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HISTOPATHOLOGY > CHAPTER 7 CHEMICAL FIXATIVES > Flashcards

CHAPTER 7 CHEMICAL FIXATIVES Flashcards

1
Q

(e.g., Aldehydes)

A

Crosslinking Fixatives

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2
Q

act by creating covalent chemical bonds between proteins in tissue.

A

Crosslinking Fixatives

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3
Q

This anchors soluble proteins to the cytoskeleton, and lends additional rigidity to the tissue.

A

Crosslinking Fixatives

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4
Q

(e.g., alcoholic fixatives)

A

Precipitating (or denaturing) fixatives

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5
Q

act by reducing the solubility of protein molecules and (often) by disrupting the hydrophobic interactions that give many proteins their tertiary structure.

A

Precipitating (or denaturing) fixatives

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6
Q

The precipitation and aggregation of proteins is a very different process from the crosslinking that occurs with the aldehyde fixatives.

A

Precipitating (or denaturing) fixatives

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7
Q
A

formaldehyde

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8
Q

most commonly used fixative in histology

A

formaldehyde

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9
Q

fixes the tissues by forming cross-linkages in the proteins, particularly between lysine residues; good for immunohistochemical techniques

A

formaldehyde

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10
Q

The standard solution is [?] neutral buffered formalin or approximately [?] formaldehyde in phosphate- buffered saline.

A

10%

3.7%-4.0%

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11
Q

is a gas produced by the oxidation of methyl alcohol, and is soluble in water to the extent of 37-40% weight in volume.

A

Formaldehyde

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12
Q

Pure stock solution of [?] is unsatisfactory for routine fixation since high concentrations of formaldehyde tend to over-harden the outer layer of the tissue and affect staining adversely.

A

40% formalin

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13
Q

is made with formaldehyde but the percentage denotes a different formaldehyde concentration.

A

Formalin

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14
Q

The most widely used fixative for routine histology is [?]

A

10% neutral buffered formalin (NBF, approximately 4% formaldehyde), buffered to pH 7 with phosphate buffer.

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15
Q

This fixative can effectively prevent autolysis and provide excellent preservation of tissue and cellular morphology.

A

10% neutral buffered formalin (NBF, approximately 4% formaldehyde)

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16
Q

It is considered the fixative of choice for many other procedures that require paraffin embedding, including immunohistochemistry and interphase Fluorescent In-Situ Hybridization (FISH).

A

10% neutral buffered formalin (NBF, approximately 4% formaldehyde)

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17
Q

FORMULA:
40% formaldehyde: 100 ml
Distilled water: 900 ml
Sodium dihydrogen phosphate monohydrate: 4 gm
Disodium hydrogen phosphate anhydrous 6.5 gm

A

10% Formal-Saline

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18
Q

The solution should have a pH of 6.8

A

10% Formal-Saline

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19
Q

Fixation time: 12 – 24 hours

A

10% Formal-Saline

Alcoholic formalin

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20
Q
  1. It penetrates and fixes tissues evenly.
A

10% Formal-Saline

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21
Q
  1. It preserves microanatomic and cytologic details with minimum shrinkage and distortion.
A

10% Formal-Saline

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22
Q
  1. Large specimens may be fixed for a long time provided that the solution is changed every three months.
A

10% Formal-Saline

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23
Q
  1. It preserves enzymes and nucleoproteins.
A

10% Formal-Saline

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24
Q
  1. It demonstrates fats and mucin.
A

10% Formal-Saline

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25
Q
  1. It does not over-harden tissues, thereby facilitating dissection of the specimen.
A

10% Formal-Saline

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26
Q
  1. It is ideal for most staining techniques, including silver
    impregnation.
A

10% Formal-Saline

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27
Q
  1. It allows natural tissue color to be restored upon immersion in 70% alcohol.
A

10% Formal-Saline

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28
Q
  1. It is a slow fixative. The period of fixation is required to be 24 hours or longer.
A

10% Formal-Saline

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29
Q

fixed tissues tend to shrink during alcohol dehydration; this may be reduced by secondary fixation.

A

10% Formal-Saline

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30
Q
  1. Metachromatic reaction of amyloid is reduced.
A

10% Formal-Saline

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31
Q
  1. Acid dye stains less brightly than when fixed with mercuric chloride.
A

10% Formal-Saline

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32
Q
  1. It is cheap, readily available, easy to prepare, and relatively stable, especially if stored in buffered solution.
A

Formalin

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33
Q
  1. It is compatible with many stains, and therefore can be used with various staining techniques depending upon the need of the tissues.
A

Formalin

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34
Q
  1. It does not over-harden tissues, even with prolonged periods of fixation, as long as solutions are regularly changed.
A

Formalin

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35
Q
  1. It penetrates tissues well.
A

Formalin

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36
Q
  1. It preserves fat and mucin, making them resistant to subsequent treatment with fat solvents, and allowing them to be stained for demonstration.
A

Formalin

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37
Q
  1. It preserves glycogen.
A

Formalin

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38
Q
  1. It preserves but does not precipitate proteins, thereby allowing tissue enzymes to be studied. It does not make tissues brittle, and is therefore recommended for nervous tissue preservation.
A

Formalin

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39
Q
  1. It allows natural tissue colors to be restored after fixation by immersing formalin-fixed tissues in 70% alcohol for one hour, and is therefore recommended for colored tissue photography.
A

Formalin

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40
Q
  1. It allows frozen tissue sections to be prepared easily.
A

Formalin

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41
Q
  1. It does not require washing out, unless tissues have stayed in formalin for excessively long periods of time.
A

Formalin

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42
Q
  1. Fumes are irritating to the nose and eyes and may cause sinusitis, allergic rhinitis, or excessive lacrimation.
A

Formalin

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43
Q
  1. The solution is irritating to the skin and may cause allergic dermatitis on prolonged contact.
A

Formalin

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44
Q
  1. It may produce considerable shrinkage of tissues.
A

Formalin

Carnoy’s Fixative

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45
Q
  1. It is a soft fixative and does not harden some cytoplasmic structures adequately enough for paraffin embedding.
A

Formalin

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46
Q

Reduces both basophilic and eosinophilic staining of cells, thereby reducing the quality of routine cytologic staining.

A

Formalin

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47
Q

Acidity of formic acid may, however, be used to an advantage when applying the silver impregnation technique of staining.

A

Formalin

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48
Q

It forms abundant brown pigment granules on blood-containing tissues, e.g., spleen, due to blackening of hemoglobin.

A

Formalin

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49
Q

Prolonged fixation may produce:
a. Bleaching of the specimen and loss of natural tissue colors.
b. Dispersal of fat from the tissue into the fluid.
c. Dissolution or loss of glycogen, and urate crystals

A

Formalin

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50
Q

solutions were devised as alternatives to mercuric chloride
formulations.

