Examining pattern formation in mouse, chicken and frog embryos with an En-specific antiserum

Development ◽  
1991 ◽  
Vol 111 (2) ◽  
pp. 287-298 ◽  
Author(s):  
C.A. Davis ◽  
D.P. Holmyard ◽  
K.J. Millen ◽  
A.L. Joyner
Keyword(s):  
Electron Microscopy ◽  
Pattern Formation ◽  
Experimental Studies ◽  
Neural Plate ◽  
Limb Bud ◽  
Good Marker ◽  
Early Embryos ◽  
Whole Mount ◽  
Anterior Neural Plate ◽  
Scanning Electron

We have raised an antiserum, designated alpha Enhb-1, to a portion of the mouse En-2 protein containing the homeodomain. The antiserum detects both the En-1 and En-2 proteins in mouse, chick and Xenopus embryos by Western blot analysis. Using whole-mount immunohistochemistry, combined in some cases with scanning electron microscopy, we have examined the distribution of the proteins in the early embryos of these species. The major features of expression were similar. The initial production of En protein occurred, just before or during the formation of the first somites, in a band of the anterior neural plate in the prospective mid/hindbrain region. Later in development En-1 protein accumulated in the ventral ectoderm of the developing mouse and chick limb buds, indicating that a dorsal-ventral polarity is present as soon as any limb bud swelling is apparent and that, at least in the mouse, this polarity is established independently of the apical ectodermal ridge. In all three species, alpha Enhb-1 bound to a subset of ventro-lateral differentiating neurons in the spinal cord and hindbrain and their pattern of birth in the mouse reflected the division of the hindbrain into rhombomeres. En-1 protein also accumulated in a lateral stripe of dermatome in the mouse and chick, indicating a dorsal-ventral subdivision of this tissue. The results show that En expression is a good marker for pattern formation in a variety of tissues and will be useful in experimental studies designed to characterize further these processes.

Sutureless nonocclusive bypass surgery in combination with an expanded polytetrafluoroethylene graft

2007 ◽  
Vol 107 (6) ◽  
pp. 1190-1197 ◽  
Author(s):  
Jochem P. Bremmer ◽  
Bon H. Verweij ◽  
Albert van der Zwan ◽  
Michael M. Reinert ◽  
Hendricus J. Mansvelt Beck ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Bypass Surgery ◽  
Experimental Studies ◽  
Cerebral Aneurysms ◽  
Ease Of Use ◽  
Repair Tissue ◽  
Eptfe Graft ◽  
Expanded Polytetrafluoroethylene ◽  
Scanning Electron

Object Cerebral aneurysms that cannot be treated by clip or coil placement can be treated with high-flow bypass surgery using techniques such as the excimer laser–assisted nonocclusive anastomosis (ELANA). To simplify the technique, a sutureless ELANA (SELANA) was developed in combination with an expanded polytetrafluoroethylene (ePTFE) graft. Methods In 18 rabbits a bypass was constructed on the abdominal aorta using the SELANA technique with an ePTFE graft, resulting in 18 bypasses and 36 anastomoses. Short-term effects were analyzed in the first 2 weeks and at 2 and 3 months after the procedure. Patency was evaluated using quantitative ultrasound flowmetry. The anastomotic sites were studied using scanning electron microscopy. Results Construction of the bypass using the SELANA technique was easier and faster (15–25 minutes) compared with bypasses made with the ELANA technique (> 90 minutes). At the end of follow-up, 16 of 18 bypasses were patent. Of 36 SELANA anastomoses, 32 could be completed without short temporary occlusion of the recipient vessel. Scanning electron microscopy showed complete coverage of all anastomoses with neointimal repair tissue after 10 days. Conclusions The SELANA technique provides further advantages over the conventional ELANA technique in ease of use and shortening of procedure time. The patency rate in this series was 89% and neointima repair tissue at the anastomosis site was complete after 10 days. Further experimental studies of the long-term patency and safety of this technique are necessary before clinical application.

