Introduction to Microscopy Flashcards
In what two ways to light microscopy and electron microscopy differ?
- Optical resolution
- Available magnification
Light microscopy and electron microscopy differ in ______________ _____________ and ____________ ___________.
Optical resolution
Available magnification
What does “resolution” mean in practical terms?
The capacity of an optical system to reveal detail in a specimen
What is the optical resolution of a typical light microscope?
0.2 µm
What’s the optical resolution of an average electron microscope?
1 nm
What is the available magnification of an average light microscope?
1000X
What is the available magnification in an average electron microscope?
100,000X
What are the two types of electron microscopes?
- Transmission
- Scanning
_______________ EM produces three-dimensional images, but these are restricted to the surface of the object with the internal structure concealed from view.
Scanning
__________________ EM is so named be ause the electron beam must pass through the specimen, which has been cut into ultrathin sections, resulting in a two-dimensional image of section planes.
Transmission
Which electron microscopy is more informative? Transmission or scanning?
Transmission
What is the available area with which one can view under a light microscope?
Several cm2
What is the available area with which an electron microscope can provide?
Less than 1 mm2
What are three ways in which electron microscopy is less flexible than light microscopy?
- The available area is generally less than one square mm
- Few staining methods are available, producing only black and white images
- Costly and time-consuming, thus not available to most students
Electron-dense describese the relative ________________ of an image of a transmission EM.
Darkness
Electron-lucent describes the relative _______________ of an image in electron microscopy.
Lightness
One major group of specific methods known as ________________ techniques employes reagents known to react with defined cellular constituents (e.g., lipids, glycogen and DNA), thereby producing selective coloration recognizable by light microscopy.
Histochemical
In a subset known as _______________ histochemistry, the activity of ________________ can similarly be demonstrated by staining for their specific substrates or end products.
Enzyme
Enzymes
_____________________ is immunologically based in which antibodies are raised against specific cellular components (i.e., antigens) and then conjugated with a visual marker appropriate for LM or EM.
Immunohistochemistry
What is a problem common to both light and electron microscopy?
The need to prevent autolytic degeneration and to preserve cellular ultrastructure
_________________ causes cross-linking of macromolecules, which reduces and arrests biological activity, at the same time rendering the cells more amenable to staining.
Fixation
Fixatives such as ______________ and __________________ are used to prevent autolytic degeneration and to preserve cellular ultrastructure.
Formaldehyde
Glutaraldehyde
Most tissues are too thick to be examined directly in the microscope and thus must be _____________ into thin slices. To faciliate cutting of these thin slices, the tissue is usually ______________ in a hard medium like parrafin wax or plastic resin. Fixed tissues generally require _______________ with organic solvents before this step.
Sectioned
Embedded
Dehydrated
What are artefacts?
Distortions in cell and tissue architecture
What types of light microscopy have been developed to monitor living tissue cultures?
Phase contrast
Interference contrast
Confocal microscopy
