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1. Histopath Lec > tissue processing technique (tissue prepartion and fixation) > Flashcards

tissue processing technique (tissue prepartion and fixation) Flashcards

1
Q

Method of fresh tissue examination

A

Teasing/dissociation
Squash preparation (crushing)
Smear preparation
Frozen section

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2
Q

Selected tissue specimen is immersed in a watch glass containing isotonic solution, carefully dissected and examined under the microscope.

A

Teasing/dissociation

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3
Q

Small piece of tissue < 1mm in diameter is forcibly compressed between two slides or with a cover slip.

A

Squash preparation (crushing)

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4
Q

useful in cytological examination.

A

Smear preparation

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5
Q

Smear preparation

A

Streaking
Spreading
Pull apart
Touch preparation

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6
Q

Specimen is directly and gently applied on a slide in zigzag motion using applicator stick or wire loop.

A

Streaking

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7
Q

Specimen is gently spread in slide into a moderately thick film.

A

Spreading

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8
Q

Suitable specimen for spreading smear preparation

A

Sputum
bronchial aspirates
thick mucoid secretion

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9
Q

A drop of secretion or sediment upon 1 slide and facing it to another slide.

A

Pull-apart

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10
Q

2 slides are pulled apart in a single uninterrupted motion.

A

Pull-apart

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11
Q

Specimen suitable for pull apart smear preparation

A

Serous fluid
sputum
GIT secretion
Blood preparation

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12
Q

Freshly cut tissue is brought into contact and pressed on the surface of a clean glass slide.

A

Touch preparation

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13
Q

Used in rapid tissue examination (cryostat procedure).

A

Frozen section

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14
Q

For rapid diagnosis in cases of emergency.

A

Frozen section

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15
Q

Tissue is hardened by freezing, cut frozen, and stained for microscopic examination.

A

Frozen section

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16
Q

The most critical step in histotechnology

A

Fixation

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17
Q

Defined as the alteration of tissues by stabilizing protein so resist changes such as degeneration, decomposition, putrefaction and tissue distortion.

A

Fixation

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18
Q

brings about crosslinking of proteins which produces denaturation or coagulation of proteins so that the semifluid state is converted into semisolid state.

A

fixative

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19
Q

To preserve the tissue in as life like manner as possible.
Preservation of morphologic and chemical integrity of tissue.

A

Primary aim of fixative

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20
Q

Hardening and solidification.
To protect from trauma or further handling, for easier cutting during gross examination.

A

Secondary aim of fixative

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21
Q

Main factors involved in fixation

A

Hydrogen ion concentration
Temperature
Thickness of section
Osmolality
Concentration
Duration of fixation

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22
Q

Temperature for
Routine
Electron microscopy

A

Room temp
0-4C

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23
Q

Hydrogen ion concentration for fixation

A

pH between 6 and 8

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24
Q

Thickness of section for electron microscopy
light microscopy

A

1-2 mm (squared)
2 cm(squared)

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25
Q

Osmolality for fixation

A

Slightly hypertonic solution (400-450 mOsm)

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26
Q

Concentration of formalin for fixation
Routine
Immuno-electron microscopy

A

10%
0.25%

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27
Q

Duration of fixation for

specimen obtained or remained in fixative over weekend

electron microscopy

A

2-6 hours
3 hours

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28
Q

Practical consideration of fixation

A

Speed
Rate of penetration
Volume
Duration of fixation

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29
Q

Rate of penetration of formalin

A

1mm/hour

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30
Q

volume of fixation most effective of tissue fixation

A

20 x tissue volume

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31
Q

Fixation can be hasten by using?

A

heat
vacuum
agitation
microwave

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32
Q

Factors that enhance fixation

A

Size and thickness - thinner
agitation
moderate heat (37C)

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33
Q

Factors the slows down fixation

A

Size and thickness - larger
Presence of mucus, blood, and fats
cold temperature

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34
Q

What are the simple chemical fixatives

A

Aldehyde fixative
Metallic fixative
Alcohol-based fixative
Potassium dichromate fixative
Picric acid fixative
Glacial acetic acid fixative
Acetone fixative
Osmium tetra oxide

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35
Q

What are the compound chemical fixatives

A

Micro-anatomical fixative
Cytological fixative
Histo-chemical fixative

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36
Q

What are the aldehyde fixatives

A

Formaldehyde (formalin)
10 % formol saline
10% neutral buffered formalin
Formol-corrosive
alcoholic formalin
glutaraldehyde

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37
Q

is a gas but is soluble in water to the extent of 37-40% w/v.

A

formaldehyde

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38
Q

formaldehyde is a gas but is soluble in water to the extent of 37-40% w/v. this solution of formaldehyde in water is called ___ or _____

A

formalin
full strength formalin

39
Q

one of the commonly used fixative in all laboratories since it is cheap, penetrates rapidly, and does not over harden the tissues.

A

formalin

40
Q

Time required for fixation
at toom temperature
for small biopsies
at 65C fixation occurs in

A

12 hours
4-6 hours
2 hours

41
Q

Recommended for CNS tissues and general post-mortem tissues.

A

10 % formol

42
Q

Ideal for most staining technique including silver impregnation.

A

10 % formol

43
Q

Best fixative for tissue containing iron pigments.

A

10 % neutral buffered formalin/phosphate buffered formalin

44
Q

Recommended for post-mortem tissues.

A

Formol-corrosive (formol-sublimate)

45
Q

Fixes lipids escpecially neutral fats and phospholipids
No need for ‘’washing out’’ steps

A

Formol-corrosive (formol-sublimate)

46
Q

Gendré’s fluid is a?

