GENERAL HISTOLOGY

Detailed explanation-1: -A beam of electrons is produced at the top of the microscope by an electron gun. The electron beam follows a vertical path through the microscope, which is held within a vacuum. The beam travels through electromagnetic fields and lenses, which focus the beam down toward the sample.

Detailed explanation-2: -Most electron microscopes are high-vacuum instruments. Vacuums are needed to prevent electrical discharge in the gun assembly (arcing), and to allow the electrons to travel within the instrument unimpeded.

Detailed explanation-3: -Scanning electron microscope (SEM)

Detailed explanation-4: -Electron microscopes use electrons rather than visible light to create an image. In order to use electrons for microscopy, you must focus the electron beam, and you need a vacuum. The beam is sent onto the sample, bounces off and creates a three-dimensional image of the surface.

Detailed explanation-5: -A vacuum environment means that most of the air molecules have been removed from the inside of the microscope. You can think of vacuum as a density; there are a certain number of gas molecules in a given space.