CLEARING

Question 1

• serves as a bridge between dehydration and infiltration

Answer 1

Clearing

Question 2

Clearing
• serves as a bridge between _____ and _____

Answer 2

dehydration and infiltration

Question 3

______ and ______ are immiscible

Answer 3

paraffin wax and ethanol

Question 4

______ are miscible with both ethanol and paraffin wax

Answer 4

clearing agents

Question 5

Clearing agent

Answer 5

Xylene

Question 6

Clearing

many (but not all) clearing agents impart an _____ or _____to the tissue
- high refractive index

Answer 6

optical clarity or transparency

Question 7

Clearing
• remove substantial amount of____ from tissue

Answer 7

fat

Question 8

_____presents a barrier to wax infiltration

Answer 8

fat

Question 9

Clearing
• performed in both:

Answer 9

• embedding process
• mounting tissues

Question 10

Clearing in

• embedding process

Answer 10

Bridge between dehydration and infiltration

Question 11

Clearing in - mounting tissues

Answer 11

After staining

To make slide clearer

Question 12

Choice of
Clearing Agent
• depends on:

Answer 12

• the type of tissue
• type of processing and processor system
• intended processing conditions
  • e.g. temperature, vacuum and pressure
• safety factors, cost and convenience

Question 13

Examples of Clearing Agents

Answer 13

Organic Solvents

Oils

Question 14

Clearing agents

Answer 14

• Xylene
• Benzene
• Toluene
• Terpineol
• Chloroform
• others

Question 15

Oils

Answer 15

• Cedarwood oil
• Aniline oil
• Clove oil
• Oil of Bergamot
• Oil of oreganum
• lead-free gasolie

Question 16

Xylene (3) characteristics

Answer 16

• most common
• rapid
• readily miscible with paraffin wax

Question 17

tissues best cleared from absolute alcohol

Why?

Answer 17

• incomplete dehydration will cause xylene to turn milky

Question 18

• used for both embedding and mounting procedures

Answer 18

Xylene

Question 19

Xylene

prolonged treatment is avoided
- can cause…

Answer 19

hardening of tissues

Question 20

Xylene

• not preferred for ___ or ____

Answer 20

brain or CNS tissues

Question 21

Procedure
• Xylene 1
• Xylene 2
• Xylene 3

• Place on paper towels to dry.
• Wrap in foil.

Answer 21

20 min
20 min
45 min

Question 22

Actual lab procedure

X1
X2

Answer 22

30mins
45mins

Question 23

Initial deparaffinization

Answer 23

Microwave oven

Question 24

Xylene

Sa H&E staining, ang first 3 stages didto kay…for

Answer 24

Final paraffinization

Question 25

After staining Last 3 xylene station is for…

Answer 25

Clearing before mag mount

Question 26

Aside from clearing agent, cylene can be used as an…

Answer 26

Indicator if dehydration is not done properly Milky xylene

Question 27

What to use for brain or CNS tissues

Answer 27

Toluene

Question 28

Why is toluene not routinely used

Answer 28

Expensive

Question 29

Reagent which clears tissue slowly

Answer 29

Toluene

Question 30

In the______ we clear tissues after dehydration to prepare the tissues for its exposure to wax.

Answer 30

embedding process

Question 31

In______, we clear tissue sections after they have been stained to prepare it for microscopic evaluation.

Answer 31

mounting

Question 32

: clears less rapidly than xylene or chloroform, but does not harden tissue – hence, it is preferred for processing brain sections

Answer 32

Toluene

Question 33

Its properties are relatively similar to xylene. It is non-carcinogenic although high concentrations may emit fumes that are toxic upon prolonged exposure. It is also more expensive.

Answer 33

Toluene

Question 34

: more gentle and rapid than xylene and toluene and is probably the best transition solvent, though toxicity and possible carcinogenicity preclude its use in histology.

Answer 34

Benzene

Question 35

: expensive, heavy, highly volatile, slowly penetrating transition solvent. It causes less brittleness than xylene and is often used on dense tissues such as uterus and muscle which can be cleared overnight without undue hardening.

Answer 35

Chloroform

Question 36

Since_____ attacks some plastics and sealants its use may be restricted in certain closed system processors.

Answer 36

chloroform

Question 37

: clear almost colorless mixture of isomers with a faint pleasant odor and very low evaporation rate

Answer 37

Terpineol

Question 38

It clears tissues from 80%-90% alcohol with minimal hardening. It is a particularly useful substitute for cedarwood oil in manual processing and is also used in open-dish microscopic examination of cleared parasitic helminths.

Answer 38

Terpineol

Question 39

Tissues may remain in it indefinitely without harm. However, it is difficult to eliminate from paraffin wax.

Answer 39

Terpineol

Question 40

Other examples for organic solvents are:

Answer 40

dioxane, esters like amyl acetate, methyl benzoate and methyl salicylate; carbol-xylene and carbon tetrachloride.

Question 41

: largely composed of cedrene, rapidly clears tissues from 95% alcohol, hardens tissues the least of all the transition solvents, but is difficult to eliminate from tissues during wax infiltration

Answer 41

Cedarwood oil

Question 42

It is particularly useful for processing dense tissues such as uterus or scirrhous carcinomas, and has a role in forensic histopathology in processing the hardened skin margins of electrical burns and bullet wounds.

Answer 42

Cedarwood oil

Question 43

Purpose of clearing

Answer 43

Bridge between dehydration and infiltration Imparts an optical clarity to tissue Remove substantial amount of fat Final deparaffinization