A

Alcoholic formalin fixative

47
Q

Used to fix sputum specimen
Can be both fixative and dehydrating agent

A

Alcoholic formalin fixative

48
Q

Suitable for in light microscopy in resin embedding and sectioning for electron microscopy.

A

Karnovsky’s fixative

49
Q

it is used alone or in combination with osmium tetroxide for electron microscopy.

A

Glutaraldehyde

50
Q

Recommended for enzyme histochemistry and electron microscopy

A

Glutaraldehyde

51
Q

What are the metallic fixative

A

Mercuric chloride
Zenkers fluid
Zenker-formol
Heidenhain’s susa
B-5 fixative
Chromic acid
Orth’s fluid
Lead fixative

52
Q

most common metallic fixative

A

Mercuric chloride

53
Q

rarely used alone because it causes shrinkage of the tissue. Produces black precipitates (mercuric deposits).

A

Mercuric chloride

54
Q

Mercuric acids are removed by immersing the tissue before staining to Lugol’s iodine for 5 mins and 5 % Na thiosulfate for 5 mins this process is known as

A

Dezenkerization.

55
Q

it fixes the cytoplasm without precipitation.

A

Potassium dichromate

56
Q

Preserves lipids and mitochondria

A

Potassium dichromate

57
Q

precipitate all proteins
excellent for glycogen demonstration
suitable for aniline dyes

A

Picric acid

58
Q

Examples of Picric acid

A

Bouin’s solution
Brasil’s Icoholic picroformol fixative

59
Q

solidifies at 17˚C
it causes the cells to swell hence can never be used alone but should be used with fixatives causing cell shrinkage.

A

Glacial Acetic acid

60
Q

Alcohol-based fixatives

A

100 % methyl alcohol
95 % isopropyl alcohol
70 – 100 % ethyl alcohol
Carnoy’s fuid

61
Q

used as both fixative and dehydrating agent

A

Alcohol

62
Q

preserves some proteins in relatively undenatured state so that it can be used for immunofluorescence or some histochemical methods to detect certain enzymes.

A

ethanol

63
Q

used for fixing blood and bone marrow smears.

A

methyl alcohol

64
Q

it is a strong oxidizing agent ( pale yellow powder)

A

Osmium tetroxide

65
Q

used for neurological tissues. e.g. myelin sheath.

A

Osmium tetroxide

66
Q

Example of Osmium Tetroxide

A

Flemming’s solution
Flemming’s solution without acetic acid

67
Q

use in cold temperature
demonstrates some tissue enzymes like phosphatases and lipases

A

Acetone

68
Q

fixative agent for rabies diagnosis (Negri bodies)

A

Acetone

69
Q

such fixatives preserves the anatomy of the tissue.

A

MICROANATOMICAL FIXATIVES

70
Q

MICROANATOMICAL FIXATIVES

A

10% formalin
heidenhain susa
zenkers fluid
zenker formal (helly fluid)
Bouin’s fixative
B5 fixative

71
Q

Recommended for fixing small pieces of liver, spleen, connective tissue fibers and nuclei.

A

Zenker’s fluid

72
Q

Suitable for pituitary gland, bone marrow and blood containing organs such s spleen and liver.

A

Zenker-Formol (Helly’s solution)

73
Q

Recommended for pituitary and embryo biopsies.

A

Bouin’s fixative

74
Q

Recommended for skin tumor biopsies.

A

Heidenhain Susa solution

75
Q

Commonly used for bone marrow biopsies.

A

B5 fixative

76
Q

such fixation are used to preserve intracellular structures or inclusion.

A

CYTOLOGICAL FIXATIVES

77
Q

Nuclear fixatives

A

Carnoy’s fluid
New comer’s fluid
Flemming’s fluid

78
Q

Cytoplasmic Fixatives

A

Orth’s fluid
Flemmings fluid withou acetic acid
Regard’s fluid

79
Q

The most rapid fixative.
Recommended for fixing chromosome, lymph glands and urgent biopsies.

A

Carnoy’s fluid

80
Q

Recommended for fixing mucopolysaccharides and nuclear proteins.

A

Newcomer’s fluid

81
Q

Serves as both nuclear and histochemical fixatives.

A

Newcomer’s fluid

82
Q

Recommended for tissue necrosis
Preserves myelin sheath better
Demonstrate rickettsiae

A

Orth’s fluid

83
Q

Recommended for demonstration of chromatin, mitochondria, mitotic figures, golgi bodies, RBC and colloid containing tissues.

A

Regard’s fluid

84
Q

fixative used to preserve the chemical nature of the tissue for further analysis. Used in frozen section

A

HISTOCHEMICAL FIXATIVES

85
Q

HISTOCHEMICAL FIXATIVES

A

Absolute ethyl alcohol
Acetone
10% formol saline
Newcomer’s fluid

86
Q

Physical method of fixation

A

Heat fixation
Microwave fixation
Freeze drying and freeze substitution

87
Q

Heat primarily used to accelerate other forms of fixation.

A

Heat fixation

88
Q

What fixation
Thermal coagulation of tissue proteins for rapid diagnosis.
Usually employed for frozen tissue section and bacteriologic smears.

A

Heat fixation

89
Q

What fixation
increase the movement of molecule to accelerate fixation.

A

Microwave fixation

90
Q

Useful in preserving neurochemical substances in brain such acetylcholine.

A

Microwave fixation

91
Q

Microwave fixation treated tissue at what temperature

A

50C

92
Q

rapid freezing of tissue (-160 to -180 C) and then dehydrated in a vacuum at -30 C to -40 C to remove ice water molecules.

A

Freeze drying

93
Q

fixed in Rossman’s formula or in 1 % acetone to dehydrate the tissue.

A

Freeze substitution

1. Histopath Lec (3 decks)

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