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Histopath LEC > FIXATION > Flashcards

FIXATION Flashcards

1
Q

Defined as the killing, penetration, and hardening of tissues

First and most critical step in tissue processing

A

Fixation

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2
Q

Fixation

Primary purpose:

A

Preserve the morphologic and chemical integrity of the cell in a life-like manner as possible

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3
Q

EFFECTS OF FIXATIVES

•______ soft tissues in preparation for further tissue processing

• Render cells resistant to____ caused by chemicals used in further processing

• Inhibit_____ caused by bacteria and fungi

• Minimize the risk of_____

• Act as_____ for certain stains, thus promoting or hastening staining, or inhibit certain dyes

• Reduce the risk of infections during handling and actual processing of tissues

A

Hardens

damage

decomposition

occupational infection

mordant

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4
Q

CHARACTERISTICS OF A GOOD FIXATIVE

A

• Cheap
• Stable
• Safe
• Quick
• Inhibits bacterial decomposition
• Produce minimum shrinkage
• Rapid and even penetration
• Hardens the tissue
• Makes cellular contents resistant to further processing
• Permit staining

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5
Q

FACTORS AFFECTING FIXATION

A

• Fixative of Choice
• Time
• Tissue to fixative ratio
• Penetration rate
• Thickness of specimen
• Tissue components
• pH
• Temperature
• Osmolality
• Agitation, vacuum

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6
Q

Fixative of Choice

Morphologic criteria for dx have been established based on
Formalin-Fixed Paraffin
Embedded Specimen (FFPES)

A

10% Neutral Buffered Formalin

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7
Q

Time
Must be performed as soon as possible;
_________ after blood supply is cut off

A

20-30 mins

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8
Q

Tissue-to-Fixative Ratio
•_______(tissue to fixative ratio)

A

1:10 or 1:20

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9
Q

Penetration Rate
Formalin:_____(but slows down as it goes deeper into the tissue)

A

1mm/hr

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10
Q

Thickness of Specimen
• Larger -› Longer fixation time, more fixative

• Light Microscopy:
• Electron Microscopy:

A

2cm2 x 0.4cm

1-2mm2

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11
Q

Tissue Components
• Longer Fixation time:

A

• Fibrous Tissue
• Mucus
• Fat
• Blood

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12
Q

Tissue Components

Shorter Fixation time:

A

Small of loosely textured tissues

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13
Q

рН

Optimal pH:
Use buffers

A

6 to 8

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14
Q

pH

For Electron Microscopy:

A

pH should match physiologic pH

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15
Q

• Temperature
Higher temp ->

A

faster fixation rate and autolysis

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16
Q

Optimal temp

A

Room temp to 45C

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17
Q

Tissue processor temp

A

40C

18
Q

Microwave processing temp

A

Up to 65C

19
Q

Electron microscopy temp

A

0-4C

20
Q

Tuberculosis temp

A

100C

21
Q

Rapid biopsy temp

A

60C

22
Q

Osmolality

Hypertonicity ->

Isotonicity and Hypotonicity -›

A

cell shrinkage

cell swelling

23
Q

Osmolality

maintain tissues at

A

slightly hypertonic solution (400-450 mOsm)

24
Q

TYPES OF FIXATIVE
• Based on Composition

A

Simple
Compound

25
Q

______ Made of only one component

______ Consists of two or more components of fixatives

A

Simple

Compound

26
Q

TYPES OF FIXATIVE BASED ON ACTION

A

Microanatomical
Cytological
Histochemical

27
Q

General study of tissues w/o structure alteration

A

Microanatomical

28
Q

• Cytological
________
_______

A

• Nuclear

• Cytoplasmic

29
Q

Nuclear
•_____
Glacial acetic acid has affinity to nuclear chromatin

Cytoplasmic
•_____
• HAc destroys mitochondria and Golgi bodies

A

pH ≤ 4-6

pH > 4-6

30
Q

• Preserves chemical constituents if cells and tissues

A

Histochemical

31
Q

Microanatomical

A

-10% NBF
- 10% Formol-Saline
- Heidenhain’s Susa
- Zenker’s
- Zenker-formol (Helly’s)
- Bouin’s
- Brail’s

32
Q

Nuclear

A

-Flemming’s with glacial acetic acid
- Carnov’s
- Bouin’s
- Newcomer’s
- Heidenhain’s

33
Q

Cytoplasmic

A
  • Helly’s
  • Orith’s
  • Regaud’s / Molter’s
  • Formalin with Post-charming
    -Fleming’s w/o glacial acetic acid
34
Q

Histochemical

A
  • 10% Formol Saline
  • Absolute ethanol
  • Newcomer’s
  • Acetone
35
Q

ALDEHYDE FIXATIVES

A
  1. Formaldehyde
  2. 10% formol saline
  3. 10% Neutral Buffered Formalin (NBF)
  4. Formol-Corrosive (Formol Mercuric Chloride)
  5. Gendre’s (Alcoholic Formalin)
  6. Hollande’s
  7. Glutaraldehyde
  8. Paraformaldehyde
  9. Karnovsky’s Paraformaldehyde /
    Glutaraldehyde
  10. 40% Aqueous Glyoxal
36
Q

3 types of metallic fixatives

A

Mercuric chloride
Chromates
Lead

37
Q

Mercuric Chloride

A

Zenker
Zenker-Formol (Hellv’s)
Carnoy-Lebron
[Heidenhain’s Susa
B5
Schaudinn’s

38
Q

Chromates

A

Chromic acid
[Regaurd’s/Muller’s
‘Orth’s
Potassium dichromate

39
Q

PICRIC ACID FIXATIVES

A
  1. Bouin’s
  2. Brasil’s Alcoholic Picroformol
  3. Glacial Acetic Acid
40
Q

ALCOHOL FIXATIVES

A
  1. Carnoy’s Fluid
  2. Ethanol (70 - 100%)
  3. Methanol / Wood Alcohol (100%)
  4. Isopropanol
  5. Newcomer’s Fluid
  6. Gendre’s (Alcoholic Formalin)
41
Q

OSMIC ACID FIXATIVES

A
  1. Flemming’s Solution w/ GAC
  2. Flemming’s Solution w/o GAC
  3. Trichloroacetic Acid
  4. Acetone

Histopath LEC (37 decks)

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