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mt > IMPREGNATION AND EMBEDDING > Flashcards

IMPREGNATION AND EMBEDDING Flashcards

1
Q

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.

A

IMPREGNATION

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2
Q

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

A

EMBEDDING, CASTING OR BLOCKING

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3
Q

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

A

paraffin wax

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4
Q

paraffin wax melting point

A

39-68 deg celsius

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5
Q

paraffin wax is a rapid process, prepared within ___ hours

A

24

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6
Q

Tissue blocks and unstained mounted sections maybe stored for ___

A

indefinite period of time

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7
Q

disadvantage of paraffin wax

A

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

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8
Q

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

A

bones, teeth, brain, eyes

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9
Q

not recommended for fatty tissues

A

paraffin

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10
Q

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

A

oven or incubator at 55 to 60 degree celsius

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11
Q

in modified paraffin waxes, the increase hardness is due to

A

stearic acid

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12
Q

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

A

phenanthrene

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13
Q

enhance tissue wax adhesion

A

modified paraffin wax

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14
Q

modified paraffin wax is added with

A

Added with piccolyte 115, plastic polymers and dimethyl sulphoxide.

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15
Q

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

A

impregnation

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16
Q

Factors Affecting Paraffin Wax Impregnation

A
  1. Nature of tissues
  2. Size of tissues
  3. Type of clearing agent
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17
Q

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

A

celloidin impregnation

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18
Q

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

A

Compound embedding unit

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19
Q

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

A

Plastic embedding rings and base mold

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20
Q

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.

A

Leuckhart’s embedding mold

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21
Q

Cheap and easy to make

A

Paper boat

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22
Q

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

A

Peel-Away

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23
Q

common wax melting points

A

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

24
Q

routine work wax melting point

A

The 56oC wax is usually used in routine work

25
Q

Hard tissues require wax with higher _____ than ____ tissues

A

Hard tissues require wax with higher melting point than soft tissues

26
Q

3 ways of paraffin impregnation and embedding

A

By manual processing
By automatic processing
By vacuum embedding

27
Q

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

A

4; 15; clearing agent

28
Q

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

A

fresh solution of melted paraffin for 3 hours

29
Q

Fixes, dehydrates, clears and infiltrates tissues

A

automatic processing

30
Q

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

A

2 to 3

31
Q

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

A

agitation

32
Q

example of automatic processing

A

Elliott Bench-Type Processor

33
Q

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

A

automatic processing

34
Q

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

A

changed

35
Q

most critical stage in automatic processing

A

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

36
Q

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

A

since tissue is in paraffin

37
Q

Clearing agents and dilute ethanol should be changed at least ____

A

once a week

38
Q

in automatic processing, spillage should be ___.

A

avoided

39
Q

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

A

appropriate

40
Q

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

A

3 degrees

41
Q

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

A

vacuum embedding

42
Q

vacuum embedding is used for

A

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

43
Q

time required is reduced by ___ in vacuum embedding

A

25-75%

44
Q

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

A

2 to 4 degree celsius

45
Q

SUBSTITUTES FOR PARAFFIN WAX

A

Paraplast
Ester wax
Water soluble media (polyethylene glycols)

46
Q

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

A

polyethylene glycols

47
Q

Includes agar, gelatine, sodium carboxymethyl cellulose and polyvinyl alcohol

A

aqueous media

48
Q

4 main types of mold-embedding

A

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.

49
Q

Most important step in embedding

A

orienting tissue in the block

50
Q

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

A

missed or damaged

51
Q

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

A

down

52
Q

Elongated tissues are placed ______ across the block

A

diagonally

53
Q

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

A

cyst, fallopian tubes, and GIT

54
Q

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

A

right

55
Q

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

A

long axis; randomly

mt (54 decks)

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