Investigation on Properties of Magnesia Grinding Wheels Used in Silicon Wafer Grinding

2014 ◽  
Vol 1017 ◽  
pp. 273-278
Author(s):  
Bing Jun Hao ◽  
Zhi Gang Dong ◽  
Shang Gao ◽  
Ren Ke Kang ◽  
Dong Ming Guo
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
Integrated Assessment ◽  
Experimental Studies ◽  
Molar Ratio ◽  
Rockwell Hardness ◽  
Grinding Wheels ◽  
Curing Conditions ◽  
Molar Ratios ◽  
Scanning Electron

This paper presents the results of an experimental investigation on molar ratios of MgO/ MgCl2 affecting the hardness of magnesia grinding wheels, which is one of the most important properties. Magnesite grinding blocks of different ratios of MgO/MgCl2 were prepared. The surface Rockwell hardness of which was tested under the same curing conditions. By an integrated assessment of the experimental studies of hardness and component, it is recognized that the molar ratios of MgO/MgCl2 can significantly affect the properties of magnesia grinding wheels. With the increase of MgO/MgCl2 molar ratio, hardness of the specimens increases. Scanning electron microscopy (SEM) studies on grinding blocks of different ratios indicated that micro needle shaped crystal structure of phase 5 are mainly responsible for hardness development. Finally the optimal recipe was selected in consideration of the characteristics of the silicon mechanical chemical grinding (MCG), which was verified to be effective by the following grinding experiment.

scholarly journals POLYMINERAL COMPOSITE BINDERS FOR FOAM CONCRETE: FEATURES OF HYDRATION AND HARDENING

2020 ◽  
Vol 17 (1) ◽  
pp. 122-135
Author(s):  
V. V. Voronov ◽  
E. S. Glagolev
Keyword(s):  
Electron Microscopy ◽  
Portland Cement ◽  
Building Materials ◽  
Heat Dissipation ◽  
Experimental Studies ◽  
Foam Concrete ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Mineral Additives ◽  
Scanning Electron

Introduction. The paper devotes to the features of hydration and hardening of polymineral composite binders. The authors carry out the complex research of the phase composition, hydration and structure formation processes of hardened composite binders with active mineral additives by X-ray phase analysis, differential scanning calorimetry and electron microscopy. The study using a Tescan MIRA 3 scanning electron microscope reveals differences in the microstructure of hardened binders and the authors confirm the results by microprobe studies. The authors study the hydration of the composite binder prepared on the basis of Portland cement and mineral components. Moreover, the paper demonstrates the dynamics of the system’s heat dissipation from the moment of mixing with water and hardening up to 24 hours and up to 72 hours by the expressed bond of dQ / dt = f (t) using a differential calorimeter.Methods and materials. The authors carried out experimental studies at Belgorod State Technological University named after V.G. Shukhov, at the Department of Building Materials, Products and Structures, at the High Technology Center and “BelGTASM-Certificate” Test Center. Therefore, the authors used the existing basic research methods, including modern physicochemical methods of analysis: X-ray phase, scanning electron microscopy, etc. The paper determined the main characteristics of raw materials, composite binders and foam concrete using standard methods and regulatory requirements.Results. The authors obtained the results that testified the peculiarities of hydration and hardening processes of polymineral composite binders on the basis of Portland cement and mineral additives: opoka marl and fly ash.Conclusion. The research establishes the hydration and hardening processes of polymineral composite binders. As a result, the authors demonstrate that the opoka marl introduced into the cement leads to the increased hydration in the induction and accelerated periods and also increases the hydration completeness of the main clinker minerals due to the manifestation of the pozzolanic reaction and the active binding of blocking Portlandite, as well as to the higher concentration of accumulated neoplasms, second generation calcium hydrosilicates.Financial transparency: the authors have no financial interest in the presented materials or methods. There is no conflict of interest.

