... the benefits gained by using an electron microscope also bring specific problems that have to be tackled. Electron beams cannot pass through glass because electrons are physical matter. Therefore there cannot be any lenses used to focus the electrons like there are with optical microscopes. Instead the microscope uses electromagnets to focus the image onto a fluorescent screen. Another problem is that the electrons are very easily interrupted and scattered by molecules in the air so their path is distorted. To overcome this there has to be a very high vacuum inside the microscope so that there is the absence of any other particles in the path of the electron beams. Consequently electron microscopes can only be used to look at dead cells. If a vacuum is present then life cannot exist within it and so the microscope cannot look at living cells. Also the tissue needs to be preserved using ...

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