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HISTOPATHOLOGY > PREFINALS: IMPREGNATION AND EMBEDDING > Flashcards

PREFINALS: IMPREGNATION AND EMBEDDING Flashcards

1
Q

AKA Infiltration

A

IMPREGNATION

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2
Q

Removal of clearing agent from the tissue and replacing it with the infiltrating media

A

IMPREGNATION

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3
Q

This infiltrating media will completely fill all tissue cavities, thus giving firm consistency, as well as allow easy handling and cutting of thin tissue

A

IMPREGNATION

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4
Q

Incomplete Impregnation =

A

Airholes in tissue sections

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5
Q

Main factors: method of impregnation, nature and size of tissue, clearing agent used

A

IMPREGNATION

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6
Q

Types of Tissue Impregnation and Embedding Media:

A
  1. Paraffin impregnation
  2. Celloidin (Colloidin) impregnation
  3. Gelatin impregnation
  4. Plastic
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7
Q

Simplest, common and best media for routine processing

A

Paraffin

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8
Q

ADV: sections are cut easily without distortion; very rapid (24hrs); permits many staining procedures;

A

Paraffin

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9
Q

DADV: not for fatty tissues; must fully impregnate the tissue to avoid tissue crumbling

A

Paraffin

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10
Q

Paraffin
Melting point for routine work:

A

56C

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11
Q

Paraffin
Never overheat (>60OC):

A

causes brittleness, shrinkage, hardening; destruction of lymph tissue

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12
Q

maintain at 2 to 5C higher than MP of wax

A

Paraffin oven

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12
Q

Wax must be filtered first using coarse filter paper such as Green’s No. 904 in wax oven at 2OC higher than MP of wax

A

Paraffin

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12
Q

Used pure

A

Paraffin

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13
Q

Reusable only once, but remove water first by boiling to 100-105OC

A

Paraffin

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14
Q

Methods of Paraffin Impregnation:

A
  1. Manual
  2. Automatic
  3. Vacuum Embedding
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15
Q

 Atleast 4 changes of paraffin every 15 minutes

A

Manual

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16
Q

Uses machines like Autotechnicon and Elliot Bench-Type Processor, which fixes, dehydrates, clears, and infiltrates tissues

A

Automatic

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17
Q

Infiltration is usually at stations 11 and 12

A

Autotechnicon

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18
Q

ADV: Has constant agitation  speedy procedure

A

Autotechnicon

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19
Q

NOTE: Any odor in clearing agent indicates that the paraffin wax should be changed

A

Autotechnicon

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20
Q

Wax bath thermostat should be set atleast 3 degrees above the MP of paraffin

A

Autotechnicon

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21
Q

Fastest (25-75% reduction of usual impregnation time)

A

Vacuum Embedding

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22
Q

Uses embedding oven with negative atmospheric pressure  rapid removal of air bubbles (e.g. lungs) and clearing agent rapid infiltration

A

Vacuum Embedding

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23
Q

For urgent biopsies, delicate tissues (e.g. CNS, eyes)

A

Vacuum Embedding

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24
Q

Paraffin Wax Substitutes:

A
  1. Paraplast
  2. Embeddol
  3. Bioloid
  4. Tissue Mat
  5. Ester Wax
  6. Water Soluble Waxes (Polyethylene glycol)
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25
Q

Mixture of pure paraffin and synthetic plastic polymer (Dimethyl sulfoxide); more elastic and resilient

A

Paraplast

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26
Q

MP: 56-57C

A

Paraplast

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27
Q

less brittle, and less compressible (MP: 56-57OC)

A

Embeddol

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28
Q

semisynthetic; for embedding of eyes

A

Bioloid

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29
Q

has rubber

A

Tissue Mat

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30
Q

Water insoluble but soluble in 95% ethanol, thus prior clearing is not needed

A

Ester Wax

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31
Q

MP: 46-48C

A

Ester Wax

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32
Q

Harder than paraffin thus used with sliding/sledge-type microtome

A

Ester Wax

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33
Q

But Cellosolve, and xylene may be used if indicated

A

Ester Wax

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34
Q

MP: 38-42OC or 45-56OC

A

Water Soluble Waxes (Polyethylene glycol)

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35
Q

Water Soluble Waxes (Polyethylene glycol) most common:

A

Carbowax

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36
Q

Carbowax
absorbs water; no need for dehydration and clearing

A

Hygroscopic

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37
Q

Easily dissolved in water, thus sections are difficult to float out and mount
[Remedy: add soap to water, or 10% polyethylene glycol 900 in water]

38
Q

Neutral fats and lipids can be demonstrated

39
Q

Not exposed to too much heat, thus for enzyme histochemistry

40
Q

AKA colloidin

41
Q

Purified form of nitrocellulose/gun cotton

42
Q

Concentration: in 2%, 4%, 8% dissolved in equal parts of ether and ROH

42
Q

Specimen with large and hollow cavities which tend to collapse; hard and dense tissues; neurologic tissues

43
Q

ADV: Does not require heat for processing; rubbery

44
Q

DADV: very slow (days to weeks)

45
Q

Celloidin Methods:

A
  1. Wet Celloidin
  2. Dry Celloidin
46
Q

For bones, brain, teeth

A

Wet Celloidin

46
Q

Wet Celloidin procedure:

