HISTOPATHOLOGY CLEARING & IMPREG

Question 1

appearance of tissue after it has been treated by the fluid chosen to remove the dehydrating agent

Answer 1

Clearing

Question 2

IN Clearing, Most of these tissues have similar refractive index to that of protein therefore the tissue is left ___________

Answer 2

translucent

Question 3

Clearing agent is required when the dehydrating agent is not ______ with the ___________ medium.

Answer 3

miscible ; impregnating

Question 4

It is essential for a clearing agent to be miscible both in _________ agent as well as ___________ agent.

Answer 4

dehydrating ; embedding

Question 5

Commonly used clearing agents are as follows :

Answer 5

Xylene
Toluene and Benzene
Chloroform
Carbon tetrachloride
Cedar wood oil (Histological)

Question 6

a clearing agent; It has a rapid action. Biopsy specimens of 3-4 mm thickness
are cleared in 2-4 hours.

Answer 6

Xylene

Question 7

In xylene, Immersion time must not be prolonged otherwise the tissue become _______

Answer 7

brittle.

Question 8

a clearing agent; that are similar in properties to xylene but are less damaging to the tissues on prolonged exposure.

Answer 8

Toluene and Benzene

Question 9

a clearing agent; It is slower in action but it causes less brittleness therefore tissue can be left in it overnight.

Answer 9

Chloroform

Question 10

a clearing agent; does not affect the refractive index of the tissue is not
rendered translucent and is expensive and inflammable.

Answer 10

Chloroform

Question 11

a clearing agent; It is good for treatment of delicate tissues as it has the least hardening effect.

Answer 11

Cedar wood oil (Histological):

Question 12

a clearing agent; is very slow in action and is very expensive.

Answer 12

Cedar wood oil (Histological):

Question 13

In Cedar wood oil (Histological), care should be taken not to confuse it with ____________- used with oil immersion lens.

Answer 13

cedar wood oil (microscopic)

Question 14

Techniques of clearing

If the tissue is being cleared in _______ or _________ it may be left overnight.

Answer 14

chloroform ; carbon tetrachloride

Question 15

Techniques of clearing

In automatic tissue processor ____ changes of ____ hour each are usually satisfactory.

Answer 15

three ; one

Question 16

Techniques of clearing

In _______, _______, ______ one change after 30-60 minutes is satisfactory to give a clear translucent appearance to the tissue.

Answer 16

Xylene, benzene or toluene

Question 17

It is the complete removal of clearing reagents by substitution of paraffin or any such similar media.

Answer 17

Impregnation

Question 18

Impregnation with paraffin wax takes place in an oven heated to _________ depending upon the melting point of the wax in use.

Answer 18

56-60°C

Question 19

Frequent check of the temperature of paraffin baths is required since temperature 5°C above the melting point of the paraffin will cause tissue _________ and __________

Answer 19

shrinkage and hardening

Question 20

Properties of paraffin wax

1. Easy to prepare large number of tissue blocks in comparatively _____ time.
2. Minimum _______ is required
3. It is ______ than other impregnating media
4. During staining there is very little ________ than other media.

Answer 20

short ; supervision ; cheaper ; difficulty

Question 21

(Points to be remembered during use of paraffin wax)

1. It should be free from ____, ____ and other foreign matter.

Answer 21

dust ; grit

Question 22

(Points to be remembered during use of paraffin wax)

2. It should not contain ______, which causes it to crystallize and turn it
   white.

Answer 22

water

Question 23

(Points to be remembered during use of paraffin wax)

3. The wax has to be _______ before use by use of ordinary filter paper.

Answer 23

filtered

Question 24

(Points to be remembered during use of paraffin wax)

4. ______ melting point waxes are hard to ribbon.

Answer 24

Higher

Question 25

For impregnation the wax oven has to be kept at high temperature, making the tissue hard, too low melting point wax may not be hard enough to support the tissue during cutting.

Answer 25

yes

Question 26

If the wax is overheated and remains in that state for a long time, it tends to ______ and become _______.

Answer 26

crystallize ; useless

Question 27

his is mixture of highly purified paraffin and several plastic polymers.

Answer 27

Paraplast

Question 28

Paraplast has greater elasticity than __________, therefore, the results are superior.

Answer 28

normal paraffin wax

Question 29

Paraplast ribbons well allowing almost wrinkle free serial sections to be cut with ease at ______ thickness.

Answer 29

4 micron

Question 30

should not be used for thin walled structures as it prevents complete expansion of the specimen.

Answer 30

Paraplast

Question 31

Good embedding medium in which thin walled structures can be sectioned satisfactorily.

Answer 31

Bioloid

Question 32

(Technique of impregnation) The tissue is transferred from clearing agent to ___________-.

Answer 32

molten paraffin wax

Question 33

(Technique of impregnation) The amount of wax should be ______ times the volume of tissue.

Answer 33

25-50

Question 34

(Technique of impregnation) The tissue must be submitted to ___ changes in wax.

Answer 34

3

Question 35

(Technique of impregnation) The temperature of the wax bath should be ______ above the melting point of wax.

Answer 35

2-3°C

Question 36

Time of impregnation Depends on the following 3 factors

Answer 36

1. The size and type of tissue 2. The clearing agent employed 3. The use of vacuum embedding oven.

Question 37

1. Size and type of tissue: The _____ the tissue the _____ will be the time required for wax to penetrate to the centre in addition a thick tissue has more of clearing agent so more changes of wax are necessary to remove it.

Answer 37

thicker ; longer

Question 38

1. Size and type of tissue: If even small amounts of clearing agents remains with the wax this will cause ________ and produce ______ of the sections during cutting.

Answer 38

crystallization ; crumbling

Question 39

1. Size and type of tissue: The type of tissue is also important since ____, _____, _____ needs twice as long as soft tissue like liver or kindly.

Answer 39

bone, skin, CNS

Question 40

1. Size and type of tissue: Tissue like muscle and fibrous tissue tends to overharden and become brittle in wax bath so the time for impregnation must be kept to a ______.

Answer 40

minimum

Question 41

1. Size and type of tissue: The reduction of time can be achieved by using ________________.

Answer 41

vacuum embedding medium

Question 42

2. Clearing agent employed Some clearing agents are more rapidly and easily cleared than other e.g. _____, _______ and ______ are easiest to remove, and ____ change of wax is normally sufficient; whereas for chloroform and carbon tetrachloride _____ changes are needed.

Answer 42

Xylene, benzene and toluene ; one ; 2-3

Question 43

3. Use of vacuum embedding oven With the use of normal paraffin oven, ___ changes of paraffin wax for a period of ______ are needed but by using vacuum embedding oven this time may be halved

Answer 43

2 ; 4 hours