clearing

Question 1

process by which alcohol or a dehydrating agent is removed from the tissue and replaced with a substance to dissolve wax or mounting medium

Answer 1

Clearing

Question 2

why is alcohol dissolved during the clearing process

Answer 2

paraffin (wax used for tissue impregnation) does not mix with alcohol.

Question 3

T/F The first step of clearing involves replacing water in the tissue with alcohol during dehydration

Answer 3

True

Question 4

most commonly used clearing agent to dissolve alcohol in tissues

Answer 4

Xylene

Question 5

function of a clearing agent used after alcohol dehydration

Answer 5

mixes with alcohol and removes it from the tissue

Question 6

what happens when the clearing agent is used after tissue section staining?

Answer 6

makes the tissue preparation transparent for microscopic examination.

Question 7

when tissue is cleared directly from water, what is the role of the clearing agent?

Answer 7

improves the refractive index of the tissue without dealcoholization

Question 8

Odd One Out: Characteristic of a good clearing agent
A) Miscible with alcohol
B) Dissolves aniline dyes
C) Makes tissues transparent
D) Easily removed by paraffin wax

Answer 8

B) Dissolves aniline dyes – a good clearing agent should not dissolve aniline dyes.

Question 9

Odd One Out: acceptable property of a clearing agent
A) Causes excessive shrinkage
B) Miscible with alcohol
C) Easily removed by paraffin
D) Makes tissues transparent

Answer 9

A) Causes excessive shrinkage – A good clearing agent should not cause excessive shrinkage.

Question 10

T/F: A good clearing agent should evaporate quickly in a water bath.

Answer 10

False – should not evaporate quickly in a water bath.

Question 11

How does the boiling point of a clearing agent affect the process?

Answer 11

Clearing agents with low boiling points are more readily replaced by melted paraffin wax.

Question 12

T/F Clearing agents with high viscosity can slow the penetration of the clearing agent into the tissue.

Answer 12

T

Question 13

effect of prolonged exposure to a clearing agent on the tissue?

Answer 13

cause the tissue to become brittle.

Question 14

Odd One Out: NOT a factor in choosing clearing agent
A) Cost and convenience
B) Processor system used
C) Ability to dissolve paraffin
D) Type of tissue and processing method

Answer 14

C) Ability to dissolve paraffin – The clearing agent should not dissolve paraffin, but it should be easily removed by it.

Question 15

T/F: The ease of removing the clearing agent by molten paraffin wax is a key consideration when selecting a clearing agent.

Answer 15

T

Question 16

commonly used clearing agent in tissue processing

A) Benzene
B) Cedarwood Oil
C) Xylene
D) All of the above

Answer 16

D) All of the above

Question 17

Odd One Out: Which of the following is NOT a commonly used clearing agent?
A) Xylene
B) Carbon tetrachloride
C) Methanol
D) Toluene

Answer 17

C) Methanol – Methanol is a dehydrating agent, not a clearing agent.

Question 18

most commonly used clearing agent, suitable for tissue blocks less than 5 mm in thickness

Answer 18

Xylene (Xylol)

Question 19

T/F: Xylene is used for both embedding and mounting procedures in routine histologic processing.

Answer 19

T

Question 20

typical clearing time for Xylene?

Answer 20

½ to 1 hour

Question 21

Odd One Out: Advantage of Xylene
A) Miscible with alcohol and paraffin
B) Most rapid clearing agent
C) Extracts aniline dyes
D) Evaporates quickly in a paraffin oven

Answer 21

C) Extracts aniline dyes – Xylene does not extract aniline dyes.

Question 22

disadvantage of using Xylene for more than 3 hours

Answer 22

makes tissue excessively hard

Question 23

Odd One Out: Disadvantage of Xylene
A) Highly inflammable
B) Not suitable for nervous tissues
C) Expensive
D) Makes tissue hard if used over 3 hours

Answer 23

C) Expensive – Xylene is cheap.

Question 24

used as a substitute for Xylene and Benzene, and is less likely to make tissues hard and brittle

Answer 24

Toluene

Question 25

clearing time for Toluene

Answer 25

1-2 hours

Question 26

Odd One Out: Advantage of Toluene A) Miscible with alcohol and paraffin B) Does not make tissues excessively hard C) Slow clearing agent D) Acts fairly rapidly for routine purposes

Answer 26

C) Slow clearing agent – Slower than xylene and benzene.

Question 27

T/F Toluene is slower than Xylene and Benzene, and it acidifies in a partially filled vessel.

Answer 27

T

Question 28

Odd One Out: Disadvantages of Toluene A) Emits toxic fumes upon prolonged exposure B) Acidifies in a partially filled vessel C) Makes tissue brittle after 24 hours D) More expensive

Answer 28

C) Makes tissue brittle after 24 hours – does not make tissues brittle after 24 hours.

Question 29

preferred by some in the embedding process because it penetrates and clears tissues rapidly

Answer 29

Benzene

Question 30

clearing agent that volatilizes rapidly in a paraffin oven, does not make tissues hard and brittle, and causes minimum shrinkage

Answer 30

Benzene

Question 31

T/F Benzene is highly inflammable and may cause tissue shrinkage if left in benzene for a long time.

Answer 31

T

Question 32

Odd One Out: Advantage of Benzene A) Rapid acting B) Does not make tissues hard C) Causes minimum shrinkage D) Suitable for thicker tissue blocks

Answer 32

D) Suitable for thicker tissue blocks – Benzene is used for thinner tissue blocks.

