CLEARING Flashcards

1
Q

PURPOSE OF CLEARING

A
  1. Removing dehydrant from tissue, and replacing it with a fluid miscible to both dehydrant and embedding agent.
  2. Makes tissues “translucent” or transparent, hence the term clearing.
  3. Most are flammable fluids and have low boiling points
  4. Excessive clearing may cause brittleness
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2
Q

CHARACTERISTICS OF GOOD CLEARING AGENT

A

• It should be miscible with alcohol.
• It should be miscible with paraffin wax.
• It should not produce tissue shrinkage.
• It should make tissue transparent.
• It should not dissolve aniline dyes.
• It should not evaporate quickly in water bath

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3
Q

Alcohol clearing agents

A

Xylene
Toluene
Benzene

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4
Q

Time to complete CLEARING

XYLENE

A

30mins to 1hr

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5
Q

Time to complete CLEARING

TOLUENE

A

1-2hrs

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6
Q

Time to complete CLEARING

TOLUENE

A

1-2hr

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7
Q

Time to complete CLEARING

BENZENE

A

15mins-1hr

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8
Q

• rapid, suitable for urgent biopsies
• Makes the tse transparent
• Miscible both in alcohol and paraffin
• Cheap

A

XYLENE

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9
Q

・ Miscible both in alcohol and paraffin
・Does not make tse hard and brittle
・Not carcinogenic

A

TOLUENE

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10
Q

• For URGENT biopsies
• Fastest clearing agent

A

BENZENE

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11
Q

Highly flammable

> 3 hours, makes tse hard

Not suitable for nervous tissues and lymph nodes

A

XYLENE`

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12
Q

Slower than xylene

More expensive

A

TOLUENE

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13
Q

Carcinogenic

May lead to aplastic anemia

A

BENZENE

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14
Q

Time to complete CLEARING

CHLOROFORM

A

6-24hrs

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15
Q

Time to complete CLEARING

CEDARWOOD OIL

A

2-3days

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16
Q

• Tough tissues and large specimens
Skin, fibroid and decalcified tissues (requires longer processing time)

• Toxic to liver (prolong inhalation)

A

CHLOROFORM (6-24 hours)

17
Q

• For smooth muscle, CNS (requires deeper penetration)
• Milky on prolonged storage

A

CEDARWOOD OIL (2-3 days)

18
Q

• For insects, embryos, and delicate tissues

A

ANILINE OIL

19
Q

• Minimum shrinkage of tissues
• Slow, expensive and difficult to use (not usually used in the laboratory)

A

CLOVE OIL

20
Q

• Tough tissues and large specimens (same tse of choice to chloroform)
• Skin, fibroid and decalcified tissues
• Similar to chloroform but cheaper
• Dangerous to inhale on prolonged exposure

A

CARBON TETRACHLORIDE

21
Q

Nontoxic but with offensive odor and should be used in a well-ventilated room
This considered superior among other agents since it can process both DEHYDRATION AND CLEARING thus shorter processing time

A

TETRAHYDROFURAN

22
Q

Causes greater shrinkage than xylene
Dangerous, toxic to liver

A

DIOXANE

23
Q

Used when clearing directly from water (as in a frozen section)

A

GUM SYRUP & GLYCERIN

24
Q

For skin and smooth muscle

A

OIL OF BERGAMOT

25
Q

For skin

A

OIL OF OREGANUM

26
Q

L oil for delicate tissues

A

OIL OF WINTERGREEN

27
Q

For smooth muscle

Has foul odor

A

CARBON DISULFIDE

28
Q

For friable tissue

A

CARBOL XYLENE

29
Q

For delicate tissues like eyes

A

TERPINEOL

30
Q

For smooth muscles

A

PHENOL

31
Q

Excellent clearing agent

A

LEAD-FREE GASOLINE

32
Q

Bbb

A