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Fixation & Fixatives Flashcards

1
Q

Chemical constituent of the fixative is taken in and becomes part of the tissue by forming cross-links or molecular complexes and giving stability to the protein

A

ADDITIVE FIXATION

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2
Q

Fixing agent is not incorporated into the tissue but alters the tissue to H bonds of
certain groups within the protein molecule

A

NON-ADDITIVE FIXATION

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3
Q

pH for satisfactory fixation

A

Between pH 6 and 8

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4
Q

Electron microscopy workouts and histochemistry examination ideal temperature is

A

0-4°C

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5
Q

Formalin heated to ___ is sometimes used for rapid fixation of very urgent biopsy
specimens

A

60°C

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6
Q

Formalin at 100°C can be used
to fix tissues with

A

tuberculosis

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7
Q

The best results are usually obtained using

A

slightly hypertonic solutions

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8
Q

PRACTICAL CONSIDERATIONS OF FIXATION

A

-Speed
-Penetration
-Volume
-Duration of fixation

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9
Q

They act as mordants or accentuators to promote
and hasten staining, or they may inhibit certain dyes
in favor of another

A

Fixatives

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10
Q

Lead Fixatives

A
  • Picric acid
    -Acetic acid
    -Acetone
    -Osmium tretoxide
    -Alcohol
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11
Q

permit the microscopic
study of tissue structures without altering the
structural pattern and normal intercellular
relationship of tissues

A

Microanatomical Fixatives -

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12
Q
  • preserve specific parts and
    particularly microscopic elements of the cell itself
A

Cytological Fixatives

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13
Q

preserve nuclear structures
(e.g. chromosomes) in particular

A

Nuclear Fixatives

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14
Q

Usually contain glacial acetic acid as their primary component due to its affinity for nuclear chromatic

A

Nuclear Fixatives

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15
Q

must never contain glacial acetic acid since it destroys the mitochondria and golgi bodies; pH of more than 4.6

A

Cytoplasmic Fixatives

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16
Q

preserve chemical
constituents of cells and tissues

A

Histochemical Fixatives

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17
Q

Phospholipids which contain amino groups are fixed
by

A

aldehydes

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18
Q

should be used for
demonstrating lipid in tissues by a general lipid stain

A

Cryostat or frozen sections

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19
Q

Improved ultrastructural demonstration of lipids has
been achieved by post-fixing in

A

imidazole osmium
tetroxide

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20
Q

Cholesterol may be fixed with ___ for ultrastructural demonstration.

A

digitonin

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21
Q

can enhance better retention of
glycogen

A

Celloidin coating

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22
Q

Two aldehyde fixative mixture have been particularly
useful for electron cytochemistry

A

Karnovsky
paraformaldehyde-glutaraldehyde

23
Q

Penetrate tissue rapidly, preserves
morphology and enzyme activity at low
concentrations
- Useful for immersion fixation of surgical
biopsies

24
Q

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

A

10% FORMOL SALINE

25
fixation of central nervous tissues and post-mortem tissues for histochemical examination
10% FORMOL SALINE
26
Fixation time for 10% Formol Saline
24 hours at 35 °C OR 48 hours at 20-25 °C
27
recommended for preservation and storage of surgical, post-mortem and research specimens
10% NEUTRAL BUFFERED FORMALIN OR PHOSPHATE BUFFERED FORMALIN
28
Fixation time for 10% NEUTRAL BUFFERED FORMALIN OR PHOSPHATE BUFFERED FORMALIN
4-24 hours
29
prevents precipitation of acid formalin pigments; best tissue fixative for tissues containing iron pigments and for elastic fibers that does not stain well after Susa, Zenker or Chromate fixation
10% NEUTRAL BUFFERED FORMALIN OR PHOSPHATE BUFFERED FORMALIN
30
Reactivity of myelin to Weigert's iron hematoxylin stain is reduced; Inert towards lipids, especially neutral fats and phospholipids
10% NEUTRAL BUFFERED FORMALIN OR PHOSPHATE BUFFERED FORMALIN
31
recommended for routine post-mortem tissues
FORMAL-CORROSIVE
32
Forms mercuric chloride deposits; does not allow frozen tissue sections to be made
FORMAL-CORROSIVE
33
95% Ethyl alcohol saturated with picric acid ➢ Strong formaldehyde solution
Alcoholic Formalin (Gendre's) FIxative
34
Good for preservation of glycogen and for micro-incineration technique; Used to fix sputum since it coagulates mucus
Alcoholic Formalin (Gendre's) FIxative
35
Produces gross hardening of tissues; Causes partial lysis of RBC; Preservation of iron containing pigments is poor
Alcoholic Formalin (Gendre's) FIxative
36
made up of two formaldehyde residues linked by three carbon chains
Glutaraldehyde
37
MOST COMMON METALLIC FIXATIVE
MERCURIC CHLORIDE
38
ROUTINE FIXATIVE OF CHOICE for preservation of cell detail in tissue photography
MERCURIC CHLORIDE
39
widely used secondary fixative reacting with a number of amino acid residues and accompanied by spectroscopic changes, probably due to histidine residues
MERCURIC CHLORIDE
40
Recommended for fixing small pieces of liver, spleen, connective tissue fibers and nuclei
ZENKER’S FLUID
41
Recommended for trichrome staining ■ Permits brilliant staining of nuclear and connective tissue fibers -Compatible with most stains ■ Act as a mordant
ZENKER’S FLUID
42
Excellent microanatomic fixative for pituitary gland, bone marrow and blood containing organs such as spleen and liver
ZENKER-FORMOL (HELLY'S SOLUTION)
43
Main fixative for tumor biopsies especially the skin. Excellent cytologic fixative
Heidenhain's Susa
44
Used for bone marrow biopsies
B-5 Fixatives
45
Recommended for demonstration of chromatin, mitochondria, mitotic figures, Golgi bodies, RBC and colloid containing tissues
REGAUD'S (MULLER) FLUID
46
Deteriorates and darkens on standing (must always be freshly prepared)
REGAUD'S (MULLER) FLUID
47
Fixation TIme for Orth's Fluid
36-72 hours
48
Recommended for early degenerative process and tissue necrosis; Demonstrates rickettsiae and other bacteria
Orth's Fluid
49
Normally used in strong saturated aqueous solutions ➢ This fixative also dyes tissues producing yellow color.
Picric acid
50
recommended for fixation of embryos and pituitary biopsies
Bouin's solution
51
better and less messy than Bouin's; excellent fixative for glycogen
BRASIL'S ALCOHOLIC PICROFORMOL FIXATIVE
52
Normally used in conjunction with other fixatives to form a compound solution ➢ Solidifies at 17 °C
GLACIAL ACETIC ACID
53

Histopath (3 decks)

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