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electron microscopy (EM)
Classification:
- EM techniques can be roughly divided into two main modalities which each require differently designed electron microscopes
- transmission EM
- an electron beam >= width of the field of view penetrates the sample
- electrons transmitted through the sample create a projection image captured by a detector
- samples are 100-300 nm, due to limited penetration depth of the electron beam
- specimen is gradually tilted to generate a series of 2D projection images at different angles
- these projections can be computationally aligned & combined into a tomographic volume
- the tilt angle is restricted to a maximum of ~70 degrees [1]
- scanning EM
- a focused electron beam scans the surface of the sample
- backscattered electrons are collected by a detector situated above the sample
- can be applied to larger specimens & larger fields of view than transmission EM
- whole cells & specific areas in a cell may be analyzed
- cryotomography is used to image the biological content in a near-native state
- allows the direct visualization of macromolecular complexes like ribosomes & polysomes, clathrin coats, ATP synthases, & individual tubulin subunits in microtubules [1]
Clinical significance:
- resolution ~100 higher than light microscopy
- enables visualization of previously invisible virus particles
Specific
abnormal prion protein in brain by electron microscopy
microscopic observation in stool by electron microscopy
microscopic observation in tissue by electron microscopy
platelet dense bodies in blood by electron microscopy
General
microscopy
References
- Wolff G, Barcena M
Multiscale Electron Microscopy for the Study of Viral Replication Organelles.
Viruses. 2021 Jan 28;13(2):197.
PMID: 33525547 PMCID: PMC7912242 Free PMC article
Images
images related to electron microscopy (EM)