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HISTOPATH > TISSUE PROCESSING: FIXATION > Flashcards

TISSUE PROCESSING: FIXATION Flashcards

1
Q

Historically, FIXATION is defined as ________, ________ and, _______ of tissues

A

Killing,Penetration and Hardening

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2
Q

This tissue processing is currently defined as the alteration of tissues by stabilizing protein

A

Fixation

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3
Q

FUNCTIONS OF FIXATION:
1. Change the _________ contents of cells into ______ structures

A
  1. Soluble ; Insoluble
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4
Q

What do fixation stops?

A

Autolysis, putrefaction and decay

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5
Q

FUNCTIONS OF FIXATION:
3. ____________ to maintain the proper relationship pf cells and their ______.

A

Stabilize structures; stroma

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6
Q

What do fixation affects?

A

Refraction index

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7
Q

What are the mechanism fixatives of Fixation?

A

A. Additive
B. Non-additive
C. Coagulant
D. Non-coagulant
E. Cytologic
F. Histochemical
G. Microanatomical
H. Chemical Composition of Fixatives

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8
Q

This chemically alters the issue by bonding with it and adding themselves to the tissue

A

Additive fixative

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9
Q

Give examples of Additive fixative.

A

Formaldehyde
Mercuric chloride
Chromium trioxide
Picric acid
Glutaraldehyde
Osmium tetroxide
Zinc sulfate

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10
Q

This act on tissue without chemically combining with it.

A

Non-additive fixatives

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11
Q

Give example of Non-additive fixatives

A

Acetone and alcohol

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12
Q

This acts by creating a network that allows a solution to readily penetrate the anterior of the tissue.

A

Coagulant fixatives

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13
Q

This creates a gel that makes it difficult to penetrate by subsequent solutions. This should be cut thinly

A

Non-coagulan fixatives

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14
Q

This preserves specific cellular constituents

A

Cytologic fixatives

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15
Q

Which of the following has an acetic acid? What is their pH?

A

Nuclear fixatives: with acetic acid <4.6pH
Cytoplasmic fixative: without acetic acid >4.6pH

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16
Q

This preserves the chemical constituents of cells and tissues

A

Histochemical

17
Q

This permits the general microscopic study of tissue structure altering the structural

A

Microanatomical

18
Q

What are the factors that affect fixations?

A
  1. Temperature
  2. Specimen size
  3. Volume ratio
  4. Type of tissue or Organ
  5. Time
  6. Penetration
  7. pH
  8. Osmolality
19
Q

Fixation is mostly done at?

A

20-22’C

20
Q

Heat fixation is done at what sample?

A

Blood smear and bacteriologic smears

21
Q

What is the temp. Of DNA and RNA?

A

RNA: 45’C
DNA: 65’C

22
Q

What is the temp of formalin Incase of urgent biopsy and tissue with TB.

A

UB: Formalin is heated at 60’C
TB: Formalin is heated at 100’C

23
Q

What is the specimen size of the ff?

A

RECOMMENDED: 2cm2 x 4mm
Electron microscopy: 1 to 2 mm2
Lung edeme: 1 to 2cm

24
Q

What is the ideal fixative ratio?

A

15-20:1

25
Q

What is the volume ratio of Osmium tetroxide and Museum material?

A

OT: 5-10:1
MM: 50-100:1

26
Q

Give examples of hollow organs

A

Colon, Intestines and Gallbladder

27
Q

Intravascular Perfusion: ____________

A

Ringer’s lactate

28
Q

This refers to the interval between interruption of blood supply and time tissue is immersed in the fixative.

A

Cold Ischemia Time

29
Q

This refers to the time period the tissue is exposed to formalin

A

Fixation time

30
Q

What is the ideal time to perform fixation?

A

20-30 mins

31
Q

How long a tissue must be immersed?

A

No longer than 60 mins

32
Q

What is the minimum and maximum time of fixation?

A

6 - 48 hrs

33
Q

What is the fastest penetrating fixative?

A

Formalin

34
Q

If the formalin the fastest penetrating fixative. In an hour and 4 hours how much did the formalin penetrate?

A

1hr: 3.6mm
4hrs: 7.2 mm (@25’C, pH 7)

35
Q

Cross linking is complete in _______?

A

48 hours

36
Q

What is the recommended pH?

A

6-8 pH

37
Q

At low pH, what does Formalin produce to obscure cellular detail?

A

Dark pigment

38
Q

What solution is used as a holding solution for frozen section and kidney biopsy?

A

Isotonic solution

HISTOPATH (26 decks)

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