Morphological and experimental studies of the somitomeric organization of the segmental plate in snapping turtle embryos

Development ◽  
1984 ◽  
Vol 84 (1) ◽  
pp. 35-48
Author(s):  
David S. Packard ◽  
Stephen Meier
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Final Stage ◽  
Experimental Studies ◽  
The Other ◽  
Chelydra Serpentina ◽  
Microscopy Imaging ◽  
Snapping Turtle ◽  
Somite Formation ◽  
Scanning Electron

The segmental plate mesoderm of snapping turtle embryos (Chelydra serpentina) was examined with stereoscanning electron microscopy imaging. A metameric pattern was detected along the entire length of the segmental plates. This pattern consisted of a tandem sequence of mesodermal units, called somitomeres. Each somitomere was oval to cubic in shape and the processes of the constituent mesodermal cells tended to be arranged in concentric rings about the centre of the somitomere. Several experiments from a previous study (Packard, 1980b) of snapping turtle segmental plates were repeated, but, instead of culturing the explants and observing the numbers of somites that formed, the explants were fixed immediately for scanning electron microscopy and the number of somitomeres was counted. The segmental plates were found to contain an average of 6·5 ± 0·7 somitomeres, which is almost identical to the average number of somites formed by such segmental plates when cultured (6·6 ± 1·2). Furthermore, the number of somitomeres was identical in right and left explants removed from the same embryo, and the number of somitomeres was consistent regardless of the length of the segmental plate. Both of these observations are identical to those made previously for somite formation in culture. This association between numbers of somitomeres and somites strongly suggests that one gives rise to the other. Finally, it was demonstrated that for each somite formed by a segmental plate in culture, the segmental plate contained one less somitomere. This showed in a direct manner that turtle somitomeres become somites. It was concluded that the segmental plate mesoderm of snapping turtle embryos is already segmented, and that the ‘segmentation’ seen under a dissecting microscope is actually the final stage of somitomere differentiation into an epithelial somite.

scholarly journals Correlated SEM, FIB-SEM, TEM, and NanoSIMS Imaging of Microbes from the Hindgut of a Lower Termite: Methods forIn SituFunctional and Ecological Studies of Uncultivable Microbes

2013 ◽  
Vol 19 (6) ◽  
pp. 1490-1501 ◽  
Author(s):  
Kevin J. Carpenter ◽  
Peter K. Weber ◽  
M. Lee Davisson ◽  
Jennifer Pett-Ridge ◽  
Michael I. Haverty ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Focused Ion Beam ◽  
Isotope Labeling ◽  
Ion Beam ◽  
Imaging Mass Spectrometry ◽  
Experimental Studies ◽  
Bacterial Symbionts ◽  
Ecological Roles ◽  
Scanning Electron

AbstractThe hindguts of lower termites harbor highly diverse, endemic communities of symbiotic protists, bacteria, and archaea essential to the termite's ability to digest wood. Despite over a century of experimental studies, ecological roles of many of these microbes are unknown, partly because almost none can be cultivated. Many of the protists associate with bacterial symbionts, but hypotheses for their respective roles in nutrient exchange are based on genomes of only two such bacteria. To show how the ecological roles of protists and nutrient transfer with symbiotic bacteria can be elucidated by direct imaging, we combined stable isotope labeling (13C-cellulose) of live termites with analysis of fixed hindgut microbes using correlated scanning electron microscopy, focused ion beam-scanning electron microscopy (FIB-SEM), transmission electron microscopy, and high resolution imaging mass spectrometry (NanoSIMS). We developed methods to prepare whole labeled cells on solid substrates, whole labeled cells milled with a FIB-SEM instrument to reveal cell interiors, and ultramicrotome sections of labeled cells for NanoSIMS imaging of13C enrichment in protists and associated bacteria. Our results show these methods have the potential to provide direct evidence for nutrient flow and suggest the oxymonad protistOxymonas dimorphaphagocytoses and enzymatically degrades ingested wood fragments, and may transfer carbon derived from this to its surface bacterial symbionts.

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