scholarly journals Terminal phase of cytokinesis in D-98S cells

1977 ◽  
Vol 73 (3) ◽  
pp. 672-684 ◽  
Author(s):  
J Mullins ◽  
JJ Biesele
Keyword(s):  
Electron Microscopy ◽  
Significant Contribution ◽  
Light And Electron Microscopy ◽  
Time Lapse ◽  
Nuclear Material ◽  
Terminal Phase ◽  
Serial Sectioning ◽  
Intercellular Bridge ◽  
Daughter Cells ◽  
Complete Breakdown

The events leading to the completion of cytokinesis after the formation of the midbody and intercellular bridge in D-98S cells were studied with light and electron microscopy. Pairs of daughter cells corresponding to different stages of cytokineses, as determined previously form time lapse films, were selected from embedded monolayers for serial sectioning. Separation of daughter cells is preceded by the reduction in diameter of the intercellular bridge from 1-1.5 μm to approx. 0.2 μm. Two processes contribute to this reduction: (a) The intercellular bridge becomes gradually thinner after telophase; a progressive breakdown of midbody structures accompanies this change; and (b) the more significant contribution to reduction in bridge diameter occurs through the localized constriction of a segment of the intercellular bridge.. The microtubules within the constricted portion of the bridge are forced closer together, and some microtubules disappear as this narrowing progresses. The plasma membrane over the narrowed segments is thrown into a series of wavelike ripples. Separation of daughter cells is achieved through movements of the cells which stretch and break the diameter-reduced bridge. The midbody is discarded after separation and begins to deteriorate. Occasional pairs of daughter cells were found in which incomplete karyokineses resulted in their nuclei being connected by a strand of nuclear material traversing the bridge and midbody. Such cells do not complete cytokinesis but merge together several hours after telophase. This merging of daughter cells coincides with the nearly complete breakdown of the midbody.

scholarly journals The absence of centrioles from spindle poles of rat kangaroo (PtK2) cells undergoing meiotic-like reduction division in vitro.

1977 ◽  
Vol 72 (2) ◽  
pp. 368-379 ◽  
Author(s):  
S Brenner ◽  
A Branch ◽  
S Meredith ◽  
M W Berns
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Time Lapse ◽  
Spindle Pole ◽  
Reduction Division ◽  
Daughter Cells ◽  
Spindle Poles ◽  
Spindle Apparatus ◽  
Time Lapse Photography

Light and electron microscopy were used to study somatic cell reduction division occurring spontaneously in tetraploid populations of rat kangaroo Potorous tridactylis (PtK2) cells in vitro. Light microscopy coupled with time-lapse photography documented the pattern of reduction division which includes an anaphase-like movement of double chromatid chromosomes to opposite spindle poles followed by the organization of two separate metaphase plates and synchronous anaphase division to form four poles and four daughter nuclei. The resulting daughter cells were isolated and cloned, showing their viability, and karyotyped to determine their ploidy. Ultrastructural analysis of cells undergoing reduction consistently revealed two duplexes of centrioles (one at each of two spindle poles) and two spindle poles in each cell that lacked centrioles but with microtubules terminating in a pericentriolar-like cloud of material. These results suggest that the centriole is not essential for spindle pole formation and division and implicate the could region as a necessary component of the spindle apparatus.

Morphogenesis of arthroconidiation in the dermatophyte Trichophyton mentagrophytes with special reference to wall ontogeny

1984 ◽  
Vol 30 (11) ◽  
pp. 1415-1421 ◽  
Author(s):  
Tadayo Hashimoto ◽  
R. G. Emyanitoff ◽  
R. C. Mock ◽  
J. H. Pollack
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Trichophyton Mentagrophytes ◽  
Outer Wall ◽  
Time Lapse ◽  
Wall Layer ◽  
Spore Surface ◽  
Inner Surface ◽  
Initial Sign ◽  
Hyphal Wall

