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Fixation Flashcards

1
Q

What is the first and most critical step in histotechnology?

A

Fixation

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2
Q

The ideal volume of the fixative is _____ greater than the size or volume of the specimen.

A

10 to 20 times

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3
Q

What is the result of tissue digestion by lysosomes that are released when organelle membranes rupture?

A

Autolysis

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4
Q

What is the most common mechanism for fixation whereby the effect is induced by dehydrants, such as alcohol or acetone?

A

Denaturation

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5
Q

What type of physical fixation is the most widely used in routine laboratories?

A

Microwave fixation

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6
Q

What type of physical fixation involves freeze drying but is not usually applied to diagnostic tissue specimens?

A

Cryopreservation

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7
Q

What method of fixation involves immersing the specimen in the fixative solution?

A

Chemical fixation

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8
Q

What will happen to the tissues if it was immersed in a hypotonic solution?

A

Tissues will swell

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9
Q

What will happen to the tissues if it was immersed in a hypertonic solution?

A

Tissues will shrink

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10
Q

What is the usual range for the pH during fixation?

A

6-8

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11
Q

Enumerate the factors involved in fixation.

A

● Hydrogen ion concentration
● Temperature
● Thickness of section
● Concentration
● Duration of fixation

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12
Q

What is the preferred thickness of the section for tissue block for electron microscopy?

A

1-2 mm^2

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13
Q

What is the preferred thickness of the section for tissue block for light microscopy?

A

2 cm^2 (no more than 0.4 cm)

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14
Q

What is the usual duration for primary fixation in buffered formalin?

A

2-6 hours

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15
Q
  • accentuate absorbance for the next procedure
  • promote and hasten staining
A

accentuator

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16
Q

What are the 2 types of fixative according to composition?

A
  1. Simple fixative
  2. Compound fixative
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17
Q

What are the 2 types of fixative according to action?

A
  1. Microanatomical fixatives
  2. Cytological fixatives
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18
Q

What type of fixative according to action permits the general microscopy study of tissue structure without altering the structures?

A

Microanatomical fixatives

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19
Q

What type of fixative according to action preserves a specific part of the cell itself?

A

Cytological fixatives

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20
Q

What is formed from the precipitation of formaldehyde that is usually obtained as a fine white powder, which depolymerizes back to formalin when heated?

A

Paraformaldehyde

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21
Q

What fixative is a gas produced by the oxidation of methyl alcohol, and is soluble in water to the extent of 37-40% weight in volume?

fixative of choice!

A

Formaldehyde

22
Q

Identify the fixative.

  • preserve cadavers
  • for CNS and postmortem tissues
A

10% Formol Saline

23
Q

Identify the fixative.

  • best fixative (optimal choice!)
A

10% Neutral Buffered Formalin

24
Q

Identify the fixative.

  • made of potassium salts + formalin
A

Kaisserling’s animal cells

25
Identify the fixative. - larger molecule than formaldehyde - more stable but more expensive - for **electron microscopy**
Glutaraldehyde
26
Identify the fixative. - **most common** metallic fixative - for **tissue photography** - forms black granular deposits
Mercuric chloride
27
Identify the fixative. - for fixing small pieces of liver, spleen, connective tissue fibers and nuclei - mercuric-chloride + glacial acetic acid
Zenker's fluid
28
Identify the fixative. - Mercuric chloride + 40% formaldehyde
Zenker-formol (helly's solution)
29
Identify the fixative. - Made up of MgCl2, glacial acetic acid, and formalin - for **tumor skin biopsy** | uses silver impregnation
Heidenhain's Susa Solution
30
Identify the fixative. - for **bone marrow** biopsy
B-5 fixative
31
Identify the fixative. - **Alcohol-containing mercury** fixative - used for wet smear preparation and connective tissues
Schaudinn's fixative
32
Identify the fixative. - fixes **carbohydrates** - precipitate all CHON
chromic acid
33
Identify the fixative. - preserve **lipid** and **mitochondria**
Potassium dichromate
34
Identify the fixative. - 3% potassium dichromate + 40% formaldehyde - for demonstration of chromatin, mitochondria, mitotic figures, golgi bodies, RBC, and colloid-containing tissue
Regaud's fluid
35
Identify the fixative. - for early degenerative processes and tissue necrosis - **brain tissue**
Orth's fluid
36
Identify the fixative. - **lead**-containing - used for the preservation of glycogen mucopolysaccharide, and amyloid - fixes connective tissue **mucin** - forms insoluble lead carbonate
Lillie's fixative
37
Identify the fixative. - explosive hazard in dry form - stains **yellow**
picric acid
38
Identify the fixative. - fixate **embryos** and **pituitary** biopsy
Bouin's solution
39
Identify the fixative. - picric acid + 37% formaldehyde + ethanol + trichloroacetic acid - excellent fixative for **glycogen**
Brasil's alcoholic picroformol
40
Identify the fixative. - for fixing **dry and wet smears**, blood smears, and bone marrow tissues
100% methyl alcohol | *methanol*
41
What is the usual concentration of ethyl alcohol?
70-95-100%
42
Identify the fixative. - for **sputum** specimens - made up of alcoholic formalin
Gendre's fixative
43
Identify the fixative. - for mucopolysaccharides and nuclear protein
Newcomer's fluid
44
Identify the fixative. - most common chrome-osmium acetic acid fixative - for **nuclear structures**
Flemming's solution
45
What are the two fixatives used for fixing brain tissue for the diagnosis of rabies?
Acetone and Carnoy's fluid
46
What solution is used for washing out **c**hromates, **f**ormalin, and **o**smic acid?
Tap water
47
What solution is used for washing out excess **picric acid** from bouin's solution?
50-70% alcohol solution
48
What solution is used for washing out excessive mercuric fixative? | Dezenkerization
* Alcoholic iodine * Langeron's iodine
49
What refers to the process of removing excess fixative from the tissue after fixation?
washing out
50
What is the fastest fixative?
Carnoy's Fluid
51
What solution is used for washing out melanin pigments?
pyrogallic acid

Histopathology (12 decks)

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