Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

HISTO > Fixation > Flashcards

Fixation Flashcards

1
Q

Primary & Secondary Aim of fixation

A

1° - Preserve
2° - Protect & harden tissue

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Recommended volume (fixative:tissue)

A

10-20:1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Volume ratio for
1. osmium tetraoxide
2. museum prep
3. traditional

A
  1. 5-10:1
  2. 50-100:1
  3. 10-25:1
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

pH for fixative

A

Neutral 7 (6-8 pH)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

thickness of the section

A

LM: 2 cm2
EM: 1-2 mm2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

osmolality of fixative

A

400-450 mOsm/kg (slightly hypertonic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Fixative must be ___ causing minimal alterations of cells & constituents

A

isotonic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Physical methods of fixation

A
  • Heat
  • Microwave
  • Freeze drying
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Metallic fixative
Examples of Mercuric chloride (BHZZ)

A

B-5 fixative
Heidenhain’s susa
Zenker’s
Zenker-formol (Hellu’s)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Metallic fixative
Examples of chromate (CROP)

A

Chromic acid
Regaud’s soln
Orth’s soln
Potassium dichromate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Picric acid fixatives

A

Bouin’s
Brasil’s
“BB Picric”

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Alcohol fixatives

A

“MINCE”
Methyl alcohol (100%)
Isopropyl alcohol (95%)
Newcomer’s
Carnoy’s
Ethyl alcohol (70-100%)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Osmium tetraoxide fixative

A

Flemming’s soln w/ or w/o acetic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Micro anatomical fixatives must never contain

A

Alcohol & osmium tetraoxide (inhibits hematoxylin)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Nuclear fixatives contains __ at a pH of __

A

glacial acetic acid
pH of 4.6 or less

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Cytoplasmic fixatives must never contain

A

“OFF HeR”
glacial acetic acid (destroys mitochondria & golgi bodies)
pH of more than 4.6

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Histochemical fixative includes

A

“10% FANA”
10% formalin
Abs ethanol
Newcomer’s
Acetone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Both microanatomic & nuclear fixative

A

Bouin’s & Heindenhain’s susa

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Both histochemical & nuclear

A

Newcomer’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Both microanatomical & histochemical

A

10% formol saline

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Both microanatomic & cytoplasmic

A

Helly’s (Zenker formol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Factors that enhance fixation

A
  • Size & thickness (⬇️)
  • Agitation
  • Moderate heat
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Factors that retard fixation

A

Increase size & thickness
Cold temp
Presence of MBF (mucus, blood, fat)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Creating a covalent bond between protein & aldehyde

A

Cross-linking fixative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

Act by reducing the solubility of protein molecules & disrupting hydrophobic interactions

A

Precipitating/denaturing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Done before dehydration & before staining

A

Secondary fixation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

form of 2° fixation where tissue is placed in 2.5-3% potassium dichromate for 24 hrs for cyto preservation

A

post-chromatiziation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Process of removing fixative

A

Washing out

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Used to remove excessive mercuric fixative

A

Alcohol iodine

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Used to remove excess picric acid

A

50-70% alcohol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Fixatives effective for preservation of lipids

A

mercuric chloride & potassium dichromate & formalin

X alcohol & acetone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

Fixatives for carbohydrates

A

alcoholic fixatives

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Fixatives for amino acid histochemistry

A

NBF saline or Formaldehyde vapor

34
Q

Fixatives for electron microscopy

A

“GOPKZ”
Glutaraldehyde
Osmium tetraoxide
Paraformaldehyde
Karnovsky’s
Zamboni

35
Q

Satisfsctory fixative for both morpho & IHC

A

Formalin

36
Q

artifact eliminated or reduced by fixation in phenol-formalin

how to completely stop the formation?

A

Formalin pigments

using NBF

37
Q

Artifacts found in liver biopsies with an intense eosinophilic staining (in H&E stains)

A

Crush artifacts

38
Q

Difficulty: Removal of substances soluble in fixing agent

Cause?

A

Wrong choice of fixative

39
Q

Difficulty: Presence of artifact pigments

Cause?

A

Incomplete washing of fixative

40
Q

Difficulty: Tissues are soft & feather-like consistency

Cause?

A

Incomplete fixation

41
Q

Difficulty: Shrinkage & swelling of cells & tissue structure

Cause?

A

Overfixation

42
Q

Difficulty: Tissue blocks are brittle & hard

Cause?

