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MT6321 > 02 Fixation > Flashcards

02 Fixation Flashcards

1
Q

first step in histotechnology

A

fixation

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2
Q

chemical process by which biological tissues are preserved from decay

A

fixation

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3
Q

process of preserving cells and tissue constituents in a life-like manner

A

fixation

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4
Q

basic mechanism in fixation

(additive / non-additive)

cross linking fixatives

A

additive

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5
Q

basic mechanism in fixation

(additive / non-additive)

chemical constituent taken into the cell, forming molecular complexes and stabilizing proteins

A

additive

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6
Q

basic mechanism in fixation

(additive / non-additive)

formalin, mercury, osmium tetroxide

A

additive

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7
Q

basic mechanism in fixation

(additive / non-additive)

fixing agent is not incorporated into the tissue

A

non-additive

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8
Q

basic mechanism in fixation

(additive / non-additive)

alteration of tissue composition by removing bound water molecule at hydrogen bonds within protein molecules

A

non-additive

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9
Q

basic mechanism in fixation

(additive / non-additive)

stabilizes proteins by forming crosslinks after water molecule removal

A

non-additive

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10
Q

satisfactory fixation occurs at what pH level?

A

6-8

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11
Q

high acidity ___ (increases/decreases) effectiveness

A

decreases

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12
Q

what is the relationship of temperature to the diffusion into the tissue?

A

direct (increased temp = increased diffusion)

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13
Q

what is the relationship of diffusion into the tissue and rate of chemical reaction between the fixative and tissue elements?

A

direct

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14
Q

temperature of fixation of surgical specimens

A

room temp

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15
Q

the fixation of surgical specimens can be followed by further fixation at what temperature after fixating it at room temperature?

A

40-45C

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16
Q

temperature of fixation:

electron microscopy

A

0-4C

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17
Q

temperature of fixation:

mast cells for EM

A

room temp

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18
Q

T/F: nucleic acids easily react with fixatives at room temp

A

F (do not react)

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19
Q

chemical reactions are rapid at ___ (low/high) temp

what temp?

A

high
60-65C

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20
Q

the thickness of the section to be fixed should be ___

A

1-2mm for EM
2cm for light microscopy

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21
Q

the brain is usually suspended whole in ___ buffered formalin for ___ weeks to ensure fixation and some hardening prior to secitoning

A

10%
2-3

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22
Q

hypertonic solutions give rise to ___ ___

A

cell shrinkage

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23
Q

isotonic and hypotonic fixatives cause ___ and ___ ___

A

swelling
poor fixation

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24
Q

the best results is usually obtained using slightly ___ (osmolality) solutions

what mOsm?

A

hypertonic
400-450

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25
Q

give the concentration of fixatives:

formaldehyde

A

10%

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26
Q

give the concentration of fixatives:

glutaraldehyde

A

3%

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27
Q

presence of buffer causes polymerization of ___, with consequent ___ (increase/decrease) in its effective concentration

A

aldehyde
decrease

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28
Q

give the concentration of fixatives:

glutaraldehyde for immunoelectrochemistry

A

0.25%

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29
Q

primary fixation in buffered formalin is usually carried out for ___ hours during the day the specimen is obtained

A

2-6

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30
Q

___ fixation may cause shrinkage and hardening of the tissue and may severely inhibit enzyme activity and immunological reaction

A

prolonged fixation

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31
Q

the specimen should be placed in a fixative solution as soon as it is removed from the body to prevent ___ and ___

A

autolysis and putrefaction

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32
Q

the volume of fixative should be ___ times the volume of the tissue to be fixed

A

10-25

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33
Q

the maximum effectiveness of fixation is noted to be ___ times the tissue volume

A

20

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34
Q

fibrous organ take ___ (longer/shorter) than small or loosely textured tissues such as biopsies or scrapings

A

longer

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35
Q

fixation time can be cut down using ___, ___, ___, or ___

A

heat
vacuum
agitation
microwave

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36
Q

to maintain an adequate fixation time of 4-6 hours, the tissue size must be ___ square

A

2cm

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37
Q

T/F: refrigeration is used to slow down decomposition if the tissue that needs to be photographed and cannot be fixed immediately

A

T

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38
Q

classification of fixative:

made up only of one substance

A

simple fixative

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39
Q

classification of fixative:

two or more fixatives to obtain optimal combined effect

A

compound

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40
Q

aldehyde fixatives used (2)

A

formaldehyde
glutaraldehyde

rmmbr: these are simple fixatives!