A

Zinc formalin (unbuffered)

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51
Q

FORMULA: Sat. Aq. Mercuric chloride 90 ml. Formaldehyde 40% 10 ml.

A

Formol-Corrosive (Formol-Sublimate)

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52
Q

Fixation time: 3-24 hours

A

Formol-Corrosive (Formol-Sublimate)

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53
Q

is recommended for routine post-mortem tissues.

A

Formol-mercuric chloride solution

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54
Q
  1. It penetrates small pieces of tissues rapidly.
A

Formol-Corrosive (Formol-Sublimate)

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55
Q
  1. It produces minimum shrinkage and hardening.
A

Formol-Corrosive (Formol-Sublimate)

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56
Q
  1. It is excellent for many staining procedures including silver reticulum methods.
A

Formol-Corrosive (Formol-Sublimate)

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57
Q
  1. It brightens cytoplasmic and metachromatic stains better than with formalin alone.
A

Formol-Corrosive (Formol-Sublimate)

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58
Q
  1. Cytological structures and blood cells are well preserved.
A

Formol-Corrosive (Formol-Sublimate)

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59
Q
  1. It fixes lipids, especially neutral fats and phospholipids.
A

Formol-Corrosive (Formol-Sublimate)

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60
Q
  1. Penetration is slow; hence, tissue sections should not be more than 1 cm thick.
A

Formol-Corrosive (Formol-Sublimate)

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61
Q
  1. It forms mercuric chloride deposits.
A

Formol-Corrosive (Formol-Sublimate)

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62
Q
  1. It does not allow frozen tissue sections to be made.
A

Formol-Corrosive (Formol-Sublimate)

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63
Q
  1. It inhibits the determination of the extent of tissue decalcification.
A

Formol-Corrosive (Formol-Sublimate)

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64
Q

is a polymerized form of formaldehyde, usually obtained as a fine white powder, which depolymerizes back to formalin when heated.

A

Paraformaldehyde

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65
Q

It is suitable for paraffin embedding and sectioning, and also for immunocytochemical analysis.

A

Paraformaldehyde

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66
Q

fixed samples can also be stained for general histology but the degree of fixation is less vigorous than Bouin’s so the quality of the morphology obtained will be less.

A

Paraformaldehyde

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67
Q

This fixative allows for subsequent immuno-detection of certain antigens and should therefore be used when the objective is to study morphology and protein expression simultaneously.

A

Paraformaldehyde

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68
Q

Its effects are reversible by excess water and it avoids formalin pigmentation.

A

Paraformaldehyde

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69
Q

Other benefits include: Long term storage and good tissue penetration.

A

Paraformaldehyde

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70
Q

is a mixture of paraformaldehyde and glutaral-dehyde.

A

Karnovsky’s Fixative (4% Paraformaldehyde-1% Glutaraldehyde in 0.1M Phosphate Buffer)

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71
Q

It is suitable for use when preparing samples for light microscopy in resin embedding and sectioning, and for electron microscopy.

A

Karnovsky’s Fixative (4% Paraformaldehyde-1% Glutaraldehyde in 0.1M Phosphate Buffer)

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72
Q

This fixative should always be prepared fresh.

A

Karnovsky’s Fixative (4% Paraformaldehyde-1% Glutaraldehyde in 0.1M Phosphate Buffer)

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73
Q
  1. It has a more stable effect on tissues, giving a firmer texture with better tissue sections, especially of central nervous tissues.
A

Glutaraldehyde

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74
Q
  1. It preserves plasma proteins better.
A

Glutaraldehyde

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75
Q
  1. It produces less tissue shrinkage.
A

Glutaraldehyde

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76
Q
  1. It preserves cellular structures better; hence, is recommended for electron microscopy.
A

Glutaraldehyde

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77
Q
  1. It is more pleasant and less irritating to the nose.
A

Glutaraldehyde

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78
Q
  1. It does not cause dermatitis.
A

Glutaraldehyde

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79
Q
  1. It is more expensive.
A

Glutaraldehyde

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80
Q
  1. It is less stable.
A

Glutaraldehyde

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81
Q
  1. It penetrates tissues more slowly.
A

Glutaraldehyde

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82
Q
  1. It tends to make tissue (i.e. renal biopsy) more brittle.
A

Glutaraldehyde

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83
Q
  1. It reduces PAS positivity of reactive mucin.
A

Glutaraldehyde

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84
Q

This may be prevented by immersing glutaraldehyde-fixed tissues in a mixture of

A

concentrated glacial acetic acid and aniline oil.

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85
Q
  1. The specimen vial must be kept refrigerated during the fixation process.
A

Glutaraldehyde

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86
Q
  1. Solution may be changed several times during fixation by swirling the vials to make sure that the specimen is in contact with fresh solution all the time.
A

Glutaraldehyde

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87
Q
  1. It is excellent for fixing dry and wet smears, blood smears and bone marrow tissues.
A

Methyl Alcohol 100%

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88
Q
  1. It fixes and dehydrates at the same time.
A

Methyl Alcohol 100%

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89
Q
  1. Penetration is slow.
A

Methyl Alcohol 100%

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90
Q
  1. If left in fixative for more than 48 hours, t issues may be over hardened and difficult to cut.
A

Methyl Alcohol 100%

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91
Q
  • is used for fixing touch preparations , although some touch preparations are air dried and not fixed, for certain special staining procedures such as Wright-Giemsa.
A

Isopropyl Alcohol 95%

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92
Q

is used at concentrations of 70-100%. If the lower concentrations are used, the RBC’s become hemolyzed and WBC’s are inadequately preserved.

A

Ethyl Alcohol

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93
Q

It may be used as a simple fixative.

A

Ethyl Alcohol

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94
Q

It is, however, more frequently incorporated into compound fixatives for better results.

