007. The aim of the paragraph as a whole is to inform
A)effectiveness of TVM in EV imaging
B)how TVM works
C)usefulness of CDC in TVM
Transmission Electron Microscopy
Transmission electron microscopy (TEM) is the most common type of electron microscopies for EV imaging, such as exosomes, microvesicles, oncosomes and migrasomes. The samples prepared for TEM imaging are first fixed and later dehydrated. Following dehydration, the samples need to be embedded, sliced into nanometered thin sections, and mounted on a carbon coating grid for imaging. TEM uses electron beams to illuminate through prepared specimens, and the electron can either transmit or be diffracted by the specimens. A fluorescent screen or charge-couple device (CCD) will collect the transmitted electron for bright-field images, which is normally used for structure verification. Meanwhile, scattered electrons are collected to generate dark-field images, revealing the structure with a higher contrast. Notably, EVs observed by TEM often appear as cup shaped as a result of dehydration during sample preparation but can effectively reveal inner structure of EVs.
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