The principal methods to study cell structure and functions are light and electron microscopy:

• a light microscope allows studying not only separate cells but large areas of histological sections to understand their tissue arrangement (general histology) and structural parameters of different body parts (special histology)
• in a light microscope, resolution (minimal distance between two neighboring objects when both of them can be seen) is not high (about 0.2 μm)
• electron microscopy uses electron beams instead light beams to get a higher resolution (scale in nanometers); the method has two main types, which are transmission and scanning electron microscopy
• the transmission electron microscopy approach (TEM) exploits the same concept as light microscopy, though images are formed due to energy difference between electrons when these electrons pass through objects or are absorbed by them
• in scanning electron microscopy (SEM), an electron beam proceeds along the surface of an object thereby scanning it, whereas those electrons that are reflected from the surface are trapped by detectors to form an image on a monitor screen
• 3D-images in SEM are favorable for cell shape study