Which type of microscope used to study of living cell

Key Points

• Microscopes are important laboratory instruments that are used to enlarge the image of an object many-folds.
• This helps us to study biological specimens like cells and cell structures that are too small for the naked eye and are termed as 'microscopic'.
• However, not all types of microscopes can be used for observing all specimens.
• Each microscope requires the specimen to be prepared in a specific way.
• This determines which microscope suits which type of specimen.
• Most of the microscopes require the specimens to be stained, which eventually kills them.
• So in order to view living cells, we need to use unstained specimens.

Important Points

• The microscope used for study of living cells is phase-contrast microscope.
• Phase-contrast microscopy is based on the principle that small changes in the phase can be transformed into changes in brightness of that object.
• This can be observed as difference in image contrast.
• Phase objects refer to unstained specimens that do not absorb light.
• This microscopy technique is suitable for living cells because unstained specimens are used, keeping the cells alive.

Additional Information

• Compound microscope -
  • It is a type of optical microscope that uses two lenses instead of one to have a better resolution image.
  • The lenses are known as ocular lens and objective lens.
  • It generally uses visible light to view the specimens.
• Oil-immersion microscope -
  • It is used to increase the resolution of a light microscope.
  • It uses a transparent oil to immerse the objective lens as well as the specimen.
  • The oil has a high refractive index, allowing increased aperture of the lens.
  • Light tends to bend (refract) whenever it changes a medium.
  • Oil and glass have similar refractive indices and so they function as almost the same medium causing minimum or no refraction.
  • This creates a sharper image of the specimen.
• Electron microscope -
  • It is a type of microscope that uses an electron beam instead of a beam of light as the source of illumination.
  • It can be used to observe both biological as well as non-biological specimens.
  • They have higher magnification and higher resolution than light microscopes.
• Compound and oil-immersion microscopes cannot be used for living cells as they use stained specimens.
• Electron microscopes require the specimens to be kept in vacuum, which kills living cells.