A

Prolonged fixation

43
Q

What will happen if Formalin is unbuffered & used on blood containing tissues

A

Formation of abundant brown pigment granules (blackening of hemoglobin)

44
Q

Good for
- preserving fat & mucin
- frozen tissues are easily prepared
- colored tissue photography
- nervous tissue demonstration

A

10% Formalin

45
Q

Prolonged storage of formaldehyde at low temp causes

A

Precipitation of white paraformaldehyde deposites

46
Q

How to remove paraformaldehyde deposits

A

Filtration or adding 10% methanol

47
Q

Concentrated solution should NEVER be __ since it might violently explode

A

Neutralized

48
Q

Removal of formalin pigments

A
  • Picric acid
  • Kardasewitsch’s
  • Lillie’s
49
Q

Best fixative for iron pigments

A

10% Neutral Buffered Formalin

50
Q

Composition for 10% NBF

A

Sodium dihydrogen phosphate
Disodium hydrogen phosphate
Distilled H2O
40% formaldehyde

51
Q

Recommended for routine post-mortem tissues

A

Formol-corrosive (formol-sublimate)

52
Q

Composition for alcoholic formalin (Gendre’s fluid)

A

95% ethanol saturated w/ picric acid
Formaldehyde
Glacial acetic acid

53
Q

Depolymerizes back to formalin when heated

A

Paraformaldehyde

54
Q

Satisfactory for EM & preserves cellular structures better than formaldehyde

A

Glutaraldehyde

55
Q

All mixtures comtaining HgCl contain black precipitates except __

A

Susa

56
Q

Removal of mercury deposits are done by

A

Dezenkerization:
0.5% iodine solution in 70% ethanol for 5-10 mins
rinsed w/ H2O & decolorized for 5 mins

57
Q

Mecuric chloride stock soln

A

Mercuric chloride
Potassium dichromate
Sodium sulfate
Distilled H2O

58
Q

DONT’S for mercuric chloride fixatives

A

Don’t use metallic forceps & caps
It must not go through the drain

59
Q

Good for Trichrome staining & Tissue photography

A

Mercury chloride

60
Q

Recommended for small pieces of liver, spleen but remember to add Glacial acetic acid before use

A

Zenker’s fluid

61
Q

Excellent for Pituitary gland, Bone marrow, Blood organs but remember to add formaldehyde before use

A

Zenker formol (Helly’s)

62
Q

Recommended for skin tumor biopsies that doesn’t produce any black ppt

A

Heidenhain’s susa

63
Q

Used in 3% aq. soln that preserves mitochondria at a pH of 4.5 to 5.2

A

Potassium dichromate

64
Q

Used for demonstration of Rickettsia

A

Orth’s fluid

65
Q

Recommended for fixing Golgi bodies, Mitochondria, RBCs & Colloid

A

Regaud’s (Muller’s)

66
Q

Recommended for Acid mucopolysaccharides

A

Lead fixatives

67
Q

It dyes the tissue yellow but can be removed by tx w/ acid/lithium carbonate
Excellent for glycogen demonstration

A

Picric acid

68
Q

Not suitable for fixing kidney structures, lipid & mucus

A

Bouin’s

69
Q

what happens to glacial acetic acid at 17°C

A

it solidifies

70
Q

Fixes & precipitates nucleoproteins

A

Glacial acetic acid

71
Q

If lesser concentrated solutions of alcoholic fixatives are used, what happens to the cell

A

swell

72
Q

Gives the most usable DNA fragments for PCR

A

70-100% ethyl alcohol

73
Q

Recommended for Chromosomes, Urgent biopsy, Rabies, Lymph nodes & its the fastest

A

Carnoy’s

74
Q

Rapid freezing
Quenching temp:
Sublimation temp:

A

Quenching: -160 to -180°C
Sublimation: -30 to -40°C

75
Q

Freeze drying substitute

A

Rossman’s formula or in 1% acetone

76
Q

If fixation is not immediately possible, what to do?

A

Refrigerate
DO NOT FREEZE

77
Q

Hollow organs should be packed with

A

cotton soaked fixative/completely opened before its immersed

78
Q

How to fix human brains

A

must be floating & suspended by a cord tied under the circle of willis to prevent flattening

79
Q

Should eyes be dissected before they are fixed?
What to do?

A

NOOO
Inject formol-alcohol before immersing

80
Q

Water should not be used for these tissues bc its soluble

A

Glycogen

81
Q

Wash excess mucus using

A

NSS

82
Q

What method is used to fix hard tissues

A

Lendrum’s method
- immersing it in 4% aq phenol soln for 1-3 days

HISTO (8 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions