Clearing

Question 1

Removal of the dehydrating agent and replacement with a an agent that is miscible with both dehydrating agents and the embedding medium

Answer 1

Clearing (Dealcoholization)

Question 2

Used in routine tissue processing for removing alcohol; most are flammable liquids with low boiling points; prolonged clearing can cause tissue brittleness

Answer 2

Clearing Agents

Question 3

Colorless clearing agent; most commonly used in routine procedures; rapid clearing time (15-30 minutes to 1 hour); suitable for celloidin sections and tissue sections <5 mm thick; not ideal for nervous tissues or lymph nodes; turns milky if tissues are incompletely dehydrated

Answer 3

Xylene (Xylol)

Question 4

Preferred clearing agent for thick tissue sections

Answer 4

Chloroform

Question 5

Preferred clearing agent for thin tissue sections

Answer 5

Xylene

Question 6

Clearing agent substitute for xylene or benzene; tissues don’t become excessively hard and brittle even after 1 day; non-carcinogenic but toxic with prolonged exposure; clearing time: 1-2 hours

Answer 6

Toluene (Toluol)

Question 7

Recommended for urgent biopsies and routine purposes (15-60 minutes); prevents tissue hardening and brittleness; minimal shrinkage; highly toxic and carcinogenic, associated with aplastic anemia

Answer 7

Benzene

Question 8

Slower clearing agent than xylene (6-24 hours); causes less brittleness; ideal for tough tissues, nervous tissues, lymph nodes; tissues don’t become translucent and tend to float; toxic to the liver

Answer 8

Chloroform

Question 9

Recommended for CNS tissues, cytology (smooth muscles, skin); requires 2 changes of agent; no distortion even if left indefinitely; slow clearing (2-3 days); very expensive and tends to become milky with prolonged storage

Answer 9

Cedarwood Oil

Question 10

Not for routine purposes; recommended for delicate specimens like embryos and insects

Answer 10

Aniline Oil

Question 11

Causes minimal shrinkage but becomes adulterated; recommended for skin and smooth muscles; not for routine purposes

Answer 11

Clove Oil

Question 12

Similar to chloroform but cheaper; causes tissue hardening; highly toxic with prolonged exposure

Answer 12

Carbon Tetrachloride

Question 13

Slow-acting agents used for double embedding techniques

Answer 13

Methyl Benzoate and Methyl Salicylate

Question 14

Used for skin and smooth muscle

Answer 14

Oil of Bergamot

Question 15

Used for skin

Answer 15

Oil of Origanum

Question 16

Artificial oil for delicate tissues

Answer 16

Oil of Wintergreen

Question 17

Clearing agent for smooth muscle; foul odor

Answer 17

Carbon Disulfide

Question 18

Clearing agent for friable tissues

Answer 18

Carbol Xylene

Question 19

Clearing agent for delicate materials like eyes

Answer 19

Terpineol

Question 20

Clearing agent for smooth muscles

Answer 20

Phenol

Question 21

Excellent clearing agent, specifically High-Test Aviation Lead-Free Gasoline

Answer 21

Gasoline