The formation of arthroconidia, especially the ontogeny of the arthroconidial wall in the dermatophyte Trichophyton mentagrophytes, was investigated by light and electron microscopy. Time-lapse photomicroscopy revealed that the new septa were inserted regularly along the length of the hypha. Each new septum divided a preexisting hyphal segment into approximately equal halves. The initial sign of arthroconidium formation detected by electron microscopy was the deposition of a conidium-specific wall layer on the inner surface of the preexisting hyphal wall. The invaginating septal material was continuous with the newly deposited inner wall layer of the sporulating hyphae. When septation was completed, the septum and septal furrow were continuous across the wall to the inner edge of the outer wall layer. After septation, the inner wall continued to thicken until it attained the thickness of a mature arthroconidial wall (0.3 – 0.5 μm). Simultaneously, immature arthroconidia continued to swell and eventually assumed a barrel shape. When disarticulated, arthroconidia were surrounded by the newly formed conidial wall at the poles, and the sides of the conidia were additionally bounded by the residual hyphal wall. As the arthroconidia matured, the remnants of the hyphal wall tended to be detached from the spore surface. From these observations we conclude that T. mentagrophytes formed arthroconidia by the enteroarthric mode rather than the holoarthric process as previously described.

scholarly journals Multiscale ATUM-FIB microscopy enables targeted ultrastructural analysis at isotropic resolution

2020 ◽  
Author(s):  
Georg Kislinger ◽  
Helmut Gnägi ◽  
Martin Kerschensteiner ◽  
Mikael Simons ◽  
Thomas Misgeld ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Ion Beam ◽  
Light And Electron Microscopy ◽  
Three Dimensional ◽  
Biological Tissues ◽  
Ultrastructural Analysis ◽  
Serial Sectioning ◽  
Isotropic Resolution ◽  
High Resolution Analysis ◽  
3D Information

AbstractVolume electron microscopy enables the ultrastructural analysis of biological tissues and is essential for dense reconstructions e.g. of neuronal circuits. So far, three-dimensional analysis is based on either serial sectioning followed by sequential imaging (ATUM, ssTEM/SEM) or serial block-face imaging (SB-SEM, FIB-SEM), where imaging is intercalated with sectioning. Currently, the techniques involving ultramicrotomy allow scanning large fields of view, but afford only limited z-resolution determined by section thickness, while ion beam-milling approaches yield isotropic voxels, but are restricted in volume size. Now we present a hybrid method, named ATUM-FIB, which combines the advantages of both approaches: ATUM-FIB is based on serial sectioning of tissue into semithick (2-10 µm) resin sections that are collected onto transparent tape. 3D information obtained by serial light and electron microscopy allows identifying regions of interest that are then directly accessible for targeted FIB-SEM. The set of serial semithin sections thus represent a tissue ‘library’, which provides information about microscopic tissue context that can then be probed ‘on demand’ by local high resolution analysis. We demonstrate the potential of this technique to reveal the ultrastructure of rare but pathologically important events by identifying microglia contact sites with amyloid plaques in a mouse model for familial Alzheimer’s disease.

Saltatory Movements of Organelles in Intact Nerves of Rhodnius Prolixus STÅL

1977 ◽  
Vol 70 (1) ◽  
pp. 247-257
Author(s):  
J. P. HESLOP ◽  
E. A. HOWES
Keyword(s):  
Electron Microscopy ◽  
High Power ◽  
Light Microscope ◽  
Light And Electron Microscopy ◽  
Time Lapse ◽  
Rhodnius Prolixus ◽  
Axonal Flow ◽  
Different Temperatures ◽  
Intracellular Organelles

1. Abdominal nerves of Rhodnius prolixus were studied with the light microscope under high-power Nomarski optics with a minimum of surgical interference. The preparation was perfused with bathing solutions which could be changed during time-lapse cinematography. 2. The structure of the nerve trunks was studied by light and electron microscopy. 3. The movements of intracellular organelles are described and discussed. 4. Saltatory movements of organelles, probably mitochondria, were followed at different temperatures. Rate of saltation varied linearly with temperature. 5. Axonal flow (bulk movement of cytoplasm) did not occur in healthy abdominal nerves.

scholarly journals Annexin 11 is required for midbody formation and completion of the terminal phase of cytokinesis

