High-pressure freezing is a powerful tool for visualization of Schizosaccharomyces pombe cells: ultra-low temperature and low-voltage scanning electron microscopy and immunoelectron microscopy

2006 ◽  
Vol 55 (2) ◽  
pp. 75-88 ◽  
Author(s):  
M. Osumi
1997 ◽  
Vol 3 (3) ◽  
pp. 193-202 ◽  
Author(s):  
Mark W. Tengowski ◽  
Gerald Schatten

Abstract: To optimize specimen-processing protocols for investigations of fertilization in mammals, with high-resolution, low-voltage scanning electron microscopy (LVSEM), bovine oocytes matured in vitro were prepared by either aldehyde fixation, conductive staining, or high-pressure cryoimmobilization with freeze-substitution. Samples prepared by these different preparative techniques were coated with either platinum or gold and imaged with an LVSEM operating at 1.5 keV. Additionally, aldehyde-fixed oocytes, sputter-coated with gold, were imaged with a conventional scanning electron microscope (cSEM). The results show that bovine oocytes prepared by aldehyde fixation or cryoimmobilized by high-pressure freezing produced superior images of the zona pellucida (ZP) compared with those from the conductive stained samples. A comparison of LVSEM and cSEM images suggests that the gold-coating employed in cSEM preparation obscures the ZP detail seen with the LVSEM, but not with the cSEM. Application of these procedures provide not only a new view of the ZP but may be useful in elucidating the molecular mechanism of gamete interactions during the fertilization process.


Author(s):  
Marek Malecki ◽  
James Pawley ◽  
Hans Ris

The ultrastructure of cells suspended in physiological fluids or cell culture media can only be studied if the living processes are stopped while the cells remain in suspension. Attachment of living cells to carrier surfaces to facilitate further processing for electron microscopy produces a rapid reorganization of cell structure eradicating most traces of the structures present when the cells were in suspension. The structure of cells in suspension can be immobilized by either chemical fixation or, much faster, by rapid freezing (cryo-immobilization). The fixation speed is particularly important in studies of cell surface reorganization over time. High pressure freezing provides conditions where specimens up to 500μm thick can be frozen in milliseconds without ice crystal damage. This volume is sufficient for cells to remain in suspension until frozen. However, special procedures are needed to assure that the unattached cells are not lost during subsequent processing for LVSEM or HVEM using freeze-substitution or freeze drying. We recently developed such a procedure.


Author(s):  
Arthur V. Jones

In comparison with the developers of other forms of instrumentation, scanning electron microscope manufacturers are among the most conservative of people. New concepts usually must wait many years before being exploited commercially. The field emission gun, developed by Albert Crewe and his coworkers in 1968 is only now becoming widely available in commercial instruments, while the innovative lens designs of Mulvey are still waiting to be commercially exploited. The associated electronics is still in general based on operating procedures which have changed little since the original microscopes of Oatley and his co-workers.The current interest in low-voltage scanning electron microscopy will, if sub-nanometer resolution is to be obtained in a useable instrument, lead to fundamental changes in the design of the electron optics. Perhaps this is an opportune time to consider other fundamental changes in scanning electron microscopy instrumentation.


2002 ◽  
Vol 10 (2) ◽  
pp. 22-23 ◽  
Author(s):  
David C Joy ◽  
Dale E Newbury

Low Voltage Scanning Electron Microscopy (LVSEM), defined as operation in the energy range below 5 keV, has become perhaps the most important single operational mode of the SEM. This is because the LVSEM offers advantages in the imaging of surfaces, in the observation of poorly conducting and insulating materials, and for high spatial resolution X-ray microanalysis. These benefits all occur because a reduction in the energy Eo of the incident beam leads to a rapid fall in the range R of the electrons since R ∼k.E01.66. The reduction in the penetration of the beam has important consequences.


Micron ◽  
1996 ◽  
Vol 27 (3-4) ◽  
pp. 247-263 ◽  
Author(s):  
David C. Joy ◽  
Carolyn S. Joy

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