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Histopath must knows > FIXATION > Flashcards

FIXATION Flashcards

1
Q

Primary aim of FIXATION

A

preserve the morphologial and chemical integrity of the cell in as life-like manner as possible

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2
Q

Most important chemical reaction in fixation?

A

STABILIZE THE PROTEIN

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3
Q

Fixation is best carried at what ph?

A

Neutral pH - pH 7
range 6-8)

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4
Q

Give the optimum temperature of fixation of the ff;
1.Electron microscope
2. tissue processor
3. Fast formalin
4. M. tuberculosis
5. Mast cells

A
  1. Electron microscope 0-4 deg. cel.
  2. Tissue processor 40 deg. cel.
  3. Fast formalin 60 deg cel
  4. M. tuberculosis 100 deg cel
  5. Mast cells at RT
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5
Q

Concentration of FORMALIN, GLUTARALDEHYDE and for EM

A

FORMALIN - 10%
GLUTARALDEHYDE - 3%
EM - 0.25%

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6
Q

How do we fix a specimen suspected for CJD?

A

Immerse in formalin (48 hrs) –> Formic acid (1 hr) –> Formalin (48 hrs)

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7
Q

Alcoholic formalin is AKA

A

Gendre’s fixative

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8
Q

Metallic fixatives and their examples
Mercuric Chloride (BHZZ)
Chromate (CROP)

A

Mercuric Chloride
B-5 fixative
Heidenhain’s Susa
Zenker’s fluid
Zenker-formol (Helly’s fluid)

Chromate
Chromic acid
Regaud’s sol’n
Orth’s sol’n
Potassium dichromate

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9
Q

Alcoholic Fixatives (MINCE)

A

Methyl alcohol (100%)
Isopropyl alcohol (95%)
Newcomer’s fluid
Carnoy’s fluid
Ethyl alcohol (70% - 100%)

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10
Q

Give examples of Osmium tetroxide

A

Flemming’s sol’n
Flemming’s sol’n without acetic acid

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11
Q

A microanatomical fixative must never contain ______ because it inhibits hematoxylin

A

Osmium tetroxide

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12
Q

Give examples of Microanatomical fixatives (10,10 HFZZBB)

A

10% Formol saline
10% NBF
Heidenhain’s susa
Formol Sublimate
Zenker’s sol’n
Zenker formil (Helly’s)
Bouin’s solution
Brasil’s solution

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13
Q

A nuclear fixative must contain ______ as their primary component due to its affinity for nuclear chromatin

A

GAA

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14
Q

Nuclear fixative includes? BFNCH

A

Bouin’s
Flemming’s
Newcomer’s
Carnoy’s
Heidenhain’s Susa

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15
Q

pH for nuclear fixatives?

A

pH of less than 4.6

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16
Q

Cytoplasmic must never contain what compound? Give its examples HROFF

A

Must never contain GAA
Helly’s (Zenker formil
Regaud’s
Orth’s
Flemming’s fluid w/o acetic acid
Formalin with post chroming

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17
Q

Give the examples of Histochemical fixative 10% FANA

A

10% Formol saline
Absolute ethyl alcohol
Newcomer’s
Acetone

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18
Q

Both histochemical and nuclear

A

Newcomer’s solution

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19
Q

Both microanatomic and nuclear

A

Heidenhain’s susa

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20
Q

Both a microanatomic and cytoplasmic

A

Zenker formol (Helly’s)

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21
Q

Both microanatomic and histochemical

A

10% Fomol saline

22
Q

Secondary fixation may be done when?

A

Before dehydration and on deparaffinized sections BEFORE staining

23
Q

Process of post-chromatization?