A

Ethyl Alcohol

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95
Q

Fixation Time: 18-24 hours

A

Ethyl Alcohol

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96
Q
  1. It preserves but does not fix glycogen.
A

Ethyl Alcohol

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97
Q
  1. It fixes blood, tissue films and smears.
A

Ethyl Alcohol

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98
Q
  1. It preserves nucleoproteins and nucleic acids, hence, is used for histochemistry, especially for enzyme studies.
A

Ethyl Alcohol

Carnoy’s Fixative

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99
Q
  1. It fixes tissue pigments fairly well.
A

Ethyl Alcohol

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100
Q
  1. It is ideal for small tissue fragments.
A

Ethyl Alcohol

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101
Q
  1. Hemosiderin preservation is less than in buffered formaldehyde.
A

Ethyl Alcohol

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102
Q
  1. It is a strong reducing agent; hence, should not be mixed with chromic acid, potassium dichromate and osmium tetroxide which are strong oxidizing agents.
A

Ethyl Alcohol

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103
Q
  1. Lower concentrations (70-80%) will cause RBC hemolysis and inadequately preserve leukocytes.
A

Ethyl Alcohol

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104
Q
  1. It dissolves fats and lipids, as a general rule. Alcohol-containing fixatives are contraindicated when lipids are to be studied.
A

Ethyl Alcohol

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105
Q
  1. It causes glycogen granules to move towards the poles or ends of the cells (polarization).
A

Ethyl Alcohol

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106
Q
  1. Tissue left in alcohol too long will shrink, making it difficult or impossible to cut.
A

Ethyl Alcohol

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107
Q
  1. It causes polarization of glycogen granules.
A

Ethyl Alcohol

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108
Q
  1. It produces considerable hardening and shrinkage of tissues.
A

Ethyl Alcohol

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109
Q

FORMULA:
Absolute alcohol 60 ml.
Chloroform 30 ml.
Glacial acetic acid 10 ml.

A

Carnoy’s Fixative

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110
Q

Fixation Time: 1-3 hours

A

Carnoy’s Fixative

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111
Q

It is considered to be the most rapid fixative and may be used for urgent biopsy specimens for paraffin processing within 5 hours.

A

Carnoy’s Fixative

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112
Q

It fixes and dehydrates at the same time.

A

Carnoy’s Fixative

Methyl Alcohol 100%

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113
Q
  1. It permits good nuclear staining and differentiation.
A

Carnoy’s Fixative

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114
Q
  1. It preserves Nissl granules and cytoplasmic granules well.
A

Carnoy’s Fixative

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115
Q
  1. It preserves nucleoproteins and nucleic acids.
A

Carnoy’s Fixative

Methyl Alcohol 100%

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116
Q
  1. It is an excellent fixative for glycogen since aqueous solutions are avoided.
A

Carnoy’s Fixative

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117
Q
  1. It is very suitable for small tissue fragments such as curettings and biopsy materials.
A

Carnoy’s Fixative

Ideal: Ethyl Alcohol

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118
Q
  1. Following fixation for one hour, tissues may be transferred directly to absolute alcohol-chloroform mixture, thereby shortening processing time.
A

Carnoy’s Fixative

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119
Q
  1. It is also used to fix brain tissue for the diagnosis of rabies.
A

Carnoy’s Fixative

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120
Q
  1. It produces RBC hemolysis, dissolves lipids and can produce excessive hardening and shrinkage.
A

Carnoy’s Fixative; Isopropyl Alcohol 95%

considerable: Ethyl Alcohol

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121
Q
  1. It causes considerable tissue shrinkage.
A

Carnoy’s Fixative

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122
Q
  1. It is suitable only for small pieces of tissues due to slow penetration.
A

Carnoy’s Fixative

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123
Q
  1. It tends to harden tissues excessively and distorts tissue morphology.
A

Carnoy’s Fixative

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124
Q
  1. It dissolves fat, lipids, and myelin.
A

Carnoy’s Fixative : myelin

Ethyl Alcohol

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125
Q
  1. It leads to polarization unless very cold temperatures (-70°C) are used.
A

Carnoy’s Fixative

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126
Q
  1. It dissolves acid-soluble cell granules and pigments.
A

Carnoy’s Fixative

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127
Q

Fixation time: 3 - 4 hours

A

Clarke’s solution

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128
Q

Fixation time: 12 – 24 hours

A

Alcoholic formalin

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129
Q

This is a simple microanatomical fixative made up of saturated
formaldehyde (40%, by weight volume) diluted to 10% with sodium chloride.

A

10% Formal-Saline

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130
Q

This mixture of formaldehyde in isotonic saline was widely used for routine histopathology prior to the introduction of phosphate buffered formalin.

A

10% Formal-Saline

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131
Q

It is recommended for fixation of central nervous tissues and general post-mortem tissues for histochemical examination.

A

10% Formal-Saline

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132
Q

It is also recommended for the preservation of lipids, especially phospholipids.

A

10% Formal-Saline

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133
Q

The buffer tends to prevent the formation of formalin pigment.

A

10% Formal-Saline

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134
Q

Many epitopes require antigen retrieval for successful immunohistochemical (IHC) staining procedure following its use.

A

10% Formal-Saline

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135
Q

Most pathologists feel comfortable interpreting the morphology produced with this type of fixative.

A

10% Formal-Saline

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136
Q

It often produces formalin pigment.

A

10% Formal-Saline

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137
Q

solutions were devised as alternatives to mercuric chloride formulations.

A

Zinc formalin

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138
Q

They are said to give improved results with immunohistochemistry.

A

Zinc formalin (unbuffered)

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139
Q

There are a number of alternative formulas available some of which contain zinc chloride which is thought to be slightly more corrosive than zinc sulphate.

A

Zinc formalin (unbuffered)

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140
Q

has been used on frozen sections and smears.

A

Clarke’s solution

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141
Q

It can produce fair results after conventional processing if fixation time is kept very short.

A

Clarke’s solution

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142
Q

It preserves nucleic acids but extracts lipids.

A

Clarke’s solution

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143
Q

Tissues can be transferred directly into 95% ethanol.

A

Clarke’s solution

primary fixation specimens: Alcoholic formalin, Formol-acetic alcohol

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144
Q

combines a denaturing fixative with the additive and cross-linking effects of formalin.

A

Alcoholic formalin

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145
Q

It is sometimes used during processing to complete fixation following incomplete primary formalin fixation.

A

Alcoholic formalin

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146
Q

It can be used for fixation or post-fixation of large fatty specimens (particularly breast), because it will allow lymph nodes to be more easily detected as it clears and extracts lipids.

A

Alcoholic formalin

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147
Q

If used for primary fixation specimens, it can be placed directly into 95% ethanol for processing.

A

Alcoholic formalin

Formol-acetic alcohol

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148
Q

Fixation time: 1 - 6 hours

A

Formol-acetic alcohol

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149
Q

alcohol is a faster acting agent than alcoholic formalin due to the presence of acetic acid that can also produce formalin pigment.

A

Formol-acetic alcohol

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150
Q

It is sometimes used to fix diagnostic cryostat sections.

A

Formol-acetic alcohol

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151
Q

If used for primary fixation, the specimens can be placed directly into 95% ethanol for processing.

A

Alcoholic formalin

Formol-acetic alcohol

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152
Q

Post-fixation with phenol-formalin for 6 hours or more can enhance immunoperoxidase studies on the tissues, and in some cases, electron microscopy, if it is necessary at a later time to establish a diagnosis.

