HISTOPATH LAB CLEARING

Question 1

Colorless.
● Most commonly used.
● Used for clearing, both for
embedding and mounting
procedures.
● Generally suitable for routine
histologic processing schedules
of less than 24 hours and when
tissue block is less than 5 mm in
thickness.

Answer 1

XYLENE
XYLOL

Question 2

May be used as substitute for
xylene or benzene for clearing
both during embedding and
mounting processes.

Answer 2

TOLUENE

Question 3

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

Answer 3

BENZENE

Question 4

Most rapid clearing agent.
● Makes tissues transparent.
● Miscible with absolute alcohol
and paraffin.
● Does not extract out aniline
dyes.
● For mounting procedures.
● During embedding and
impregnation (evaporates
quickly in paraffin oven)
● Cheap

Answer 4

XYLENE

Question 5

Acts fairly rapidly–
recommended for routine
purposes.

● Does not make tissues excessively hard and brittle if
left for 24 hours

● Slower than xylene and
benzene.

Answer 5

TOLUENE

Question 6

Rapid acting.
● Volatilizes rapidly in a paraffin
oven.
● Does not make tissues hard and
brittle.
● Causes minimum shrinkage.
● Makes tissues transparent

Answer 6

BENZENE

Question 7

Clearing time: ½
(30mins.)-1 hour

Answer 7

XYLENE

Question 8

Clearing time: 1-2 hours

Answer 8

TOLUENE

Question 9

Shorter clearing time.

Answer 9

BENZENE

Question 10

When used for clearing in
embedding process, slower than
xylene.

● Causes less brittleness.
● Can be used for thicker tissue
blocks (up to 1cm).

● Tissues do not become
translucent.

Answer 10

CHLOROFORM

Question 11

Used to clear both paraffin and
celloidin sections during the
embedding process.

● Especially recommended for CNS tissues and cytological studies.

● Requires two changes in clearing
solution.

Answer 11

CEDARWOOD OIL

Question 12

Not normally utilized as a routine clearing agent.

● Recommended for clearing
embryos, insects, and very
delicate specimens.

Answer 12

ANILINE OIL

Question 13

For routine work.(6-24 hours)
○ Chloroform first
before xylene!

Answer 13

CHLOROFORM

Question 14

Miscible with absolute alcohol.
● Causes minimum shrinkage-
for tough tissues (e.g.skin,
dibroid, decalcified tissues) for
nervous tissues, lymph nodes
and embryos.

● For large tissue specimens.

● Not inflammable.

Answer 14

CHLOROFORM

Question 15

Toxic to the liver after
prolonged inhalation.

Does not make tissues
transparent.

Answer 15

CHLOROFORM

Question 16

Not very volatile in paraffin
oven.

● Vapor may attack rubber seal
used in vacuum impregnating
bath.

● Complete clearing is difficult
to evaluate

Answer 16

CHLOROFORM

Question 17

Tissues tend to float in
chloroform.

● Evaporates quickly from a
water bath.

Answer 17

CHLOROFORM

Question 18

Tissues may be left indefinitely
without causing considerable
damage and distortion

Answer 18

CEDARWOOD OIL

Question 19

Makes tissues transparent.
● Improves cutting of sections.

Answer 19

CEDRAWOOD

Question 20

Very penetrating.
● Miscible with 96% alcohol
which it removes readily.
● Clears celloidin in 5-6 days.
● Causes minimal shrinkage and
hardening.

Answer 20

CEDARWOOD

Question 21

Extremely slow.
● Hard to be eliminated from
tissues in paraffin bath.

Answer 21

CEDARWOOD

Question 22

Quality not always uniform
and good.

Answer 22

CEDRAWOOD

Question 23

becomes milky
upon prolonged storage.

previously
used to clear acetic-alcohol
fixed tissues may produce
crystals.

Very expensive.

Answer 23

CEDRAWOOD

Question 24

Clearing time: 2-3 days

Answer 24

CEDARWOOD

Question 25

Not normally utilized as a routine clearing agent. Recommended for clearing embryos, insects, and very delicate specimens.

Answer 25

ANILINE OIL

Question 26

Causes minimum shrinkage. Quality not guaranteed– tendency to become adulterated. Wax impregnation is slow and difficult.

Answer 26

CLOVE OIL

Question 27

Tissues become brittle, aniline dyes removed, celloidin is dissolved. ● Expensive. Unsuitable for routine clearing purposes.

Answer 27

CLOVE OIL

Question 28

Used in clearing tissues for embedding. ● Properties similar to chloroform. Produces considerable tissue hardening.

Answer 28

CARBON TETRACHLORIDE

Question 29

Highly toxic-dangerous to inhale on prolonged exposure.

Answer 29

CARBON TETRACHLORIDE

Question 30

Slow-acting clearing agents. Can be used when double embedding techniques are required.

Answer 30

METHYL BENZOATE METHYL SALICYLATE

Question 31

Ability to perform two processes at the same time. Non-toxic but has an offensive color.

Answer 31

TETRAHYDROFURAN

Question 32

Tissues may be embedded with paraffin within 4 hours Causes greater shrinkage than xylene does Toxic to human especially to the liver.

Answer 32

DIOXANE

Question 33

Tissues may be embedded with paraffin within 4 hours Causes greater shrinkage than xylene does Toxic to human especially to the liver.

Answer 33

DIOXANE

Question 34

isoprene polymers found in essential oils originally derived from plants,

Answer 34

TERPENES

Question 35

volatile oil found in citrus peels which goes by several trade names. ⟶ It is a natural oil found in the skins of citrus fruits, such as lemons or oranges, and in cooking is usually referred to as lemon or orange zest.

Answer 35

LIMONENE

Question 36

Offer the clearing action with the lowest hazard rating of all xylene alternatives. ⟶ It is excellent for preserving fine tissue structure, and can often be used in place of xylene with no alteration of protocol

Answer 36

ORANGE OIL BASED

Question 37

Can be effective solvents, but they are considered toxic chemicals, posing serious health risks.

Answer 37

CHLORINATED HYDROCARBONS

Question 38

efficient substitute for xylene, as it is non- hazardous, less expensive and causes less shrinkage of the tissue. It can be used as a dealcoholization agent

Answer 38

COCONUT OIL

Question 39

Gives good tissues, sections and histological slides. ⟶ Nontoxic, nonhazardous, nonflammable, biodegradable, economic, easy to handle, and readily available.

Answer 39

BLEACHED PALM OIL

Question 40

not suitable for nervous tissues and lymph nodes

Answer 40

XYLENE

Question 41

Acidifies in a partially filled vessel. ● Highly conc. solutions will emit fumes that are toxic upon prolonged exposure. ● More expensive.

Answer 41

TOLUENE

Question 42

APLASTIC ANEMIA

Answer 42

BENZENE

Question 43

6-24 HOURS

Answer 43

CHLOROFORM

Question 44

MAKES TISSUE EXCESSIVELY HARD IF USED OVER 3 HOURS

Answer 44

XYLENE

Question 45

does not make tissues excessiveley hard and brittle if left for 24 hrs

Answer 45

TOLUENE