Imaging Flashcards
List the macro-scale imaging technologies.
Ultrasound, Micro-CT, OPT
What are ultrasounds used for?
Pregnancy imaging
What is the purpose of using computer-aided image enhancement with ultrasounds?
Develop clear images of the foetus
What is optical projection tomography (OPT) used for?
Constructing 3D models of animal model embryos. Can be paired with use of fluorescent antibodies, staining, fluorescence expression.
How does OPT work?
The embryo and its environment is made transparent chemically. Light is passed through.
Thicker areas-darker shadows.
Turn the camera 260 degrees to reconstruct the 3D image of the embryo.
Can OPT be used for large structures?
No, the size of the mouse embryo is the max.
What techniques can OPT be paired with?
Fluorescent antibodies, staining, fluorescence expression.
List the micro-scale imaging techniques.
Light microscopy, confocal microscopy, electron microscopy.
What is 3D morphometric analysis used for?
Measurements of human foetuses to detect abnormalities.
What is resolution?
Ability to distinguish two objects as separate entities.
What is the resolution of a light microscope?
200nm
What is the magnification that can be obtained using a light microscope?
x40 - x100
What is confocal microscopy?
Use of lasers to generate fluorescent images of one slice of a sample.
What colour are the DAPI and the Hoechst stains and what do they stain?
Blue, nucleus.
What is the resolution of an electron microscope?
50pm
Compare EM wavelengths to visible light wavelengths.
100 000x shorter
What are the 8 steps of specimen preparation?
Fixation, embedding, sectioning, mounting, clearing and rehydration, staining, dehydration and clearing, final mounting.
What is the purpose of fixation?
Cross-link proteins and stabilise cellular structure.
What is a common base in fixatives?
Formaldehyde
What is the purpose of embedding?
Provide support for tissue
What can be used for embedding tissue?
Wax (parafin), resin, freezing
What is used for slicing?
Microtome
How thick are slices produced for viewing under a microscope?
5-10 microns
How are clearing and rehydration performed?
Xylene is used for clearing and decreasing levels of alcohol are used for rehydration.
Why are sections dehydrated and cleared after staining?
To improve resolution
What does haematoxylin stain and what colour?
Nucleus, blue
What does eosin stain and what colour?
Cytoplasm, pink
What does alcian blue stain and what colour?
Connective tissue, blue