A

Gendre’s Fixative

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153
Q
  1. Fixation is faster (fixation time is reduced to one-half).
A

Gendre’s Fixative

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154
Q
  1. It can be used for rapid diagnosis because it fixes and dehydrates at the same time, e.g., in the frozen section room.
A

Gendre’s Fixative

Methyl Alcohol 100% ; Carnoy’s Fixative

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155
Q
  1. It is good for preservation of glycogen and for micro-incineration technique (the burning of a minute tissue specimen for identification of mineral elements from the ashes).
A

Gendre’s Fixative

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156
Q
  1. It is used to fix sputum, since it coagulates mucus.
A

Gendre’s Fixative

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157
Q
  1. It produces gross hardening of tissues.
A

Gendre’s Fixative

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158
Q
  1. It causes partial lysis of RBC.
A

Gendre’s Fixative

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159
Q
  1. Preservation of iron-containing pigments is poor.
A

Gendre’s Fixative

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160
Q
  1. Formaldehyde does not give as good a morphological picture as glutaraldehyde.
A

Gendre’s Fixative

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161
Q
  1. Formaldehyde causes little cross-linking under usual fixation conditions where low concentrations of proteins are used, while glutaraldehyde is most effective at cross-linking.
A

Gendre’s Fixative

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162
Q

Fixation time: 12-18 hours at 3°C

A

Newcomer’s Fluid

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163
Q
  1. It is recommended for fixing mucopolysaccharides and nuclear proteins.
A

Newcomer’s Fluid

164
Q
  1. It produces better reaction in Feulgen stain than Carnoy’s fluid.
A

Newcomer’s Fluid

165
Q
  1. It acts both as a nuclear and histochemical fixative.
A

Newcomer’s Fluid

166
Q

PRECIPITATING (ALCOHOLIC) FIXATIVES:

A
167
Q

METALLIC FIXATIVES:

A
168
Q

OXIDIZING AGENTS:

A
169
Q

CHROMATE FIXATIVES:

A
170
Q

PICRIC ACID FIXATIVES:

A
171
Q
  1. It penetrates and hardens tissues rapidly and well.
A

Mercuric Chloride

172
Q
  1. Nuclear components are shown in fine detail.
A

Mercuric Chloride

173
Q
  1. It precipitates all proteins.
A

Mercuric Chloride

174
Q
  1. It has a greater affinity to acid dyes and is preferred in lieu of formaldehyde for cytoplasmic staining.
A

Mercuric Chloride

175
Q
  1. Trichrome staining is excellent.
A

Mercuric Chloride

176
Q
  1. It is the routine fixative of choice for preservation of cell detail in tissue photography.
A

Mercuric Chloride

177
Q
  1. It permits brilliant metachromatic staining of cells.
A

Mercuric Chloride

178
Q
  1. It is recommended for renal tissue, fibrin, connective tissue and muscle.
A

Mercuric Chloride

179
Q
  1. It causes marked shrinkage of cells (this may be counteracted by addition of acid).
A

Mercuric Chloride

180
Q
  1. It rapidly hardens the outer layer of the tissue with incomplete fixation of the center; therefore, thin sections should be made.
A

Mercuric Chloride

181
Q
  1. Penetration beyond the first 2-3 millimeters is slow; hence, not more than 5 mm. thickness of tissues should be used.
A

Mercuric Chloride

182
Q
  1. If left in fixative for more than 1-2 days, the tissue becomes unduly hard and brittle.
A

Mercuric Chloride

183
Q
  1. It prevents adequate freezing of fatty tissues and makes cutting of frozen tissues difficult.
A

Mercuric Chloride

184
Q
  1. It causes considerable lysis of red blood cells and removes much iron from hemosiderin.
A

considerable: Mercuric Chloride

Zenker’s Solution

185
Q
  1. It is inert to fats and lipids.
A

Mercuric Chloride

186
Q
  1. It leads to the formation of black granular deposits in the tissues.
A

Mercuric Chloride

187
Q

.It reduces the amount of demonstrable glycogen.

A

Mercuric Chloride

188
Q
  1. Compound solutions deteriorate rapidly upon addition of glacial acetic acid to formalin.
A

Mercuric Chloride

189
Q
  1. It is extremely corrosive to metals.
A

Mercuric Chloride

190
Q
  1. Sections must be cleared of mercury deposits before immunostaining.
    Black deposits may be removed by adding saturated iodine solution in 95% alcohol, the iodine being decolorized with absolute alcohol in the subsequent stages of dehydration.
A

Mercuric Chloride

191
Q
  1. Compound solutions must always be freshly prepared.
A

Mercuric Chloride

192
Q
  1. The use of metallic forceps and of metal caps to cover the bottles containing the fixative should be avoided.
A

Mercuric Chloride

193
Q
  1. Contact with personal jewelries should be avoided.
A

Mercuric Chloride

194
Q
  1. Mercury-containing solutions (Zenker’s or B-5) should always be discarded into proper containers. Mercury, if poured down a drain, will form amalgams with the metal that build up and cannot be removed.
A

Mercuric Chloride

195
Q

Fixation time: 12-24 hours

A

Zenker’s Solution

10% Formal-Saline

Alcoholic Formalin

196
Q
  1. It produces a fairly rapid and even fixation of tissues.
A

Zenker’s Solution

197
Q
  1. Stock solutions keep well without disintegration.
A

Zenker’s Solution

198
Q
  1. It is recommended for trichrome staining.
A

Zenker’s Solution

199
Q
  1. It permits brilliant staining of nuclear and connective tissue fibers.
A

Zenker’s Solution

200
Q
  1. It is recommended for congested specimens (such as lung, heart and blood vessels) and gives good results with PTAH and trichrome staining.
A

Zenker’s Solution

201
Q
  1. It is compatible with most stains.
A

Zenker’s Solution

202
Q
  1. It may act as a mordant to make certain special staining reactions possible.
A

Zenker’s Solution

203
Q
  1. It is a stable fixative that can be stored for many years.
A

Zenker’s Solution

204
Q
  1. Penetration is poor.
A

Zenker’s Solution

205
Q
  1. It is not stable after addition of acetic acid.
A

Zenker’s Solution

206
Q
  1. Prolonged fixation (for more than 24 hours) will make tissues brittle and hard.
A

Zenker’s Solution

207
Q
  1. It causes lysis of red blood cells and removes iron from hemosiderin.
A

Zenker’s Solution

208
Q
  1. It does not permit cutting of frozen sections.
A

Zenker’s Solution

209
Q
  1. It has the tendency to form mercuric pigment deposits or precipitates.
A

Zenker’s Solution

210
Q
  1. Tissue must be washed in running water for several hours (or overnight) before processing. Insufficient washing may inhibit or interfere with good cellular staining.
A

Zenker’s Solution

211
Q
  1. Do not let tissues stay in solution for more than 24 hours.
A

Zenker’s Solution

212
Q
  1. Solutions must always be freshly prepared.
A

Zenker’s Solution

213
Q
  1. Tissues should be cut thin (2-3 mm.) and hollow organs should be opened to promote complete penetration and fixation.
A

Zenker’s Solution

214
Q
  1. Tissues must be washed out thoroughly in running water to permit good staining.
A

Zenker’s Solution

215
Q
  1. It produces mercury pigment which should be removed from sections prior to staining and can produce chrome pigment if tissue is not washed
    in water prior to processing. After water washing, tissue should be stored in 70% ethanol.
A

Zenker’s Solution

216
Q
  1. Mercuric deposits may be removed by immersing tissues in alcoholic iodine solution prior to staining, through a process known as de- zenkerization.
A

Zenker’s Solution

217
Q

Fixation time: 4 – 24 hours

A

Zenker-Formol (Helly’s) Solution

218
Q

is an excellent fixative for bone marrow, extramedullary hematopoiesis and intercalated discs of cardiac muscle.