A

primary fixed tissue placed in aquatic. sol’n of 2.5% to 3% potassium dichromate for 24 hrs

24
Q

What is used to remove excess chromate from tissues fixed in Helly’s, Zenker’s and Flemming’s excess formalin and osmic acid

A

Tap water

25
Q

Used to wash out excess amount of picric acid

A

50% - 70% alcohol

26
Q

Used to remove excessive mercuric fixatives

A

Alcoholic iodate

27
Q

3 F in lipid fixation

A

FATS are best demonstrated in FROZEN SECTION using FORMALIN as the fixative

28
Q

Phospholipids are fixed by?

A

aldehydes

29
Q

Cholesterol can be fixed with ______ for ultrastructure

A

digitonin

30
Q

Carbohydrate fixation (GAP)

A

GLYCOGEN can be fixed in ALCOHOLS and PICRIC ACID

31
Q

Most commonly used fixative for Amino Acid histochem or protein fixation

A

Neutral buffered formol saline or formaldehyde vapor

32
Q

Electron Microscope Fixatives ‘GOPKZ”

A

Glutaraldehyde
Osmium tetroxide
Paraformaldehyde
Karnovsky
Zamboni fluid

33
Q

Concentration of Formalin available in commcercial sol’n

A

37% to 40% considered as 100%

34
Q

How do we remove paraformaldehyde deposits

A

removed via filtration or adding 10% methanol

  • methanol can be added as a preservative for formaldehyde
35
Q

Methods in removing formalin pigments

A
  1. Picric acid (saturated alcoholic solution of picric acid)
  2. Kardasewtsch’s method (Ethyl alcohol and ammonia water
  3. Lillie’s method (ammonia water, hydrogen peroxide, acetone)
36
Q

Recommended fixative for CNS and general post-mortem tissues

A

10% Formol saline

37
Q

Best fixative for iron pigment, give it’s composition

A

10% NBF
Sodium dihydrogen phosphate
Disodium hydrogen phosphate
40% Formaldehyde
Distilled water

38
Q

It fixes and dehydrates at the same time, a good preservative of glycogen and for micro incineration technique

A

Alcoholic formalin (Gendre’s fluid)
- 95% ethanol saturated with picric acid
- Formaldehyde
- Glacial Acetic Acid

39
Q

Fixative satisfactory for EM

A

Glutaraldehyde

40
Q

This is the most common metallic fixative and when fixed it it usually contains black precipitates of ____ except?

A

mercury chloride
Except Susa
and can be removed by DEZENKERIZATION

41
Q

MERCURIC CHLORIDE STOCK SOLUTION

A
  • mercuric chloride
  • potassium dichromate
  • Sodium sulfate
  • distilled water
42
Q

Routine fixative of choice for preservation of cell detail in TISSUE PHOTOGRAPHY

A

MERCURY CHLORIDE

43
Q

What does Zenker formol (Helly’s) stain? PBB

A

Pituitary gland
Bone marrow
Blood-containing organs

44
Q

Excellent cytologic fixative recommended for tumor biopsies especially for the skin

A

Heidenhain’s susa

45
Q

Fixative used for the cytology of bone marrow

A

B-5 fixatives

46
Q

Regaud’s fixative is recommended for? GMRC

A

Golgi bodies, Mitochondria, RBC, Colloid containing tissue

47
Q

Orth’s fluid is for?

A

Study of early degenerative processes and tissue necrosis, also recommended for the demonstration of Rickettsia

48
Q

This type of fixative is recommended for Acid mucopoysaccharides

A

Lead fixative

49
Q

Advantages of Picric acid fixatives, GAP

A

Glycogen demo
Suitable for ANILINE stains
Prevents small fragments to be overlooked due to its yellow stain

50
Q

Fixes and dehydrates at the same time

A

Carnoy’s fixative

51
Q

Gives the most usable DNA fragments for PRC

A

70% to 100% ethyl alcohol

52
Q

Fastest fixative (CURL)

A

Carnoy’s fixative for
Chromosome
Urgent biopsy
Rabies
Lymph glands/nodes

Histopath must knows (4 decks)

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