Microscopy Flashcards
(25 cards)
what is a light field microscope?
most common, observes stained sections, cells must be fixed
what is a phase contrast microscopy?
observes living cells, black and white image, amplifies the difference in RI
what cells is phase contrast microscopy good for?
live and unstained cells
what is differential interference contrast microscopy?
similar to phase contrast but greater resolution of 3D appearance
what is dark field microscopy?
illuminates cells and tissues against a dark background to allow contrast
what is fluorescent microscopy?
uses fluorescent molecules to observe structures
what is confocal microscopy?
uses lasers and optical modifications to focus on a single plane
what pieces of tissue are good for staining?
thin sections that are transparent to light
what is a vital dye?
can penetrate cells and assess culture viability
what is dye exclusion?
dye that cannot penetrate viable cells, such as trypan blue
what is dye uptake?
dye taken up by a living cell such as methylene blue
what does haematoxylin do?
stains nuclei black and cytoplasm pink
how does enzyme histochemistry work?
tissue incubated with substrates and when the enzymes react, a coloured product is produced
what is autoradiography?
makes use of radioactive emissions blackening a photographic plate
what is an example of autoradiography?
precursor substances such as H or C injected in vivo, when in contact with photographic plate, the radioactive isotope causes the silver grains to blacken
what is interference microscopy?
one beam through the specimen and one not, light through the specimen has a phase change, causing a difference in refractive index giving fringe pattern
what is a use of interference?
can be used for quantitative measures such as dry weight
what is a polarising microscope?
specimen placed between crossed polaroids and some areas where polarisation is rotated by the birefringence of the specimen, it is brighter than the background
what is birefringence?
property of a material where the RF of a material depends on the polarisation of light
what is UV microscopy?
certain substances strongly absorb UV light so detected if illuminated by UV light
what is direct immunofluorescence?
specific antibodies to the antigen are injected which are labelled with fluorescent dye
what is indirect immunofluorescence?
primary antibody injected and allowed to bind and secondary labelled antibody that is complementary is injected
what may cause artefacts to be formed?
swelling or shrinking due to tissue fixation, inadequate staining, enzyme action, incomplete dehydration
what is the resolution equation?
D = 0.61 x wavelength/rf of air x sin x alpha