A

Zenker-Formol (Helly’s) Solution

219
Q

However, it produces mercury pigment which should be removed from sections prior to staining and it can produce chrome pigment if tissue is not washed in water prior to processing.

A

Zenker-Formol (Helly’s) Solution

220
Q

After water washing, fixed tissue should be stored in 70% ethanol.

A

Zenker-Formol (Helly’s) Solution

221
Q

Because of the low pH of this fixative, formalin pigment may also occur.

A

Zenker-Formol (Helly’s) Solution

222
Q

Never use metal forceps to handle tissue.

A

Zenker-Formol (Helly’s) Solution

223
Q
  1. It is an excellent microanatomic fixative for pituitary gland, bone marrow and blood containing organs such as spleen and liver.
A

Zenker-Formol (Helly’s) Solution

224
Q
  1. It penetrates and fixes tissues well.
A

Zenker-Formol (Helly’s) Solution

225
Q
  1. Nuclear fixation and staining is better than with Zenker’s.
A

Zenker-Formol (Helly’s) Solution

226
Q
  1. It preserves cytoplasmic granules well.
A

Zenker-Formol (Helly’s) Solution

227
Q

brown pigments are produced if tissues (especially blood​ containing organs) are allowed to stay in the fixative for more than 24 hours due to RBC lysis. This may be removed by immersing the tissue in saturated alcoholic picric acid or sodium hydroxide.

A

Zenker-Formol (Helly’s) Solution

228
Q

Fixation time: 4 – 8 hours

A

Lillie’s B-5 Fixative

229
Q
  1. Despite its mercuric chloride content and consequent problems with disposal, this solution is popular for fixation of hematopoietic, bone marrow biopsies and lymphoid tissue.
A

Lillie’s B-5 Fixative

230
Q
  1. Rapid fixation can be achieved in 1 1/2 - 2 hours.
A

Lillie’s B-5 Fixative

231
Q
  1. It produces excellent nuclear detail, provides good results with many special stains, and is recommended for immunohisto-chemical staining.
A

Lillie’s B-5 Fixative

232
Q
  1. Sections will require the removal of mercury pigment prior to staining.
A

Lillie’s B-5 Fixative

233
Q
  1. Tissue should not be stored in this fixative but placed in 70% ethanol instead.
A

Lillie’s B-5 Fixative

234
Q
  1. Over-fixation hardens the tissue and makes cutting difficult.
A

Lillie’s B-5 Fixative

235
Q
  1. The two working solutions are kept separate, since the mixture is unstable. Mix just prior to use.
A

Lillie’s B-5 Fixative

236
Q
  1. Some will form precipitate on standing, but this is of no consequence.
A

Lillie’s B-5 Fixative

237
Q
  1. As with all mercuric chloride fixatives, the mercury pigment can be removed by de-zenkerization.
A

Lillie’s B-5 Fixative

238
Q

Fixation time: 3-12 hours

A

Heidenhain’s Susa Solution

239
Q
  1. It penetrates and fixes tissues rapidly and evenly.
A

Heidenhain’s Susa Solution

240
Q
  1. It produces minimum shrinkage and hardening of tissues due to the counter-balance of the swelling effects of acids and the shrinkage effect of mercury.
A

Heidenhain’s Susa Solution

241
Q
  1. It permits most staining procedures to be done, including silver impregnation, producing brilliant results with sharp nuclear and cytoplasmic details.
A

Heidenhain’s Susa Solution

242
Q
  1. It permits easier sectioning of large blocks of fibrous connective tissues.
A

Heidenhain’s Susa Solution

243
Q
  1. may be transferred directly to 95% alcohol or absolute alcohol, thereby reducing processing time.
A

Heidenhain’s Susa Solution

244
Q

is recommended mainly for tumor biopsies especially of the skin; it is an excellent cytologic fixative.

A

Heidenhain’s Susa Solution

245
Q
  1. Prolonged fixation of thick materials may produce considerable shrinkage, hardening and bleaching; hence, tissues should not be more than 1 cm. thick.
A

Heidenhain’s Susa Solution

246
Q
  1. RBC preservation is poor.
A

Heidenhain’s Susa Solution

247
Q
  1. Some cytoplasmic granules are dissolved.
A

Heidenhain’s Susa Solution

248
Q
  1. Mercuric chloride deposits tend to form on tissues; these may be removed by immersion of tissues in alcoholic iodine solution.
A

Heidenhain’s Susa Solution

249
Q
  1. Weigert’s method of staining elastic fibers is not possible
A

Heidenhain’s Susa Solution

250
Q

After using, the tissue should be transferred directly to a high-grade alcohol, e.g. 96% or absolute alcohol, to avoid undue swelling of tissues caused by treatment with low-grade alcohol or water.

A

Heidenhain’s Susa Solution

251
Q

It fixes conjugated fats and lipids permanently by making them insoluble during subsequent treatment with alcohol and xylene.

Fats form hydrated (?), are stained black and therefore are easier to identify.

A

Osmium Tetroxide (Osmic Acid; OsO4)

252
Q
  1. It preserves cytoplasmic structures well, e.g. Golgi bodies and mitochondria.
A

Osmium Tetroxide (Osmic Acid; OsO4)

253
Q
  1. It fixes myelin and peripheral nerves well, hence, it is used extensively for neurological tissues.
A

Osmium Tetroxide (Osmic Acid; OsO4)

254
Q
  1. It produces brilliant nuclear staining with safranin.
A

Osmium Tetroxide (Osmic Acid; OsO4)

255
Q
  1. It adequately fixes materials for ultrathin sectioning in electron microscopy, since it rapidly fixes small pieces of tissues and aids in their staining.
A

Osmium Tetroxide (Osmic Acid; OsO4)

256
Q
  1. It precipitates and gels proteins.
A

Osmium Tetroxide (Osmic Acid; OsO4)

257
Q
  1. It shows uniformly granular nuclei with clear cytoplasmic background.
A

Osmium Tetroxide (Osmic Acid; OsO4)

258
Q
  1. Some tissues (e.g. adrenal glands) are better fixed in vapor form. This eliminates “washing out” of the fixed tissues.
A

Osmium Tetroxide (Osmic Acid; OsO4)

259
Q

completely permeabilizes cell membranes. The osmolarity of the fixative vehicle or solute is relatively unimportant.

