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Histopath > Fixation > Flashcards

Fixation Flashcards

1
Q

Mechanism in fixation wherein the fixing agent is not incorporated into the tissue

A

Non-additive fixation

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2
Q

Mechanism in fixation wherein the fixing agent is taken in and becomes part of the tissue

A

Additive fixation

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5
Q

Inadequate or poor fixation will result in?

A

Poorly processed tissue

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6
Q

Disadvantage of liquid nitrogen

A

Soft tissue is liable to crack

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7
Q

Fixation helps preserve ____, ____, ____, and _____ of tissue

A

Shape, structure, intercellular relationship, and chemical constituents

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8
Q

Generally used in histochemistry and during operative procedures

A

Liquid nitrogen

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9
Q

Leaving the tissue in water will result in?

A

Cell shrinkage

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10
Q

Amount of fixative to be used for maximum effectiveness of fixation is?

A

20x the tissue volume

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11
Q

The following are additive fixatives except:
A. Formalin
B. Mercury
C. Alcohol

A

C. Alcohol

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12
Q

Types of fixative according to composition

A

Simple fixative and compound fixative

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13
Q

Type of fixative which permits the general microscopic study of tissue structures without altering the structural pattern and normal intercellular relationship of tissue in question

A

Microanatomical fixative

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15
Q

Type of fixative which has been added together to obtain optimal combined effect of their individual actions

A

Compound fixative

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16
Q

Type of cytological fixative which preserves the nuclear structures and usually contains glacial acetic acid as primary component

A

Nuclear fixative

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17
Q 
The following are nuclear fixative except for two
A. Flemming’s fluid
B. Orth’s fluid
C. Heidenhain’s susa
D. Regaud’s fluid
E. Bouin’s fluid
A

B and D. Orth’s and Regaud’s fluids are cytoplasmic fixatives

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18
Q

Leaving the tissue in air for prolonged period of time will cause?

A

Drying out and will further result in distortion of its morphologic appearance.

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19
Q

Type of cytological fixative which preserves cytoplasmic structures and does not contain glacial acetic acid

A

Cytoplasmic fixative

20
Q

Most widely used fixative

A

Formaldehyde

21
Q

pH of nuclear fixative

A

4.6 or less

22
Q

Type of cytological fixative which preserves the chemical constituent of cells and tissues

A

Histochemical fixative

23
Q

True or false:

10% formalin is achieved by mixing 10ml of formalin with 90ml of water

A

True

24
Q

True or false:
10% neutral buffered formalin is recommended for preservation and storage of surgical , post mortem, and research specimen

A

True

25
Q

True or false:

Fixation time needed for 10% neutral buffered formalin is 1/2hr - 3hrs

A

False. Fixation time is 4-24hrs

26
Q

Two of the following statements about glutaraldehyde are incorrect

  1. Glutaraldehyde is made up of formaldehyde residues linked by 3 carbon chains
  2. Specimen vial need not be refrigerated during fixation
  3. Fixation time is 1-2hrs
A

2 and 3 are incorrect.

Specimen should be refrigerated and fixation time is 1/2hr - 2hrs

27
Q

Two aldehyde fixative mixture useful for electron cytochemistry

A

Karnovsky’s paraformaldehyde- glutaraldehyde

28
Q

Types of cytological fixatives

A

Nuclear, cytological, and histochemical

29
Q

Give 5 characteristics of a good fixative

A
  1. Must be cheap, stable, and safe to handle
  2. Must be isotonic
  3. Must inhibit bacterial decomposition
  4. Must permit rapid and even penetration of tissues
  5. Must produce minimum shrinkage of tissue
30
Q

Practical considerations of fixation

A
  1. Speed
  2. Penetration
  3. Volume
  4. Duration/ time
31
Q

Diffusion time of formalin into tissue

A

1mm/hr

32
Q

Fixation time can be cut down by using?

A

Heat, vacuum, agitation, or microwave

33
Q

Give 5 effects of fixative

A
  1. Hardens soft tissues and make the handling and cutting of sections easier
  2. Inhibit bacterial decomposition
  3. Increase the optical diff of cells and tissues
  4. Make cells resistant to damage and distortion
  5. Acts as mordant or accentuators
34
Q

Types of coagulant fixatives

A
  1. Dehydrant
  2. Acidic
  3. Cross-linking
  4. Compound fixative
35
Q

Type of coagulant fixative which changes the charges of the ionizable side chains of proteins and disrupt electrostatic and hydrogen bonding

A

Acidic coagulant

36
Q

Microwave heating reduces time of fixation from more than 12hrs to less than _____

A

20minutes

37
Q 
The following are histochemical fixatives except? 
A. Formol saline 10%
B. Absolute ethyl alcohol
C. Newcomer’s fluid
D. Acetone
E. Carnoy’s fluid
A

E. Carnoy’s fluid is a nuclear fixative

38
Q

Most useful fixatives for preserving glycogen?

A
  1. Rossman’s fluid

2. Cold absolute alcohol

39
Q

Generally recommended for glycogen fixation

A

Alcoholic fixative

40
Q 
The following are simple fixatives except? 
A. Mercuric chloride
B. Formaldehyde
C. Glutaraldehyde
D. All are simple fixatives
A

D.

41
Q

Most common metallic fixative

A

Mercuric chloride

45
Q

Two mechanisms involved in fixation are_____ and _____

A
  1. Additive

2. Non-additive

Histopath (4 decks)

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