Dehydrating and clearing agents

Question 1

For routine dehydration of tissues
Best dehydrating agent - fast acting
Not poisonous
Not expensive

Answer 1

Ethyl Alcohol

Question 2

Toxic dehydrating agent
Primarily employed for blood and tissue films and for smear preparation

Answer 2

Methyl Alcohol

Question 3

This dehydrating agent is utilized in PLANT and ANIMAL microtechnique
Slow dehydrating agent
Producing less shrinkage and hardening than ethyl alcohol
Recommend for tissue which do not require rapid processing

Answer 3

Butyl Alcohol

Question 4

Routine dehydration process

Answer 4

70% alcohol - 6 hours
95% alcohol - 12 hours
100% alcohol - 2 hours
100% alcohol - 1 hour
100% alcohol - 1hour

Question 5

Dehydration of tissue NOT more than 4mm thick

Answer 5

70% Ethanol -15 min
90% ethanol - 15 mins
100% Ethanol - 15 mins
100% ethanol - 15 mins
100% ethanol - 30 mins
100% Ethanol -45 mins

Question 6

A cheap, rapid acting dehydrating agent
Dehydrates in 1/2 to 2 hours
More miscible with epoxy resins than alcohol
20:1 ratio (Fixative)
Clear, Colorless highly flammable and extremely volatile fluid
Rapid in action but penetrates tissues poorly and causes brittleness in tissues that are prolonged dehydrated
Most lipids are removed
Produces considerable tissue shrinkage
NOT RECOMMENDED for routine dehydration purposes

Answer 6

Acetone

Question 7

Excellent dehydrating and CLEARING agent
Produces less tissue shrinkage
Tissues can be left for long periods of time w/o affecting the consistency or staining properties of the specimen
Tissue sections dehydration with this dehydrating agent tends to ribbon POORLY
EXPENSIVE and extremely dangerous (Vapor is toxic)
Formed peroxide may EXPLODE upon air exposure

Answer 7

Dioxane (Diethyl Dioxide)

Question 8

Dehydrates rapidly
The tissue may be transferred from water or normal saline directly to cellosolve and stored in it for months w/o producing hardening or distortion

Caution: Ethylene glycol ether is combustible at 110F to 120F and is toxic

Propylene based glycol ether should be used instead

Answer 8

Cellosive (Ethylene glycol monoethyl ether)

Question 9

Removes water
Produces very little distortion and hardening of tissues
Soluble in alcohol, water, ether, benzene, chloroform acetone, and xylene
Used to dehydrate SECTIONS AND SMEARS

Answer 9

Triethyl Phosphate

Question 10

BOTH DEHYDRATES and CLEARS tissues since it is miscible in water and paraffin
Can be used for demixing, clearing, and dehydration paraffin sections before and after staining
Causes less shrinkage and EASIER cutting of sections with FEWER artefacts
Does NOT dissolve aniline dyes
TOXIC if INGESTED or INHALED
Vapors causes nausea, dizziness, headache, and anesthesia

Answer 10

Tetrahydrofuran

Question 11

Added to each 95T ethanol bats as part of dehydration process
Acts as a softener for hard tissues

Answer 11

4% Phenol

Question 12

Dehydrating agent for Electron microscopy
Accompanied by PROPYLENE OXIDE as a transition fluid
Along with propylene oxide, this solvent have some undesirable propery

Answer 12

Ethanol

Question 13

A good substitute for propylene
Non-carcinogenic, less toxic, and not as flammable as propylene oxide
Excellent dehydrating agent

Answer 13

Acetonitrile

Question 14

Colorless clearing agent that is MOST COMMONLY used ⭐

Most rapid clearing agent, suitable for urgent biopsies

Clearing time is 1/2 hour to 1 hour

Makes tissue transparent

Does not extract aniline dye

Can be used for Celloidin sections because it does NOT dissolve celloidin

NOT suitable for nervous tissue and lymph nodes

CHEAP

Answer 14

Xylene

Question 15

May be used as a SUBSTITUTE OR ALTERNATIVE ONLY for xylene or benzene ⭐

Clearing time is 1 - 2 hours

Acts fairly rapidly and is recommended for routine purpose

Tissues do not become excessively hard and brittle even if left for 24 hours

NOT carcinogenic

SLOWER than xylene and benzene
EXPENSIVE

Answer 15

Toluene

Question 16

Preferred as a clearing agent in the embedding process of tissues because it penetrates and clears tissues rapidly

Clearing time is 15 to 60 minutes

Does not make tissues hard and brittle but it causes MINIMUM SHRINKAGE

Makes tissues transparent

FLAMMABLE

TISSHUE SHRINKAGE may be OBSERVED if left for a long time

Excessive exposure is TOXIC and CARCINOGENIC to human

May damage the bone marrow resulting in APLASTIC ANEMIA ⭐

Answer 16

Benzene

Question 17

Slower in action than xylene but causes less brittleness

Suitable for LARGE TISSUE SPECIMENS. Thicker blocks can be processed

Clearing time 6-24 hours

Recommended for NERVOUS TISSUES, LYMPH NODES, and EMBRYOS ⭐

NOT FLAMMABLE

Relatively toxic to the LIVER after prolonged inhalataion

Wax impregnation after this clearing agent is relatively slow

DOES NOT make tissue transparent

Difficult to REMOVE from paraffin section because it is NOT very volatile

Complete clearing is difficult to evaluate

Answer 17

Chloroform

Question 18

Advantages and Disadvantages are the same with chloroform ⭐

Produces CONSIDERABLE tissue HARDENING and DANGEROUS to inhale on prolonged exposure due to its highly toxic effects

Answer 18

Carbon tetrachloride

Question 19

Used to clear both PARAFFIN and CELLOIDIN sections during embedding process

Recommended for CNS tissues, and Cytological studies
CCC = _____ , CNS, Cytological

Very penetrating agent

Becomes MILKY upon prolonged storage and should be filtered before use ⭐

VERY EXPENSIVE

Extremely slow clearing agent, not for routine purposes

Clearing time is 2-3 days
Celloidin clearing is 5-6 days

Answer 19

Cedarwood oil

Question 20

Not normally utilized as a clearing agent

Recommended for clearing embryos, INSECTS, and VERY DELICATE SPECIMENS due to its ability to clear 70% ALCOHOL without excessive tissue shrinkage and hardening ⭐

Answer 20

Aniline oil

Question 21

Causes MINIMUM shrinkage of tissues

Its quality is not guaranteed due to its tendency to become ADULTERATED ⭐

Wax impregnation after clearing with this clearing agent is SLOW and DIFFICULT

Tissues become BRITTLE, aniline dyes are REMOVED and celloidin is DISSOLVED

EXPENSIVE and UNSUITABLE for routine clearing purposes

Answer 21

Clove oil

Question 22

Slow-acting clearing agents that can be used when DOUBLE EMBEDDING techniques are required ⭐

OIL OF WINTERGREEN

Answer 22

Methyl benzoate and Methyl Salicylate

Question 23

For frozen section

No de-alcoholization is involved in this process

Answer 23

Glycerin and gum syrup