IMPREGNATION AND EMBEDDING

Question 1

Is the process whereby the clearing agent is completely removed from the tissue and replaced by a medium that will completely fill all the tissue cavities, thereby a firm consistency to the specimen.

Answer 1

IMPREGNATION

Question 2

Process whereby the impregnated tissue is placed into a precisely arranged position in a mold containing a medium

Answer 2

EMBEDDING, CASTING OR BLOCKING

Question 3

Is a polycrystalline mixture of solid hydrocarbons
Simplest, most common and best embedding medium
Individual serial sections may be cut with ease

Answer 3

paraffin wax

Question 4

paraffin wax melting point

Answer 4

39-68 deg celsius

Question 5

paraffin wax is a rapid process, prepared within ___ hours

Answer 5

24

Question 6

Tissue blocks and unstained mounted sections maybe stored for ___

Answer 6

indefinite period of time

Question 7

disadvantage of paraffin wax

Answer 7

Overheated makes tissue brittle

Prolonged will cause excessive tissue shrinkage and hardening

Inadequate impregnation promotes retention of clearing agents, tissues become soft and shrunken, tissue blocks crumble when sectioned and break up when floated in water bath

Question 8

what are difficult to impregnate and needs long immersion for proper support otherwise they will crumble

Answer 8

bones, teeth, brain, eyes

Question 9

not recommended for fatty tissues

Answer 9

paraffin

Question 10

After completely cleared, the tissue is submerged in 2 or more changes of melted paraffin wax either in

Answer 10

oven or incubator at 55 to 60 degree celsius

Question 11

in modified paraffin waxes, the increase hardness is due to

Answer 11

stearic acid

Question 12

in modified paraffin waxes, the decrease melting point is due to

Answer 12

phenanthrene

Question 13

enhance tissue wax adhesion

Answer 13

modified paraffin wax

Question 14

modified paraffin wax is added with

Answer 14

Added with piccolyte 115, plastic polymers and dimethyl sulphoxide.

Question 15

Paraffin wax impregnation is the simplest, most common and best embedding medium used for routine processing.

Answer 15

impregnation

Question 16

Factors Affecting Paraffin Wax Impregnation

Answer 16

1. Nature of tissues
2. Size of tissues
3. Type of clearing agent

Question 17

Recommended for neurological tissues
Does not require heating during processing; hence, producing minimum shrinkage and tissue distortion especially for cutting large bone tissues
Frozen section technique cannot be done

Answer 17

celloidin impregnation

Question 18

Made up of series of interlocking plates resting on a flat metal base, forming several compartments.

Answer 18

Compound embedding unit

Question 19

Consist of a special stainless steel base mold fitted with a plastic embedding ring.

Answer 19

Plastic embedding rings and base mold

Question 20

Consists of 2 L-shaped strips of heavy brass or metal arranged on a flat metal plate and which can be moved to adjust the size of the mold to the size of the specimen.

Answer 20

Leuckhart’s embedding mold

Question 21

Cheap and easy to make

Answer 21

Paper boat

Question 22

Peeled off one at a time, as soon as the wax has solidified

Answer 22

Peel-Away

Question 23

common wax melting points

Answer 23

45C, 52oC, 56 oC and 58oC.

Question 24

routine work wax melting point

Answer 24

The 56oC wax is usually used in routine work

Question 25

Hard tissues require wax with higher _____ than ____ tissues

Answer 25

Hard tissues require wax with higher melting point than soft tissues

Question 26

3 ways of paraffin impregnation and embedding

Answer 26

By manual processing By automatic processing By vacuum embedding

Question 27

in manual processing, At least ____ changes of waxes are required at ____ minutes interval (for removal of ____)

Answer 27

4; 15; clearing agent

Question 28

in manual processing, Specimen is immersed into another_______ for___ hours for completely embedding/casting

Answer 28

fresh solution of melted paraffin for 3 hours

Question 29

Fixes, dehydrates, clears and infiltrates tissues

Answer 29

automatic processing

Question 30

in automatic processing, only ___ to ___ changes of waxes are required

Answer 30

2 to 3

Question 31

in automatic processing, there is a constant ____ w/c accelrates and improve tissue penetration

Answer 31

agitation

Question 32

example of automatic processing

Answer 32

Elliott Bench-Type Processor

Question 33

The machine is mounted on rollers to permit the turning of platforms and easy access to beakers and wax baths

Answer 33

automatic processing

Question 34

The presence of odor in the clearing agent during final paraffin wax bath indicates that the paraffin should be ____

Answer 34

changed

Question 35

most critical stage in automatic processing

Answer 35

Dehydrating agents should be changed regularly since it is the most critical stage

Question 36

In automatic tissue processing, inadequate dehydration is diificult to correct ____

Answer 36

since tissue is in paraffin

Question 37

Clearing agents and dilute ethanol should be changed at least ____

Answer 37

once a week

Question 38

in automatic processing, spillage should be ___.

Answer 38

avoided

Question 39

fluid and wax container in automatic processing should be filled to the ____ level

Answer 39

appropriate

Question 40

Wax bath thermostats should be at least ____ above melting point of the wax.

Answer 40

3 degrees

Question 41

Fastest result Involves wax impregnation under negative atmospheric pressure inside a embedding oven to hasten removal of air bubbles and clearing agent from the tissue block thereby promoting a more rapid wax impregnation Removes residual air bubbles in lungs

Answer 41

vacuum embedding

Question 42

vacuum embedding is used for

Answer 42

For urgent biopsies, brain connective tissue, decal bone eyes spleen CNS

Question 43

time required is reduced by ___ in vacuum embedding

Answer 43

25-75%

Question 44

Controlled water jacket usually maintained at _____ above melting point of wax

Answer 44

2 to 4 degree celsius

Question 45

SUBSTITUTES FOR PARAFFIN WAX

Answer 45

Paraplast Ester wax Water soluble media (polyethylene glycols)

Question 46

are used to investigate heat-and solvent-labile lipids and proteins

Answer 46

polyethylene glycols

Question 47

Includes agar, gelatine, sodium carboxymethyl cellulose and polyvinyl alcohol

Answer 47

aqueous media

Question 48

4 main types of mold-embedding

Answer 48

Traditional Leuckart or dimmock irons or metal containers Peel-away system using disposable plastic molds Embedding rings or cassette bases w/c become integral part of the block and serve as the block holder in the microtome.

Question 49

Most important step in embedding

Answer 49

orienting tissue in the block

Question 50

Improper placement may result in ____ or ___ tissue portions during microtomy

Answer 50

missed or damaged

Question 51

Tissues are blocked with the surface to be cut facing ___ in a mold

Answer 51

down

Question 52

Elongated tissues are placed ______ across the block

Answer 52

diagonally

Question 53

Tubular and walled specimens such as _____ are embedded en face so as to provide cross sections showing all tissue layers

Answer 53

cyst, fallopian tubes, and GIT

Question 54

Tissues w/ epithelial surface such as skin are embedded to provide sections in a plane at a ____ angle to the surface

Answer 54

right

Question 55

Multiple tissue pieces are aligned across the _____ and the center of the mold are not placed ___.

Answer 55

long axis; randomly