Ultrastructure Features and Three-Dimensional Transmission Electron Tomography of Dhub Lizard (Uromastyx Aegyptia) Cornea and Its Adaptation to a Desert Environment

2016 ◽  
Vol 22 (4) ◽  
pp. 922-932 ◽  
Author(s):  
Saeed Akhtar ◽  
Mousa Alkhalaf ◽  
Adnan A. Khan ◽  
Turki M. Almubrad
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Desert Environment ◽  
Dimensional Electron ◽  
Transmission Electron ◽  
Ultrathin Sections ◽  
Corneal Structure

AbstractWe report ultrastructural features and transmission electron tomography of the dhub lizard (Uromastyx aegyptia) cornea and its adaptation to hot and dry environments. Six corneas of dhub lizards were fixed in 2.5% glutaraldehyde and processed for electron microscopy and tomography. The ultrathin sections were observed with a JEOL 1400 transmission electron microscope. The cornea of the dhub lizard is very thin (~28–30 µm). The epithelium constitutes ~14% of the cornea, whereas the stroma constitutes 80% of the cornea. The middle stromal lamellae are significantly thicker than anterior and posterior stromal lamellae. Collagen fibril (CF) diameters in the anterior stroma are variable in size (25–75 nm). Proteoglycans (PGs) are very large in the middle and posterior stroma, whereas they are small in the anterior stroma. Three-dimensional electron tomography was carried out to understand the structure and arrangement of the PG and CFs. The presence of large PGs in the posterior and middle stroma might help the animal retain a large amount of water to protect it from dryness. The dhub corneal structure is equipped to adapt to the dry and hot desert environment.

Analysis of electron-specimen interactions of thick biological specimens in Transmission Electron Microscopy at 200 KEV

1993 ◽  
Vol 51 ◽  
pp. 204-205
Author(s):  
Karen F. Han ◽  
Alexander J. Gubbens ◽  
Abraham J. Koster ◽  
Michael B. Braunfeld ◽  
John W. Sedat ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Mass Density ◽  
Three Dimensional ◽  
Chromatic Aberration ◽  
Background Intensity ◽  
Objective Lens ◽  
Dimensional Electron ◽  
Accurate Representation ◽  
Transmission Electron

The primary project of our laboratory is the investigation of chromatin structure by three dimensional electron microscope tomography. The goal is to understand how 30nm fibers fold into higher order chromatin structures. Three dimensional tomography involves the reconstruction of an object by combining multiple projection views of the object at different tilt angles. Due to the electronspecimen interaction and the characteristics of lens aberration in the electron microscope, however, the image is not always an accurate representation of the projected object mass density. In this abstract, we analyze the various types of electron-specimen interaction for thick biological specimens up to 0.7 microns thickness.Electron-specimen interactions include single elastic and inelastic, and multiple elastic and inelastic scattering. Of the imaging electrons, the single elastic and the plasmon electrons give rise to image intensities that can be linearly related to the projected object mass density. Multiply scattered elastic electrons contribute to an increase in background intensity. In addition, due to the chromatic aberration of the TEM’s objective lens, multiply scattered inelastic electrons cause a blurring of the image because of an effective broadening of the focus spread.

Characterization of Precipitates by Three-Dimensional Electron Tomography

2007 ◽  
Vol 561-565 ◽  
pp. 2009-2012 ◽  
Author(s):  
Kenji Kaneko ◽  
Keisuke Sato ◽  
Z. Horita ◽  
Koji Inoke
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Electron Tomography ◽  
Three Dimensional ◽  
Dimensional Electron ◽  
Transmission Electron

Structures and morphologies of Ge precipitates in an Al-Ge alloy were characterized by a combination of transmission electron microscopy and three-dimensional electron tomography. Faceting of the precipitates was clearly seen using transmission electron microscopy and varieties of precipitate morphologies were identified by three-dimensional electron tomography.

Remote On-Line Control of a High-Voltage in situ Transmission Electron Microscope with A Rational User Interface

1996 ◽  
Vol 54 ◽  
pp. 384-385
Author(s):  
M.A. O’Keefe ◽  
J. Taylor ◽  
D. Owen ◽  
B. Crowley ◽  
K.H. Westmacott ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
User Interface ◽  
Transmission Electron Microscope ◽  
High Voltage ◽  
Materials Science ◽  
Transmission Electron ◽  
On Line ◽  
Electron Microscopes

Remote on-line electron microscopy is rapidly becoming more available as improvements continue to be developed in the software and hardware of interfaces and networks. Scanning electron microscopes have been driven remotely across both wide and local area networks. Initial implementations with transmission electron microscopes have targeted unique facilities like an advanced analytical electron microscope, a biological 3-D IVEM and a HVEM capable of in situ materials science applications. As implementations of on-line transmission electron microscopy become more widespread, it is essential that suitable standards be developed and followed. Two such standards have been proposed for a high-level protocol language for on-line access, and we have proposed a rational graphical user interface. The user interface we present here is based on experience gained with a full-function materials science application providing users of the National Center for Electron Microscopy with remote on-line access to a 1.5MeV Kratos EM-1500 in situ high-voltage transmission electron microscope via existing wide area networks. We have developed and implemented, and are continuing to refine, a set of tools, protocols, and interfaces to run the Kratos EM-1500 on-line for collaborative research. Computer tools for capturing and manipulating real-time video signals are integrated into a standardized user interface that may be used for remote access to any transmission electron microscope equipped with a suitable control computer.

scholarly journals Meso-Scale Transmission Electron Microscope Tomography Applied for Wax Distribution in Toner Particles

2013 ◽  
Vol 19 (S5) ◽  
pp. 58-61 ◽  
Author(s):  
Mino Yang ◽  
Jun-Ho Lee ◽  
Hee-Goo Kim ◽  
Euna Kim ◽  
Young-Nam Kwon ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
Three Dimensional ◽  
Chromatic Aberration ◽  
Laser Printer ◽  
Medium Voltage ◽  
Transmission Electron ◽  
Z Contrast ◽  
Contrast Image

AbstractDistribution of wax in laser printer toner was observed using an ultra-high-voltage (UHV) and a medium-voltage transmission electron microscope (TEM). As the radius of the wax spans a hundred to greater than a thousand nanometers, its three-dimensional recognition via TEM requires large depth of focus (DOF) for a volumetric specimen. A tomogram with a series of the captured images would allow the determination of their spatial distribution. In this study, bright-field (BF) images acquired with UHV-TEM at a high tilt angle prevented the construction of the tomogram. Conversely, the Z-contrast images acquired by the medium-voltage TEM produced a successful tomogram. The spatial resolution for both is discussed, illustrating that the image degradation was primarily caused by beam divergence of the Z-contrast image and the combination of DOF and chromatic aberration of the BF image from the UHV-TEM.

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