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41
Q

metallic fixatives used (3)

A

mercuric chloride
chromate fixatives
lead fixatives

(M-C-L)

rmmbr: these are simple fixatives!

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42
Q

classification of fixative:

preserve specific parts and particular microscopic elements

A

cytologic fixatives

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43
Q

simple fixatives used (6)

A

picric acid
acetic acid
acetone
alcohol
osmium tetroxide
heat

(P-A-A-A-O-H)

44
Q

microanatomical fixatives used for general microscopic study of tissue structures (8)

A

10% formol saline
10% neutral buffered formalin
Heidenhain’s Susa
Formol Sublimate (formol corrosive)
Zenker’s solution
Zenker-formol (Helly’s solution)
Bouin’s solution
Brasil’s solution

45
Q

composition of Helly’s solution

A

Zenker-formol

46
Q

nuclear fixatives that use glacial acetic acid as primary component (5)

A

Carnoy’s fluid
Heidanhain’s susa
Bouin’s fluid
Newcomer’s fluid
Flemming’s fluid

(C-He-Bo-Ne-Fl)

47
Q

cytoplasmic fixatives (5)

A

Flemming’s fluid without acetic acid
Helly’s fluid
Formalin with Post-chroming
Regaud’s Fluid (moller’s fluid)
Orth’s fluid

48
Q

histochemical fixatives that preserve chemical constituents of cells and tissues (4)

A

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

49
Q

type of fixation used for lipid fixation

A

aldehyde fixatives

50
Q

type of fixation for carbohydrates that allow better retention

A

alcoholic fixatives

51
Q

arrange the following in order of DECREASING speed of penetration:

acetic acid
osmium tetroxide
picric acid
formaldehyde
ethyl/methyl alcohol
mercuric chloride

A

formaldehyde > acetic acid > mercuric chloride > ethyl/methyl alcohol / osmium tetroxide > picric acid

(F-A-M-E-O-P)

52
Q

this type of fixative form cross-links between proteins, creating a gel, thus retaining cellular constituents in their in vivo relationships to each other

A

aldehyde fixatives

53
Q

this fixative is produced from oxidation of methyl alcohol

A

formaldehyde

54
Q

fixation time of formaldehyde

A

24 hrs

55
Q

fixative for routine paraffin sections, EM, histochemistry, & enzyme studies

A

10% formalin

56
Q

diluent of 10% formol-saline

A

10% NaCl solution

57
Q

used as a fixative of CNS tissues

A

10% formol-saline

58
Q

fixation time of formol-saline and its optimal temperature (2)

A

24 hrs at 35C
48 hrs at RT

59
Q

fixative used for the preservation and storage of surgical, post-mortem, and research specimen

A

10% neutral buffered formalin

60
Q

fixation time of 10% neutral buffered formalin

A

2-4 hrs

61
Q

fixative recommended for routine post-mortem tissues

A

formol-corrosive

62
Q

components of 10% neutral buffered formalin

A

3.5 g sodium dihydrogen phosphate
6.5 g disodium hydrogen phosphate
100 mL 40% formaldehyde
900 mL distilled water

63
Q

components of 10% formol-saline

A

100 mL 40% formaldehyde
9 g NaCl
900 mL distilled water

64
Q

components of formol-corrosive

A

90 mL saturated aqueous mercuric chloride
10 mL formaldehyde

65
Q

fixative time of formol-corrosive

A

3-24 hrs

66
Q

this fixative brightens cytoplasmic and metachromatic stains

A

formol-corrosive

67
Q

this fixative bind with sulfhydryl groups in acidic solutions

A

metallic fixatives

68
Q

an excellent trichome stain and is included in most compound fixatives

A

5-7% mercuric chloride

69
Q

in 5-7% mercuric chloride, pigments are removed by treatment with iodide solution in ___

