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Analysis of Cells Using Microscopes Light Microscope Upright Cell membrane Cytoplasm Chromatin Nuclear Membrane Nucleolus Tissue & Cell Examination – – – – – – Cell membrane Cytoplasm Nucleus Nuclear membrane Nucleolus Chromatin or Chromosomes Light Microscopes Upright Inverted...
Analysis of Cells Using Microscopes Light Microscope Upright Cell membrane Cytoplasm Chromatin Nuclear Membrane Nucleolus Tissue & Cell Examination – – – – – – Cell membrane Cytoplasm Nucleus Nuclear membrane Nucleolus Chromatin or Chromosomes Light Microscopes Upright Inverted Phase contrast microscope This microscope uses the fact that various structures in the cell have different “refractive indices” to visualize living cells as light and dark parts. It needs special lenses and filters. For the living cells, no staining or tissue processing is required. Electron Microscopes Transmission EM Scanning EM LM TEM SEM Types of EM • Transmission Electron Microscope (TEM) • • • • • 1930s a very thin section of the sample beam of electrons pass through sample detector forms an image on a surface below → ultra-structure • Scanning Electron Microscope (SEM) • • • • • 1950s whole sample electrons do not pass through the sample beam of electrons interact with sample and then bounce off (scattered) → surface imaging EM vs. LM • EM differs from a light microscope: – electrons are used instead of light – “magnets” are used instead of glass lenses –… – .. LM TEM SEM LM TEM Fluorescence microscope This microscope uses UV light. Cells or tissue sections must be stained with fluorescent dye. The dye will be irradiated with the UV and brilliant shiny light will be emitted against black background. UEA ATPase BrdU GS Confocal microscope This microscope uses laser as the source of light. The laser beam can be controlled to penetrate the thick tissue section at different depths and provide successive images for each. Then by a computer program one can reconstruct these images to produce threedimensional (3-D) image of the whole section.