2004 ◽  
Vol 165 (6) ◽  
pp. 813-822 ◽  
Author(s):  
Alejandra Tomas ◽  
Clare Futter ◽  
Stephen E. Moss
Keyword(s):  
Cell Cycle Progression ◽  
Time Lapse ◽  
Terminal Phase ◽  
Aurora B ◽  
Cycle Progression ◽  
Daughter Cells ◽  
Time Lapse Microscopy ◽  
Spindle Poles ◽  
Spindle Midzone ◽  
Late Telophase

Annexins are Ca2+-binding, membrane-fusogenic proteins with diverse but poorly understood functions. Here, we show that during cell cycle progression annexin 11 translocates from the nucleus to the spindle poles in metaphase and to the spindle midzone in anaphase. Annexin 11 is recruited to the midbody in late telophase, where it forms part of the detergent-resistant matrix that also contains CHO1. To investigate the significance of these observations, we used RNA interference to deplete cells of annexin 11. A combination of confocal and video time-lapse microscopy revealed that cells lacking annexin 11 fail to establish a functional midbody. Instead, daughter cells remain connected by intercellular bridges that contain bundled microtubules and cytoplasmic organelles but exclude normal midbody components such as MKLP1 and Aurora B. Annexin 11–depleted cells failed to complete cytokinesis and died by apoptosis. These findings demonstrate an essential role for annexin 11 in the terminal phase of cytokinesis.

Budding patterns during the cell cycle of the maize smut pathogen Ustilago maydis

1994 ◽  
Vol 72 (11) ◽  
pp. 1675-1680 ◽  
Author(s):  
Charles W. Jacobs ◽  
Stephen J. Mattichak ◽  
James F. Knowles
Keyword(s):  
Electron Microscopy ◽  
Cell Cycle ◽  
Mother Cell ◽  
Light And Electron Microscopy ◽  
Ustilago Maydis ◽  
Time Lapse ◽  
Serial Passage ◽  
Cellular Polarity ◽  
Regulatory Pathways ◽  
Bud Site

Haploid sporidia of the dimorphic phytopathogen Ustilago maydis (D.C.) Corda reproduce by budding once each cell cycle. Homogeneous log-phase sporidial cultures were generated by serial passage in liquid culture, and the growth characteristics and percentages of budded cells were determined for the cultures. The characteristics of budding were determined for individual cells by light and electron microscopy. Buds emerged only from the poles of mother cells, and cells could select either a previously used bud site, or a new bud site, each cycle. Time-lapse photomicroscopy indicated that, on solid medium, the first two buds emerged from new cells at a point distal to the site of attachment to the mother cell. In subsequent cell cycles, the buds tended to emerge from alternate poles of the mother cell. The cells used multiple bud sites at each pole. In addition, transmission and scanning electron microscopy revealed a series of annulations (bud scars) at the base of some buds, indicating that cells also used the same budding site many times. This versatility in selecting bud sites indicates that budding likely depends on complex regulatory pathways for determining cellular polarity. Key words: Ustilago maydis, bud, polarity, cell cycle, morphogenesis, yeast.

The Morphology of Vacuolated Cells in the Liver Following Administration of Vitamin A.

1973 ◽  
Vol 31 ◽  
pp. 408-409
Author(s):  
Odell T. Minick ◽  
Hidejiro Yokoo ◽  
Fawzia Batti
Keyword(s):  
Electron Microscopy ◽  
Body Weight ◽  
Vitamin A ◽  
Light And Electron Microscopy ◽  
Liver Cells ◽  
Prominent Feature ◽  
Vascular Space ◽  
Vacuolated Cell ◽  
Vacuolated Cells ◽  
Vacuolated Cytoplasm

Vacuolated cells in the liver of young rats were studied by light and electron microscopy following the administration of vitamin A (200 units per gram of body weight). Their characteristics were compared with similar cells found in untreated animals.In rats given vitamin A, cells with vacuolated cytoplasm were a prominent feature. These cells were found mostly in a perisinusoidal location, although some appeared to be in between liver cells (Fig. 1). Electron microscopy confirmed their location in Disse's space adjacent to the sinusoid and in recesses between liver cells. Some appeared to be bordering the lumen of the sinusoid, but careful observation usually revealed a tenuous endothelial process separating the vacuolated cell from the vascular space. In appropriate sections, fenestrations in the thin endothelial processes were noted (Fig. 2, arrow).

