Answer: Both require a vacuum.
The common feature of scanning electron microscope and transmission electron microscope is that they both require vacuum.
Explanation:
Electron microscope has various advantages over light microscope due to their better magnification and resolution. The transmission electron microscope and scanning electron microscope use electrons for functioning. Thus they require vacuum for their operation since the electrons will be lost in the absence of vacuum.
Thus it is impossible to examine living cells under an electron microscope. The nature of the images formed by these microscopes is different. Transmission electron microscopes produce 2 D images while scanning electron microscopes produce 3D images.