A
  1. Fixation & Dehydration
  2. Place tissue in ether-alcohol
  3. Thin celloidin
  4. Medium celloidin
  5. Thick celloidin
  6. Remove specimen and the put it in fresh thick celloidin
  7. Keep in jar or dessicator until ether-alcohol
    evaporates
  8. Store tissue block in 70%-80% alcohol
47
Q

No fingerprint marks on
surface of tissue block

A

Complete impregnation

48
Q

For whole eye sections

A

Dry Celloidin

48
Q

Uses Gilson’s mixture (equal parts of chloroform and cedar wood oil) for storage, instead of 70% to 80% alcohol

A

Dry Celloidin

49
Q

Has lower viscosity, thus can be used in high
concentrations, and rapid tissue penetration

A

Nitrocellulose Method/Low Viscosity Nitrocellulose (LVN)

50
Q

*

ADV: Harder tissue block, thus thinner sections are possible

A

Nitrocellulose Method/Low Viscosity Nitrocellulose (LVN)

51
Q

DADV: Explosive when dry d/t nitrates

A

Nitrocellulose Method/Low Viscosity Nitrocellulose (LVN)

52
Q

Nitrocellulose Method/Low Viscosity Nitrocellulose (LVN)

(e.g. oleum ricini or castor oil) is needed
to prevent tissue cracking in chrome-mordanted tissues

A

Plasticizer

53
Q

Rarely used

54
Q

For histochemical, enzyme studies, and frozen sections

55
Q

ADV: Water soluble (no dehydration and clearing needed)

56
Q

DADV: may decay

57
Q

Gelatin TSE must be:

A

<2-3mm thick

57
Q

Gelatin Procedure:

A
  1. Wash out of fixative
  2. Put tissue in 10% gelatin with 1% phenol
  3. 20% gelatin with 1% phenol
  4. Fresh 20% gelatin with 1% phenol
  5. Cool in refrigerator
  6. 10% formalin
58
Q

Gelatin
TSE:IMPERGNATING AGENT ratio is set at

59
Q

Gelatin

must be added to prevent molds

60
Q

AKA Casting, Blocking

61
Q

Placing the impregnated tissue into a mold with embedding media, and then allowing the media to solidify

62
Q

Arrangement of the tissue in a precise position in the mold during embedding

A

Orientation

63
Q

Surface to be cut should be parallel to bottom of the mold

64
Q

Molds should bear the accession number

65
Q

EMBEDDING Procedure:

A

Put tissue with label on a mold, immerse them in melted paraffin at 5-10 OC higher than MP of wax, then rapidly cool in a refrigerator at -5
OC, or in cold water

66
Q

Embedding Molds:

A
  1. Leuckhart’s Embedding mold
  2. Compound embedding unit
  3. Plastic embedding rings and base molds
  4. Disposable molds
67
Q

L-shaped strips of heavy brass and metal; reusable and adjustable

A

Leuckhart’s Embedding mold

68
Q

Interlocking plates resting on flat metal base; for batch embedding

A

Compound embedding unit

69
Q

Plastic embedding rings and base molds

A

Special stainless steel base mold fitted with
a plastic embedding ring (serves as block
holder during cutting)

70
Q

has paraffin reservoir, tissue
tank, warm plate and cold plate (-5C)

71
Q

(thin plastic mold)

72
Q

Disposable molds:

A
  1. Peel-away
  2. Plastic Ice tray
  3. Paper boats
73
Q

(inner mold smeared with
glycerin or liquid paraffin),

A

Plastic Ice tray

74
Q

Other Embedding Methods:

A
  1. Double embedding method
  2. Plastic (Resin) embedding
75
Q

celloidin first, then paraffin; for large blocks of dense tissues; obsolete

A

Double embedding method

76
Q

Plastic (Resin) embedding Classes:

A
  • Epoxy
  • Polyester
  • Acrylic Plastics
76
Q

For High resolution light microscopy of thinner than usual sections, renal biopsies, BM biopsies

A

Plastic (Resin) embedding

76
Q

For electron microscopy

77
Q

Most widely applied, but carcinogenic due to
vinylcyclohexane dioxide (VCD) component

77
Q

Epoxy Types:

A
  • Bisphenol A (Araldite)
  • Glycerol (Epon)
  • Cyclohexene Dioxide (Spurr)
78
Q

slow

A

Bisphenol A (Araldite)

79
Q

low viscosity

A

Glycerol (Epon)

80
Q

very low viscosity; fastest

A

Cyclohexene Dioxide (Spurr)

80
Q

For electron microscopy; seldom used

81
Q

For High resolution light microscopy

A

Acrylic Plastics

82
Q

E.g., polyglycol methacrylate (GMA), methyl metacrylate (MMA)

A

Acrylic Plastics

83
Q

catalyst; forms radicals, which are
site for polymerization

A

Benzoyl peroxide

84
Q

Acrylic plastics must be stored in dark bottles to prevent radical formation and premature polymerization

A

Acrylic Plastics

85
Q

Embedding media may be stained, thus use hydrophobic MMA

A

Acrylic Plastics

HISTOPATHOLOGY (13 decks)

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