Introduction to Microscopy

Question 1

In what two ways to light microscopy and electron microscopy differ?

Answer 1

1. Optical resolution
2. Available magnification

Question 2

Light microscopy and electron microscopy differ in ______________ _____________ and ____________ ___________.

Answer 2

Optical resolution

Available magnification

Question 3

What does “resolution” mean in practical terms?

Answer 3

The capacity of an optical system to reveal detail in a specimen

Question 4

What is the optical resolution of a typical light microscope?

Answer 4

0.2 µm

Question 5

What’s the optical resolution of an average electron microscope?

Answer 5

1 nm

Question 6

What is the available magnification of an average light microscope?

Answer 6

1000X

Question 7

What is the available magnification in an average electron microscope?

Answer 7

100,000X

Question 8

What are the two types of electron microscopes?

Answer 8

1. Transmission
2. Scanning

Question 9

_______________ EM produces three-dimensional images, but these are restricted to the surface of the object with the internal structure concealed from view.

Answer 9

Scanning

Question 10

__________________ 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.

Answer 10

Transmission

Question 11

Which electron microscopy is more informative? Transmission or scanning?

Answer 11

Transmission

Question 12

What is the available area with which one can view under a light microscope?

Answer 12

Several cm²

Question 13

What is the available area with which an electron microscope can provide?

Answer 13

Less than 1 mm²

Question 14

What are three ways in which electron microscopy is less flexible than light microscopy?

Answer 14

1. The available area is generally less than one square mm
2. Few staining methods are available, producing only black and white images
3. Costly and time-consuming, thus not available to most students

Question 15

Electron-dense describese the relative ________________ of an image of a transmission EM.

Answer 15

Darkness

Question 16

Electron-lucent describes the relative _______________ of an image in electron microscopy.

Answer 16

Lightness

Question 17

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.

Answer 17

Histochemical

Question 18

In a subset known as _______________ histochemistry, the activity of ________________ can similarly be demonstrated by staining for their specific substrates or end products.

Answer 18

Enzyme

Enzymes

Question 19

_____________________ 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.

Answer 19

Immunohistochemistry

Question 20

What is a problem common to both light and electron microscopy?

Answer 20

The need to prevent autolytic degeneration and to preserve cellular ultrastructure

Question 21

_________________ causes cross-linking of macromolecules, which reduces and arrests biological activity, at the same time rendering the cells more amenable to staining.

Answer 21

Fixation

Question 22

Fixatives such as ______________ and __________________ are used to prevent autolytic degeneration and to preserve cellular ultrastructure.

Answer 22

Formaldehyde

Glutaraldehyde

Question 23

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.

Answer 23

Sectioned

Embedded

Dehydrated

Question 24

What are artefacts?

Answer 24

Distortions in cell and tissue architecture

Question 25

What types of light microscopy have been developed to monitor living tissue cultures?

Answer 25

Phase contrast

Interference contrast

Confocal microscopy