S1) Investigative Techniques Flashcards
Identify 3 requirements for light microscopy
- Formalin
- Paraffin
- Haematoxylin and Eosin
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What role does formalin have in light microscopy?
Formalin preserves tissue to prevent it from rotting
What role does paraffin have in light microscopy?
Paraffin embeds the tissue in a substance that allows it to be sliced very thinly
What role does H&E have in light microscopy?
Haematoxylin and Eosin stains the tissue so that we can see cell components
Describe the process of producing a frozen section
- The surgical specimen is placed on a metal disc then frozen rapidly to -20°C to -30°C
- The specimen is cut open with a cryostat
- The tissue is then stained with H&E
Identify an advantage and a disadvantage of frozen sections
- Advantage: prepared more rapidly than traditional histology (10 minutes vs 16 hours)
- Disadvantage: technical quality of sections is much lower
Outline the process of fluorescent microscopy
- Specimen has fluorescent molecules (fluorophores) attached
- Fluorophores emit light when they are irradiated by a specific wavelength of light
- Colours observed can be different components of a cell or the different cell types within a tissue
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When is fluorescent microscopy most commonly used?
Used in the differentiation of different cancer cell types
Outline the process of confocal microscopy
Often combined with fluorescent imaging:
- Fluorescent dye molecules are attached to specific parts of a sample
- Only the labelled parts can be seen in the confocal microscope
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Identify and describe 3 advantages of confocal microscopy
- Produces a sharper image (blocks out of focus light)
- Captures 3D images of specimens
- Allows for imaging of live specimens (images taken at time intervals to create a time-lapse video)
Outline the process of autoradiography
A photographic emulsion is used to visualise molecules labelled with a radioactive marker:
- Marker is injected into the live animal/cell culture
- Histological section is coated with the emulsion
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What is an ultrasound?
Ultrasound are sound waves with frequencies which are higher than those audible to humans (>20,000 Hz)
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Describe the process of performing an ultrasound
- Ultrasonic images are sonograms and are made by sending pulses of ultrasound into tissue using a probe
- The sound echoes off the tissue
- Different tissues reflecting varying degrees of sound
- Echoes are recorded and displayed as an image
Describe the use and aim of the ultrasound
- Use: view internal body structures
- Aim: find a source of a disease or to exclude any pathology
Outline the process involved in Transmission Electron Microscopy
- Uses an electron beam generated in a vacuum
- The electron beam passes through the tissue
- Portions that the beam has passed through appear bright
- Portions that have absorbed or scatter electrons appear dark
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