Methods of Histology

Question 1

Tissues are made of two interacting compoinents, what are they?

Answer 1

cells and extracellular matrix

Question 2

What are the types of microscopes? (6)

Answer 2

1. Conventional bright field microscopy
2. Fluorescence
3. Phase-contrast
4. Differential Interference
5. Confocal
6. Polarizing

Question 3

What does bright field microscopy require?

Answer 3

staining

Question 4

What is the principle of phase-contrast microscopy and what does it allow?

Answer 4

based on the principle that light changes its speed when passing through structures with different refractive indices. Allows observation of LIVING non-stained structures.

Question 5

What is fluorescence microscopy based on?

Answer 5

Based on affinity of fluorescent compounds for specific cell components

Question 6

What are the advantages of light microscopy?

Answer 6

• inexpensive
• provides rapid diagnosis
• allows observation of living specimens
• resolving power of LM is 0.2um

Question 7

What are the disadvantages of light microscopy?

Answer 7

• image is 2d
• resolving power is limited by the wavelength of light
• requires maintenance
• requires expertise for proper diagnosis

Question 8

What are the advantages of dissecting microscopes?

Answer 8

• relatively inexpensive
• practical/versatile
• can provide a 3d image
• can be used in microsurgery and with other types of specimens

Question 9

what are the disadvantages of a dissecting microscope?

Answer 9

• low resolving power

- needs to be maintained

Question 10

What is transmission electron microscopy based on?

Answer 10

the interaction of electrons and tissue components

Question 11

What are the advantages of transmission electron microscopy?

Answer 11

• great resolving power ( 0.16nm - 0.18nm)

- very useful for rapid diagnosis of viruses and other microscopic organisms

Question 12

what are the disadvantages of the transmission electron microscope?

Answer 12

• image is 2d
• image is black and white
• cannot be used in living object
• very expensive

Question 13

What can you see using scanning electron microscopy?

Answer 13

the surface only

Question 14

How must tissues be processed for observation in a transmission electron microscope and light microscope?

Answer 14

• must be well preserved (retain structure and molecular composition)
• be sufficiently thin to allow light transmission (cut in microtome 1-7um thick)
• Have enough contrast to observe details (staining)

Question 15

What is the most common staining method?

Answer 15

the Hematoxylin - eosin stain (H&E)