Control of Autogenous Vein Grafts Prior to Reimplantation, By Electron Microscopy

1972 ◽  
Vol 30 ◽  
pp. 106-107
Author(s):  
John H. L. Watson ◽  
John L. Swedo ◽  
M. Vrandecic
Keyword(s):  
Electron Microscopy ◽  
Light And Electron Microscopy ◽  
Physiological Saline ◽  
Experimental Conditions ◽  
Vein Grafts ◽  
Arterial Blood ◽  
Saphenous Veins ◽  
Autogenous Vein ◽  
Control Of Parameters ◽  
Post Implantation

The ambient temperature and the nature of the storage fluids may well have significant effects upon the post-implantation behavior of venus autografts. A first step in the investigation of such effects is reported here. Experimental conditions have been set which approximate actual operating room procedures. Saphenous veins from dogs have been used as models in the experiments. After removal from the dogs the veins were kept for two hours under four different experimental conditions, viz at either 4°C or 23°C in either physiological saline or whole canine arterial blood. At the end of the two hours they were prepared for light and electron microscopy. Since no obvious changes or damage could be seen in the veins by light microscopy, even with the advantage of tissue specific stains, it was essential that the control of parameters for successful grafts be set by electron microscopy.

Ultrastructure of two neoplasms in culture compared with original biopsies

1984 ◽  
Vol 42 ◽  
pp. 50-51
Author(s):  
Joseph M. Harb ◽  
James T. Casper ◽  
Vlcki Piaskowski
Keyword(s):  
Electron Microscopy ◽  
Tissue Culture ◽  
Biopsy Specimen ◽  
Cultured Cells ◽  
Light And Electron Microscopy ◽  
Human Tumor ◽  
Soft Agar ◽  
Human Tumor Cells ◽  
Morphological Distinction ◽  
Tumor Types

The application of tissue culture and the newer methodologies of direct cloning and colony formation of human tumor cells in soft agar hold promise as valuable modalities for a variety of diagnostic studies, which include morphological distinction between tumor types by electron microscopy (EM). We present here two cases in which cells in culture expressed distinct morphological features not apparent in the original biopsy specimen. Evaluation of the original biopsies by light and electron microscopy indicated both neoplasms to be undifferentiated sarcomas. Colonies of cells propagated in soft agar displayed features of rhabdomyoblasts in one case, and cultured cells of the second biopsy expressed features of Ewing's sarcoma.

The Effect of Vitamin A on the Intermittent Nitrogen Dioxide Gas Exposure in Hamsters

1976 ◽  
Vol 34 ◽  
pp. 176-177
Author(s):  
J.C.S. Kim ◽  
M.G. Jourden ◽  
E.S. Carlisle
Keyword(s):  
Electron Microscopy ◽  
Vitamin A ◽  
Nitrogen Dioxide ◽  
Chronic Exposure ◽  
Light And Electron Microscopy ◽  
Specific Effect ◽  
Deficient Diet ◽  
Intermittent Exposure ◽  
Hypovitaminosis A ◽  
Gas Exposure

Chronic exposure to nitrogen dioxide in rodents has shown that injury reaches a maximum after 24 hours, and a reparative adaptive phase follows (1). Damage occurring in the terminal bronchioles and proximal portions of the alveolar ducts in rats has been extensively studied by both light and electron microscopy (1).The present study was undertaken to compare the response of lung tissue to intermittent exposure to 10 ppm of nitrogen dioxide gas for 4 hours per week, while the hamsters were on a vitamin A deficient diet. Ultrastructural observations made from lung tissues obtained from non-gas exposed, hypovitaminosis A animals and gas exposed animals fed a regular commercially prepared diet have been compared to elucidate the specific effect of vitamin A on nitrogen dioxide gas exposure. The interaction occurring between vitamin A and nitrogen dioxide gas has not previously been investigated.

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