A

95% alcohol

70
Q

components of 5-7% mercuric chloride

A

5 g mercuric chloride
2.5 g potassium dichromate
1 g sodium sulfate
100 mL distilled water

71
Q

fixative for liver, spleen, connective tissue fibers, and nuclei

A

Zenker’s fluid

72
Q

fixation time of Zenker’s fluid

A

12-24 hrs

73
Q

this fixative permits brilliant staining of nuclear and connective tissue fibers

A

Zenker’s fluid

74
Q

this fixative lyses RBC and can make tissues brittle

A

Zenker’s fluid

75
Q

components of Zenker’s fluid

A

95 mL stock solution
5 mL glacial acetic acid 5mL

76
Q

fixative used for pituitary gland, bone marrow, and blood containing organs like spleen and liver

A

Zenker-formol

77
Q

fixative recommended for tumor biopsies of the skin

A

Heidenhain’s susa solution

78
Q

fixation time of Heidenhain’s susa solution

A

3-12 hrs

79
Q

fixative commonly used for bone marrow biopsies

A

B-5 fixative

80
Q

fixation time of B-5 fixative

A

1-2 hrs

81
Q

this fixative preserves carbohydrates and precipitates all proteins; but may produce sub-oxide precipitates

A

1-2% chromic acid

82
Q

this fixative preserves lipids and mitochondria

A

3% potassium dichromate

83
Q

fixation time of Regaud’s fluid

A

12-48 hrs

84
Q

fixative recommended for demonstration of chromaffin tissues, mitochondria, mitotic figures, golgi bodies, RBC, and colloid-containing tissues

A

Regaud’s fluid

85
Q

components for Regaud’s fluid

A

80 mL 3% potassium dichromate
20 mL 40% formaledhyde

86
Q

fixation time of Orth’s fluid

A

36-72 hrs

87
Q

this fixative is recommended for study of early degenerative processes and tissue necrosis

A

Orth’s fluid

88
Q

fixative recommended for acid mucopolysaccharides and fixes connective tissue mucin

A

4% lead acetate

89
Q

T/F: the mechanism of picric acid as a fixative is still unknown

A

T

90
Q

T/F: picric acid is insoluble in water

A

F

91
Q

the yellow color caused by picric acid can be removed by ___ ___ or washing with ___

A

lithium carbonate
50-70% ethanol

92
Q

fixative that penetrates and fixes small tissue rapidly

A

1% picric acid solution

93
Q

fixative that is excellent for glycogen demonstration and suitable for aniline stains

A

1% picric acid solution

94
Q

1% picric acid solution is not suitable for ___ as it causes crumbling when the sections are cut

A

frozen sections

95
Q

preferred fixative for connective tissue staining

A

Bouin’s solution

95
Q

fixative that is excellent for soft and delicate tissues with minimal distortion of microanatomical structures

A

Bouin’s solution

96
Q

a picric acid fixative that is less messy than Bouin’s solution

A

Brasil’s alcoholic picroformol fixative

97
Q

a fixative that is normally used in conjunction with other fixatives to form a compound solution

A

glacial acetic acid

98
Q

T/F: alcohol is used both for fixation and dehydration

A

T

99
Q

the most rapid fixative

A

Carnoy’s fluid

100
Q

an alcohol fixative that produces better reaction in Feulgen stain

A

Newcomer’s fluid

101
Q

fixative recommended for fixing mucopolysaccharides

A

Newcomer’s fluid

102
Q

this fixative conjugate fats and lipids permanently by making them insoluble to alcohol and xylene during dehydration and clearing

A

6% osmium tetroxide

103
Q

this fixative has a softening effect on dense fibrous tissues and precipitates proteins

A

trichloroacetic acid

104
Q

a fixative used at ice cold temperature (-5 to 4C) that is recommended for the study of water diffusible enzymes such as phosphatases and lipases

A

acetone

105
Q

used in fixing brain tissues for diagnosis of rabies

A

acetone
carnoy’s

106
Q

employed fixation technique for frozen tissue sections and bacteriologic smears

A

heat

MT6321 (9 decks)

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