Electron Microscopy

High throughput SEM and large samples (millimeters and more) imaging are quite limited and usually are not applicable for high resolution imaging. Software solutions for automated acquisition can be used to overcome the challenge. The Quattro S ESEM (Thermo Fisher Scientific) is…

An environmental scanning electron microscope can work at a higher chamber pressure compared to regular SEM being operated at low pressures (10^-5-10^-7 mbar). Wet mode SEM is a special case where water vapor is introduced into the microscope chamber at a pressure as high as 2000…

Characterization and imaging of hydrated samples, and specifically biological samples, under electron microscopes is challenging as these operate under dry high vacuum conditions. Unless an environmental SEM is available, any moist or gas vapor found in the chamber causes severe…

With the exception of the environmental SEM, liquid water cannot be observed in the SEM due to the high vacuum in the microscope’s column. Due to this limitation, most aqueous samples, biological or synthetic, are observed in the SEM only after the application of chemical…

An illustration of the high-pressure freezing-freeze substitution method.

figure by Neta Varsano

Vitrification provides the best-known means for the preservation of aqueous samples in their native state, since the only perturbation that occurs during vitrification is…

Conventional chemical fixation methods require the removal of water, the main constituent of most biological samples, and often result in various artifacts. Solidification of aqueous samples by lowering their kinetic energy, i.e., freezing, is an alternative physical means for…

Many biological insights can be obtained by combining the power of Fluorescence Microscopy with that of Electron Microscopy to study the same sample – this is called Correlative Light and Electron Microscopy (CLEM). In Fluorescence Microscopy, specific biological entities can be…

An illustration of the Tokuyasu method.

Figure by Neta Varsano

In the Tokuyasu procedure, the sample is fixed using a moderate fixative, typically 0.1% GA 4% PFS in Cacodylate buffer, after which the cell pellet is embedded in gelatin, cut into small cubes, and…

Immuno-gold labeling is a technique used for the identification, localization, and distribution of proteins, antigens, and other macromolecules of interest, at an ultrastructural level, with high resolution. It is a very powerful technique for identifying active sites and the…

For ultrastructural analysis of biological specimens such as various tissues, cells (suspension and cell monolayers), bacteria or plants, the biological sample is stabilized by immersion in a mixture of chemicals containing Glutaraldehyde and formaldehyde. Glutaraldehyde reacts…