A

Osmium Tetroxide (Osmic Acid; OsO4)

260
Q
  1. It penetrates tissue blocks in a gradient and in large samples the center of the block may not be as well fixed as the peripheral areas.
A

Osmium Tetroxide (Osmic Acid; OsO4)

261
Q
  1. Over-fixation may result in extraction of cell components during dehydration and increases the hardness and brittleness of the tissue (for most tissues, 1mm blocks, should not be exposed to osmium for less than 0.5 or more than 1.5 hours).
A

Osmium Tetroxide (Osmic Acid; OsO4)

262
Q
  1. It is very expensive.
A

Osmium Tetroxide (Osmic Acid; OsO4)

263
Q
  1. It is a poor penetrating agent, suitable only for small pieces of tissues (2-3 mm. thick).
A

Osmium Tetroxide (Osmic Acid; OsO4)

264
Q
  1. It is readily reduced by contact with organic matter and exposure to sunlight, forming a black precipitate which settles at the bottom of the container.
A

Osmium Tetroxide (Osmic Acid; OsO4)

265
Q
  1. Prolonged exposure to acid vapor can irritate the eye, producing conjunctivitis, or cause the deposition of black osmic oxide in the cornea, producing blindness.
A

Osmium Tetroxide (Osmic Acid; OsO4)

266
Q
  1. It inhibits hematoxylin and makes counterstaining difficult.
A

Osmium Tetroxide (Osmic Acid; OsO4)

267
Q
  1. It is extremely volatile.
A

Osmium Tetroxide (Osmic Acid; OsO4)

268
Q

I. Eyes and skin may be protected by working in a fume hood or wearing protective plastic masks or gloves while using

A

Osmium Tetroxide (Osmic Acid; OsO4)

269
Q
  1. It should be kept in a dark-colored, chemically clean bottle to prevent evaporation and reduction by sunlight or organic matter.
A

Osmium Tetroxide (Osmic Acid; OsO4)

270
Q
  1. It should be kept in a cool place or refrigerated to prevent deterioration.
A

Osmium Tetroxide (Osmic Acid; OsO4)

271
Q
  1. Addition of saturated aqueous mercuric chloride solution (0.5 to 1 ml/100 ml of stock solution) will prevent its reduction with formation of black deposits.
A

Osmium Tetroxide (Osmic Acid; OsO4)

272
Q
  1. Black (?) crystals may be dissolved in cold water.
A

Osmium Tetroxide (Osmic Acid; OsO4)

273
Q
  1. To prevent contact of tissues with black precipitate formed in the bottom of the jar, the tissues may be wrapped in cotton gauze and suspended in the fluid by means of a thread.
A

Osmium Tetroxide (Osmic Acid; OsO4)

274
Q
  1. (?)-fixed tissues must be washed in running water for at least 24 hours to prevent formation of artefacts.
A

Osmium Tetroxide (Osmic Acid; OsO4)

275
Q

is the most common chrome-osmium acetic acid fixative used, recommended for nuclear preparation of such sections.

A

Flemming’s Solution

276
Q

Fixation time: 24 - 48 bouts

A

Flemming’s Solution

277
Q
  1. It is an excellent fixative for nuclear structures, e.g. chromosomes.
A

Flemming’s Solution

278
Q
  1. It permanently fixes fat.
A

Flemming’s Solution

279
Q
  1. Relatively less amount of solution is required for fixation (less than 10 times the volume of the tissues to be fixed).
A

Flemming’s Solution

280
Q
  1. It is a poor penetrating agent; hence, is applicable only to small pieces of tissues.
A

Flemming’s Solution

281
Q
  1. The solution deteriorates rapidly and must be prepared immediately before use.
A

Flemming’s Solution

282
Q
  1. depress the staining power of hematoxylin (especially Ehrlich’s hematoxylin).
A

Flemming’s Solution

283
Q
  1. It has a tendency to form artifact pigments; these may be removed by washing the fixed tissue in running tap water for 24 hours before dehydration.
A

Flemming’s Solution

284
Q

5 It is very expensive.

A

Flemming’s Solution

285
Q
  • is made up only of chromic and osmic acid, recommended for cytoplasmic structures particularly the mitochondria.
A

Flemming’s solution without acetic acid

286
Q

The removal of acetic acid from the formula serves to improve the cytoplasmic detail of the cell.

A

Flemming’s solution without acetic acid

287
Q

Fixation time: 24 - 48 hours

A

Flemming’s solution without acetic acid

288
Q

Advantages and Disadvantages: same as Flemming’s solution.

A

Flemming’s solution without acetic acid

289
Q

is used in 1-2% aqueous solution, usually as a constituent of a compound fixative.

A

Chromic Acid

290
Q

It precipitates all proteins and adequately preserves carbohydrates.

A

Chromic Acid

291
Q

It is a strong oxidizing agent; hence, a strong reducing agent (e.g. formaldehyde) must be added to chrome-containing fixatives before use in order to prevent counteracting effects and consequent decomposition of solution upon prolonged standing.

A

Chromic Acid

292
Q

is used in a 3% aqueous solution.

A

Potassium Dichromate

293
Q

I. It fixes but does not precipitate cytoplasmic structures.

A

Potassium Dichromate

294
Q
  1. It preserves lipids.
A

Potassium Dichromate

295
Q
  1. It preserves mitochondria (If used in pH 4.5-5.2, mitochondria is fixed. If the solution becomes acidified, cytoplasm, chromatin bodies and chromosomes are fixed but mitochondria are destroyed).
A

Potassium Dichromate

296
Q

Fixation time: 12-48 hours

A

Regaud’s (Muller’s) Fluid

297
Q
  1. It penetrates tissues well.
A

Regaud’s (Muller’s) Fluid

298
Q
  1. It hardens tissues better and more rapidly than Orth’s fluid.
A

Regaud’s (Muller’s) Fluid

299
Q
  1. It is recommended for the demonstration of chromatin, mitochondria, mitotic figures, Golgi bodies, RBC and colloid-containing tissues.
A

Regaud’s (Muller’s) Fluid

300
Q
  1. It deteriorates and darkens on standing due to acidity; hence, the solution must always be freshly prepared.
A

Regaud’s (Muller’s) Fluid

301
Q
  1. Penetration is slow, hence, tissues should not be thicker than 2-3 mm.
A

Regaud’s (Muller’s) Fluid

302
Q
  1. Chromate-fixed tissues tend to produce precipitates of sub-oxide, hence should be thoroughly washed in running water prior to dehydration.
A

Regaud’s (Muller’s) Fluid

303
Q
  1. Prolonged fixation blackens tissue pigments, such as melanin; this may be removed by washing the tissues in running tap water prior to dehydration.
A

Regaud’s (Muller’s) Fluid

304
Q

5.Glycogen penetration is poor; it is therefore, generally contraindicated for carbohydrates.

