1 3 development in imaging technology and staining techniques
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1.3 Development in imaging technology and staining techniques. Contrast. When light passes directly through cells in what is called brightfield microscopy, most cells are seen colourless

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1.3 Development in imaging technology and staining techniques

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1 3 development in imaging technology and staining techniques

1.3 Development in imaging technology and staining techniques


Contrast

Contrast

  • When light passes directly through cells in what is called brightfield microscopy, most cells are seen colourless

  • Staining or using colouring agents showed that particular stains attach to particular parts of the cell, improving contrast between internal structures and producing better images

  • Can be as simple as adding methylene blue or iodine

  • Chemical preservatives “fix” the cell and allow for more complex staining procedure

    • This kills the cell so it is not possible to view living tissue


Staining cells quick lab

Staining Cells- Quick Lab

  • Page 254

  • Do this in partners


Resolution

Resolution

  • Is the ability to distinguish between two structures that are very close together

  • An image should have high resolution if it is to show its detail

  • The clarity of images depends on the resolving power of the microscope

    • However light microscopes efficiency is limited because as light focusses onto smaller and smaller diameters, the image becomes blurry


Fluorescence microscopy

Fluorescence Microscopy

  • Read paragraph on page 256

  • https://www.youtube.com/watch?v=sCYX_XQgnSA


Confocal technology

Confocal Technology

  • Read paragraphs on page 257-258


Electron microscope

Electron Microscope

  • Uses beams of electrons instead of a light wave and is able to produce images that provide fine detail

  • The image is formed by the absorption or scattering of electrons because electron-dense materials do not let the electrons pass through


1 3 development in imaging technology and staining techniques

TEM

  • Transmission Electron Microscope depends on a beam of electrons passed through a very thin section of fixed (not alive) and stained tissue embedded in plastic

  • Can magnify up to 1 500 000x

  • A drawback is the difficulty in building up a three dimensional picture of a cell from a very thin section

    • There is great detail, but the area we are looking at is very small


Light vs electron microscopes

Light vs Electron Microscopes

  • Copy down Table C1.1 on page 259

  • https://www.youtube.com/watch?v=WDkLxlQ3hBA


Scanning electron microscope

Scanning Electron Microscope

  • This gives information about the surface features of a specimen.

  • Specimens are fixed and covered with an electron-dense material like gold which reflects electrons

  • 300 000x magnification

  • A form of the SEM has been developed to allow use to use live materials


Electron micrographs

Electron Micrographs

  • Photographs taken by either the SEM of TEM

  • https://www.youtube.com/watch?v=SIOOLXbwWME


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