1. The purpose of processing is: - ANSWER remove the water from the tissue to prepare
it for paraffin infiltration and embedding
2. The three steps of processing are: - ANSWER dehydration, clearing, infiltration
3. List four of the factors that affect the effectiveness of tissue processing: - ANSWER size
of tissue, temperature, penetrability, agitation
4. Define viscosity as it relates to the size of molecules in a liquid: - ANSWER a low viscos-
ity will penetrate quicker due to molecules being smaller
5. List four advantages of alcohol as a dehydrating fluid: - ANSWER miscible with water,
acts rapidly, most reagents are soluble with it, more cost effective
6. What are two advantages and disadvantages of using acetone as a dehydrating fluid? -
ANSWER Advantages: penetrates rapidly, less expensive
Disadvantages: flammable, shrinks and makes tissue brittle
7. Why was dioxane discontinued as a dehydrating fluid in tissue processing? - ANSWER
highly toxic
8. Two purposes of the clearing step in processing is to: - ANSWER removing alcohol, pre-
paring tissue for infiltration
9. Define universal solvent: - ANSWER acts as dehydrate and clearing agent
1
, 10. Two universal solvents are: - ANSWER THF and butanol
11. Why are universal solvents not recommended for common usage in tissue processing? -
ANSWER are too toxic and harsh on biopsy
12. List three factors that could be used when considering which processing reagents to use:
- ANSWER tissue size and type, toxicity, and cost
13. The purpose of the infiltration step of processing is: - ANSWER penetrate tissue with
support medium to prepare for embedding
14. Define miscible: - ANSWER able to mix or combine
15. Why is it important that clearing agents are miscible with the infiltration medium? - AN-
SWER paraffin won't infiltrate if clearing agent isn't removed
16. The major advantage to using vacuum during infiltration is: - ANSWER helps penetra-
tion and speeds up processing
17. Why are graded alcohols used in the dehydration steps, instead of going directly into ab-
solute alcohol? - ANSWER if too quick, it can damage tissue (shrink and harden)
18. During the 'clearing' processing step, the tissues become more or less
____________________ because the refractive index of the clearant is near that of the tis-
sue. - ANSWER transparent
1. One indicator of the probable speed of removal of the clearing agent from tissue is its: -
ANSWER molecular size
2
it for paraffin infiltration and embedding
2. The three steps of processing are: - ANSWER dehydration, clearing, infiltration
3. List four of the factors that affect the effectiveness of tissue processing: - ANSWER size
of tissue, temperature, penetrability, agitation
4. Define viscosity as it relates to the size of molecules in a liquid: - ANSWER a low viscos-
ity will penetrate quicker due to molecules being smaller
5. List four advantages of alcohol as a dehydrating fluid: - ANSWER miscible with water,
acts rapidly, most reagents are soluble with it, more cost effective
6. What are two advantages and disadvantages of using acetone as a dehydrating fluid? -
ANSWER Advantages: penetrates rapidly, less expensive
Disadvantages: flammable, shrinks and makes tissue brittle
7. Why was dioxane discontinued as a dehydrating fluid in tissue processing? - ANSWER
highly toxic
8. Two purposes of the clearing step in processing is to: - ANSWER removing alcohol, pre-
paring tissue for infiltration
9. Define universal solvent: - ANSWER acts as dehydrate and clearing agent
1
, 10. Two universal solvents are: - ANSWER THF and butanol
11. Why are universal solvents not recommended for common usage in tissue processing? -
ANSWER are too toxic and harsh on biopsy
12. List three factors that could be used when considering which processing reagents to use:
- ANSWER tissue size and type, toxicity, and cost
13. The purpose of the infiltration step of processing is: - ANSWER penetrate tissue with
support medium to prepare for embedding
14. Define miscible: - ANSWER able to mix or combine
15. Why is it important that clearing agents are miscible with the infiltration medium? - AN-
SWER paraffin won't infiltrate if clearing agent isn't removed
16. The major advantage to using vacuum during infiltration is: - ANSWER helps penetra-
tion and speeds up processing
17. Why are graded alcohols used in the dehydration steps, instead of going directly into ab-
solute alcohol? - ANSWER if too quick, it can damage tissue (shrink and harden)
18. During the 'clearing' processing step, the tissues become more or less
____________________ because the refractive index of the clearant is near that of the tis-
sue. - ANSWER transparent
1. One indicator of the probable speed of removal of the clearing agent from tissue is its: -
ANSWER molecular size
2