A

Regaud’s (Muller’s) Fluid

305
Q
  1. Nuclear staining is poor.
A

Regaud’s (Muller’s) Fluid

306
Q
  1. It does not preserve fats.
A

Regaud’s (Muller’s) Fluid

307
Q
  1. It preserves hemosiderin less than buffered formalin.
A

Regaud’s (Muller’s) Fluid

308
Q
  1. Intensity of PAS reaction is reduced.
A

Regaud’s (Muller’s) Fluid

309
Q

Fixation time: 36-72 hours

A

Orth’s Fluid

310
Q
  1. It is recommended for study of early degenerative processes and tissue necrosis.
A

Orth’s Fluid

311
Q
  1. It demonstrates rickettsiae and other bacteria.
A

Orth’s Fluid

312
Q
  1. It preserves myelin better than buffered formalin.
A

Orth’s Fluid

313
Q

Disadvantages: Same as in Regaud’s fluid.

A

Orth’s Fluid

314
Q

The complementary effects of the three ingredients work well together to maintain morphology.

A

Bouin’s Solution

315
Q

Specimens are usually fixed for 24 hours.

A

Bouin’s Solution

316
Q

Prolonged storage in this acidic mixture causes hydrolysis and loss of stainable DNA and RNA.

A

Bouin’s Solution

317
Q

Thorough washing after fixation is necessary.

A

Bouin’s Solution

318
Q

is recommended for fixation of embryos and pituitary biopsies.

A

Bouin’s Solution

319
Q

It gives very good results with tissue that is subsequently stained with trichrome.

A

Bouin’s Solution

320
Q

It preserves glycogen well but usually lyses erythrocytes.

A

Bouin’s Solution

321
Q

It is sometimes recommended for gastro-intestinal tract biopsies, animal embryos and endocrine gland tissue.

A

Bouin’s Solution

322
Q

It stains tissue bright yellow due to picric acid.

A

Bouin’s Solution

323
Q

Excess picric should be washed from tissues prior to staining with 70% ethanol.

A

Bouin’s Solution

324
Q

Because of its acidic nature, it will slowly remove small calcium deposits and iron deposits.

A

Bouin’s Solution

325
Q
  1. It is an excellent fixative for glycogen demonstration.
A

Bouin’s Solution

326
Q
  1. It penetrates tissues well and fixes small tissues rapidly.
A

Bouin’s Solution

327
Q
  1. The yellow stain taken in by tissues prevents small fragments from being overlooked.
A

Bouin’s Solution

328
Q
  1. It allows brilliant staining with the trichrome method.
A

Bouin’s Solution

329
Q
  1. It is suitable for Aniline stains (Mallory’s, Heidenhain’s or Masson’s methods).
A

Bouin’s Solution

330
Q
  1. It precipitates all proteins.
A

Bouin’s Solution

331
Q
  1. It is stable.
A

Bouin’s Solution

332
Q
  1. It causes RBC hemolysis and reduces the amount of demonstrable ferric iron in tissue.
A

Bouin’s Solution

333
Q
  1. It is not suitable for frozen sections because it causes frozen sections to crumble when cut.
A

Bouin’s Solution

334
Q
  1. Prolonged fixation makes tissues hard, brittle and difficult to section. Tissues should not be allowed to remain in the fluid for more than 12-24 hours (depending on size).
A

Bouin’s Solution

335
Q
  1. Picrates form protein precipitates that are soluble in water; hence, tissues must be first rendered insoluble by direct immersion in 70% ethyl alcohol.
A

Bouin’s Solution

336
Q
  1. Picric acid fixed tissues must never be washed in water before dehydration.
A

Bouin’s Solution

337
Q
  1. Picric acid will produce excessive staining of tissues; to remove the yellow color, tissues may be placed in 70% ethyl alcohol followed by 5% sodium thiosulfate and then washed in running water.
A

Bouin’s Solution

338
Q
  1. Picric acid is highly explosive when dry, and therefore must be kept moist with distilled water or saturated alcohol at 0.5 to 1% concentration during storage.
A

Bouin’s Solution

339
Q
  1. It alters and dissolves lipids.
A

Bouin’s Solution

340
Q
  1. It interferes with Azure eosin method of staining; hence, tissues should be thoroughly washed with alcohol.
A

Bouin’s Solution

341
Q

It is recommended for gastro-intestinal tract specimens and fixation of endocrine tissues.

A

Hollande’s Solution

342
Q

It produces less lysis than Bouin’s Solution.

A

Hollande’s Solution

343
Q

It has some decalcifying properties.

A

Hollande’s Solution

344
Q

The fixative must be washed from tissues if they are to be put into phosphate buffered formalin on the processing machine because an insoluble phosphate precipitate will form.

A

Hollande’s Solution

345
Q

Fixation time: 4 – 18 hours

A

Bouin’s Solution

Hollande’s Solution

Gendre’s solution

346
Q

Store at room temperature

A

Bouin’s Solution

347
Q

This is an alcoholic Bouin’s solution that appears to improve upon ageing.

A

Gendre’s solution

348
Q

It is highly recommended for the preservation of glycogen and other carbohydrates.

A

Gendre’s solution

349
Q

After fixation the tissue is placed into 70% ethanol.

A

Gendre’s solution

350
Q

Residual yellow color should be washed out before staining.

