exodermis, suberin lamella, ultrastructure.

Structural and textural changes from polyimide Kapton to graphite: Part I. Optical microscopy and transmission electron microscopy

1992 ◽  
Vol 7 (5) ◽  
pp. 1158-1173 ◽  
Author(s):  
C. Bourgerette ◽  
A. Oberlin ◽  
M. Inagaki
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Optical Microscopy ◽  
Film Plane ◽  
Transmission Electron ◽  
Heat Treated ◽  
Thin Sectioning ◽  
Embedded Blocks ◽  
Textural Changes ◽  
Graphite Part

Kapton films, 25 μm thick, were carbonized and then graphitized at various temperatures up to 3000 °C. They were studied by optical microscopy and transmission electron microscopy and were prepared by thin-sectioning for transmission electron microscopy. The residual embedded blocks were used as polished sections for optical microscopy. Kapton thin film heat-treated at 650 °C showed thin areas of preferred orientation at its two opposite faces. This orientation extends all over the film thickness between 800 °C and 1000 °C. It corresponds to a statistical orientation of small aromatic layer stacks, parallel to the film plane. From 1000 °C up to 2475 °C flattened pores develop everywhere. At 2475 °C, they suddenly collapse and partial graphitization occurs. The Kapton film is completely graphitized between 2820 °C and 3000 °C. The mechanism of graphitization is similar to that of anthracites and also to that of nongraphitizing carbons heat-treated under pressure.

Motile microtubles in foraminifera: Correlative video-enhanced contrast light and transmission electron microscopy

1988 ◽  
Vol 46 ◽  
pp. 116-117
Author(s):  
J.L. Travis ◽  
S.S. Bowser
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Model Systems ◽  
Surface Transport ◽  
Transmission Electron ◽  
Contrast Enhanced ◽  
Video Microscope ◽  
Subcellular Processes ◽  
Cytoplasmic Microtubules

Analog and digital contrast-enhanced video light microscopy have provided exciting new views of subcellular architecture and dynamics. One such example is recent work on the motility of the pseudopodia of Allogromia and other foraminifera. Because of the unsurpassed clarity with which their cytoplasmic microtubules can be visualized, these organisms have been used extensively as model systems in which to study microtubule- associated cell motility in vivo. We have employed correlative electron microscopy to further resolve the subcellular processes imaged by the video microscope. Our studies indicate that the bidirectional axial and lateral movements of cytoplasmic microtubules drives the formation and movement of the pseudopodia. Furthermore, organelle and cell surface transport occur exclusively along the motile microtubules.The exceptional visibility of foraminiferan microtubules in vivo is due to the fact that when the organisms are plated on cationized substrates, the normally cylindrical pseudopodia spread along the substrate and become highly flattened (generally to a thickness of ≤ 0.5μm).

Thin sectioning for cryo transmission electron microscopy (cryo TEM)

1986 ◽  
Vol 44 ◽  
pp. 102-103
Author(s):  
A.W. McDowall ◽  
J.M. Smith ◽  
J. Dubochet
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Microscope ◽  
Structural Integrity ◽  
Specimen Preparation ◽  
Structural Alterations ◽  
Whole Cells ◽  
Transmission Electron ◽  
Thin Sectioning

Processing whole cells and tissues for conventional TEM is known to cause structural alterations. Much effort has been devoted, therefore, to developing techniques which avoid specimen preparation artefacts. Recently, research using a cryo-electron microscope has shown that biological suspensions embedded in vitreous ice retain their structural integrity, and when compared with conventionally prepared TEM specimens, are free from many of the classical artefacts. In order to extend the advantage of cryo TEM to whole cells and tissues, we have developed a method of thin sectioning vitrified material.

Extracellular microtubules in aphid gut

1994 ◽  
Vol 52 ◽  
pp. 198-199
Author(s):  
R. Witkus ◽  
M. Griffin ◽  
L. Jacobs ◽  
D. Bolkhovets ◽  
G. M. Vernon
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Green Peach Aphid ◽  
Anterior Part ◽  
Single Layer ◽  
Pea Aphid ◽  
True Nature ◽  
Transmission Electron ◽  
Green Pea ◽  
Cytoplasmic Microtubules

The presence of extracellular microtubules on the microvillar surface of the intestine of a number of aphids was noted as early as 1972. The authors stated, “At present there is little evidence as to the true nature of these extracellular microtubules. We have used the term microtubule in the broad sense.” These microtubules are smaller than cytoplasmic microtubules reported earlier.In the present investigation we have studied the intestinal epithelium of the green pea aphid, A. pisum, using transmission electron microscopy. The epithelium consists of a single layer of pyramidal shaped cells with a striated border. In the anterior part of the intestine the striated border consists of a microlabyrinth (Fig. 1) similar to that previously described for the green peach aphid, Myzus persicae. In some regions of the microlabyrinth the microtubules are arranged at right angles to the length of the infoldings; in other regions microtubules run parallel to the length of the infoldings giving support to this structure.

scholarly journals High Voltage Microscopy in Paleontological Studies – Graptolites

1970 ◽  
Vol 28 ◽  
pp. 492-493
Author(s):  
W. B. N. Berry ◽  
R. S. Takagi ◽  
G. Thomas ◽  
D. J. Jurica
Keyword(s):  
Electron Microscopy ◽  
High Voltage ◽  
The Other ◽  
Transmission Power ◽  
High Voltage Electron Microscopy ◽  
Voltage Electron ◽  
Transmission Electron ◽  
Thin Sectioning ◽  
Electron Microscopes ◽  
Biological Methods

Transmission electron microscopy has seldom been used in studies of fossils, and to date, no electron diffraction work has been reported. Because of the limited transmission power of the 100 kV electron microscopes (<lμ), the techniques which have been used to prepare specimens have followed standard biological methods, including ultra-thin sectioning and staining. High voltage electron microscopy on the other hand allows examination of considerably thicker specimens (up to 5μ at 500 kV) and is particularly useful in studying fossils e.g. it is often not necessary to section pieces of the fossil. Minimal preparation is advantageous because materials that have been interred in rocks of the earth's crust for millions of years are commonly brittle and distort or break while being sectioned with the microtome.

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