Question 33

serious health risk associated with prolonged exposure to Benzene

Answer 33

extremely toxic to humans upon excessive exposure

Question 34

agent that when used for clearing in embedding process, it's slower than xylene and causes less brittleness

Answer 34

Chloroform

Question 34

T/F Chloroform can be used for thicker tissue blocks (up to 1cm)

Answer 34

T

Question 35

clearing agent suitable for large tissue specimens, nervous tissues, and lymph nodes, and is not inflammable?

Answer 35

Chloroform

Question 36

Odd One Out: Disadvantage of Chloroform A) Toxic to the liver B) Tends to float tissues C) Makes tissues transparent D) Wax impregnation is slow after clearing

Answer 36

C) Makes tissues transparent – Chloroform does not make tissues transparent

Question 37

Odd One Out: Disadvantage of Chloroform A) Complete clearing is difficult to evaluate B) Evaporates quickly from a water bath C) Wax impregnation is slow D) Attacks rubber seals in vacuum baths

Answer 37

B) Evaporates quickly from a water bath – Chloroform evaporates slowly from a water bath.

Question 38

typical clearing time for Cedarwood Oil

Answer 38

2-3 days

Question 39

Odd One Out: Disadvantage of Cedarwood Oil A) Becomes milky upon prolonged storage B) Causes extensive tissue shrinkage C) Hard to eliminate from tissues in paraffin bath D) Expensive

Answer 39

B) Causes extensive tissue shrinkage – minimal shrinkage.

Question 40

T/F: Aniline Oil is commonly used in routine clearing for large tissue samples.

Answer 40

F - not used routinely

Question 41

Clearing agent that causes minimal tissue shrinkage but is unsuitable for routine clearing due to its tendency to adulterate and make tissues brittle

Answer 41

Clove Oil

Question 42

Odd One Out: Disadvantage of Clove Oil A) Expensive B) Causes tissues to become brittle C) Removes aniline dyes D) Makes tissues transparent

Answer 42

D) Makes tissues transparent – Clove Oil does not make tissues transparent.

Question 43

clearing agent that has properties similar to chloroform but produces considerable tissue hardening and is highly toxic

Answer 43

Carbon Tetrachloride

Question 44

T/F: Carbon Tetrachloride is associated with health hazards similar to chloroform, including toxicity upon prolonged exposure.

Answer 44

T

Question 45

what is double embedding, and why are Methyl Benzoate/Methyl Salicylate used for it

Answer 45

It uses two embedding media (e.g., celloidin and paraffin) and these agents are ideal because they act slowly.

Question 46

clearing agent that has the ability to perform both dehydration and clearing at the same time and is non-toxic but has an offensive odor

Answer 46

Tetrahydrofuran

Question 47

T/F: Tetrahydrofuran is toxic and should be handled with caution.

Answer 47

False – non-toxic, but has an offensive odor

Question 48

significant health risk associated with Dioxane

Answer 48

toxic to liver

Question 49

Odd One Out: Disadvantage of Dioxane A) Causes greater shrinkage than xylene B) Toxic to the liver C) Fast-acting in embedding D) Slow tissue impregnation

Answer 49

D) Slow tissue impregnation – fast because it allows tissues to be embedded within 4 hours

Question 50

done to xylene containers to prevent it from entering the atmosphere and sublimating

Answer 50

keep it tightly closed (wow ang oa)

Question 52

T/F: Xylene should be stored in a flammable liquid storage cabinet, away from incompatible substances

Answer 52

T

Question 52

T/F: Coconut Oil is commonly used in the histopathological laboratory as a dealcoholization agent without compromising histological quality.

Answer 52

T

Question 53

Odd One Out: NOT a less-toxic substitute for xylene A) Limonene reagents B) Vegetable oils C) Coconut oil D) Alcohol

Answer 53

D) Alcohol – not a substitute for xylene

Question 54

offer the lowest hazard rating among xylene alternatives and preserve fine tissue structure.

Answer 54

ORANGE OIL BASED CLEARING AGENTS

Question 54

isoprene polymers found in essential oils originally derived from plants.

Answer 54

Terpenes

Question 55

Which of the following is NOT a source of terpenes that can be used as a clearing substitute? A) Oil of bergamot B) Cedarwood oil C) Olive Oil D) Oil of sandalwood

Answer 55

C) Olive Oil – not a terpene; panluto yn tanga

Question 56

oil considered as an efficient substitute for xylene due to being nonhazardous and less expensive

Answer 56

Coconut Oil

Question 56

volatile oil found in citrus peels, such as lemons and oranges

Answer 56

Limonene

Question 57

T/F Orange oil can often be used in place of xylene without altering the protocol.

Answer 57

T

Question 57

effective solvents but are considered toxic chemicals that pose serious health risks

Answer 57

Chlorinated Hydrocarbons

Question 58

Odd One Out: Which of the following is NOT an advantage of Coconut Oil? A) Nonhazardous B) Causes significant shrinkage C) Less expensive D) Good for dealcoholization

Answer 58

B) Causes significant shrinkage – Coconut Oil causes less shrinkage of tissue.

Question 58

provides good tissue sections and is non-toxic, nonhazardous, and nonflammable

Answer 58

Bleached Palm Oil

Question 58

T/F: Bleached Palm Oil is not biodegradable.

Answer 58

F - biodegradable.

Question 59

Odd One Out: Characteristic of Bleached Palm Oil A) Easy to handle B) Highly toxic C) Economic D) Readily available

Answer 59

B) Highly toxic – non-toxic.