A

Gendre’s solution

351
Q
  1. It produces minimal distortion of micro-anatomical structures and can be used for general and special stains. (The shrinking effect of picric acid is balanced by the swelling effect of glacial acetic acid.)
A

Gendre’s solution

352
Q
  1. It is an excellent fixative for preserving soft and delicate structures (e.g. endometrial curettings).
A

Gendre’s solution

353
Q
  1. It penetrates rapidly and evenly, and causes little shrinkage.
A

Gendre’s solution

354
Q
  1. Yellow stain is useful when handling fragmentary biopsies.
A

Gendre’s solution

355
Q
  1. It permits brilliant staining of tissues.
A

Gendre’s solution

356
Q
  1. It is the preferred fixative for tissues to be stained by Masson’s trichrome for collagen, elastic or connective tissue. (If tissue is fixed in formalin, a pre-treatment in Bouin’s solution (as mordant prior to trichrome stain) is recommended.
A

Gendre’s solution

357
Q
  1. It preserves glycogen.
A

Gendre’s solution

358
Q
  1. It does not need “washing out”.
A

Gendre’s solution

359
Q
  1. It penetrates large tissues poorly; hence, its use is limited to small fragments of tissue.
A

Gendre’s solution

360
Q
  1. Picrates are soluble in water; hence, tissues should not be washed in running water but rather transferred directly from fixative to 70% alcohol.
A

Gendre’s solution

361
Q
  1. It is not suitable for fixing kidney structures, lipid and mucus.
A

Gendre’s solution

362
Q
  1. It destroys cytoplasmic structures, e.g. mitochondria.
A

Gendre’s solution

363
Q
  1. It produces RBC hemolysis and removes demonstrable ferric iron from blood pigments.
A

Gendre’s solution

364
Q
  1. It reduces or abolishes Feulgen reaction due to hydrolysis of nucleoproteins.
A

Gendre’s solution

365
Q
  1. It fixes and precipitates nucleoproteins.
A

GLACIAL ACETIC ACID

366
Q
  1. It precipitates chromosomes and chromatin materials; hence, is very useful in the study of nuclear components of the cell. In fact, it is an essential constituent of most compound nuclear fixatives.
A

GLACIAL ACETIC ACID

367
Q
  1. It causes tissues (especially those containing collagen) to swell. This property is used in certain compound fixatives to counteract the shrinkage produced by other components (e.g. mercury).
A

GLACIAL ACETIC ACID

368
Q
  1. When combined with Potassium Dichromate, the lipid-fixing property of the latter is destroyed (e.g. Zenker’s fluid).
A

GLACIAL ACETIC ACID

369
Q
  1. It is contraindicated for cytoplasmic fixation since it destroys mitochondria and Golgi elements of cells.
A

GLACIAL ACETIC ACID

370
Q
  1. Concentrated acetic acid is corrosive to skin and must, therefore, be handled with appropriate care, since it can cause skin burns, permanent eye damage, and irritation to the mucous membranes. These burns or blisters may not appear until hours after exposure.
A

GLACIAL ACETIC ACID

371
Q
  1. Latex gloves offer no protection, so especially resistant gloves, such as those made of nitrile rubber, are worn when handling the compound.
A

GLACIAL ACETIC ACID

372
Q
  1. It is recommended for acid mucopolysaccharides.
A

LEAD FIXATIVES

373
Q
  1. It fixes connective tissue mucin.
A

LEAD FIXATIVES

374
Q

It takes up C02 to form insoluble lead carbonate especially on prolonged standing. This may be removed by filtration or by adding acetic acid drop by drop to lower the pH and dissolve the residue.

A

LEAD FIXATIVES

375
Q
  1. It precipitates proteins.
A

TRICHLOROACETIC ACID

376
Q
  1. Its marked swelling effect on tissues serves to counteract shrinkage produced by other fixatives.
A

TRICHLOROACETIC ACID

377
Q
  1. It may be used as a weak decalcifying agent.
A

TRICHLOROACETIC ACID

378
Q
  1. Its softening effect on dense fibrous tissues facilitates preparation of such sections.
A

TRICHLOROACETIC ACID

379
Q

It is a poor penetrating agent, hence, is suitable only for small pieces of tissues or bones.

A

TRICHLOROACETIC ACID

380
Q
  1. It is recommended for the study of water diffusible enzymes especially phosphatases and lipases.
A

ACETONE

381
Q
  1. It is used in fixing brain tissues for diagnosis of rabies.
A

ACETONE

382
Q
  1. It is used as a solvent for certain metallic salts to be used in freeze substitution techniques for tissue blocks.
A

ACETONE

383
Q
  1. It produces inevitable shrinkage and distortion.
A

ACETONE

384
Q
  1. It dissolves fat.
A

ACETONE

385
Q
  1. It preserves glycogen poorly.
A

ACETONE

386
Q
  1. It evaporates rapidly.
A

ACETONE

387
Q

provides a stable medium for transport of fresh unfixed tissues, such as renal, skin and oral mucosa biopsies, which will undergo subsequent frozen section and immunofluorescence studies.

A

MICHEL’S SOLUTION

388
Q

Medium is not suitable for transporting cells for flow cytometry or for tissues used for fluorescent in-situ hybridization (FISH).

A

MICHEL’S SOLUTION

389
Q

It is not a fixative, and is not suitable for any other use (particularly, for transporting living cells for flow cytometry).

A

MICHEL’S SOLUTION

390
Q

It should be kept refrigerated (not frozen) until use.

A

MICHEL’S SOLUTION

391
Q

Specimens may be kept in it at room temperature for 5 days while in transport until they can be delivered to the reference laboratory.

A

MICHEL’S SOLUTION

392
Q

This simple salt solution maintains pH, but does not kill most pathogens.

A

MICHEL’S SOLUTION

393
Q

Specimens received in transport medium should be washed in three changes of washing solution (10 minutes for each wash).

A

MICHEL’S SOLUTION

394
Q

It is not suitable for FISH studies.

A

MICHEL’S SOLUTION

395
Q

Adjust pH to 7.4

A

10% Neutral-Buffered Formalin

396
Q
  1. It prevents precipitation of acid formalin pigments on post​mortem tissue.
A

10% Neutral-Buffered Formalin

397
Q
  1. It is the best fixative for tissues containing iron pigments and for elastic fibers which do not stain well after Susa, Zenker’s or
    chromate fixation.
A

10% Neutral-Buffered Formalin

398
Q
  1. It requires no post-treatment after fixation and goes directly into 80% alcohol for processing.
A

10% Neutral-Buffered Formalin

399
Q
  1. It is longer to prepare; hence, is time-consuming.
A

10% Neutral-Buffered Formalin

400
Q
  1. Positivity of mucin to PAS is reduced.
A

10% Neutral-Buffered Formalin

401
Q
  1. It may produce gradual loss in basophilic staining of cells.
A

10% Neutral-Buffered Formalin

402
Q
  1. Reactivity of myelin to Weigert’s iron hematoxylin stain is reduced.
A

10% Neutral-Buffered Formalin

403
Q
  1. It is inert towards lipids, especially neutral fats and phospholipids.
A

10% Neutral-Buffered Formalin

404
Q

They are said to give improved results with immunohistochemistry.

A

Zinc formalin (unbuffered)

405
Q

There are a number of alternative formulas available some of which contain zinc chloride which is thought to be slightly more corrosive than zinc sulphate.

A

Zinc formalin (unbuffered)

406
Q

There is no need for “washing-out”.

A

Formalin

Formol-Corrosive (Formol-Sublimate)

407
Q

Tissues can be transferred directly from fixative to alcohol.

A

Formol-Corrosive (Formol-Sublimate)

HISTOPATHOLOGY (14 decks)

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