TISSUE PROCESSING: FIXATION

Question 1

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

Answer 1

Killing,Penetration and Hardening

Question 2

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

Answer 2

Fixation

Question 3

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

Answer 3

1. Soluble ; Insoluble

Question 4

What do fixation stops?

Answer 4

Autolysis, putrefaction and decay

Question 5

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

Answer 5

Stabilize structures; stroma

Question 6

What do fixation affects?

Answer 6

Refraction index

Question 7

What are the mechanism fixatives of Fixation?

Answer 7

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

Question 8

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

Answer 8

Additive fixative

Question 9

Give examples of Additive fixative.

Answer 9

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

Question 10

This act on tissue without chemically combining with it.

Answer 10

Non-additive fixatives

Question 11

Give example of Non-additive fixatives

Answer 11

Acetone and alcohol

Question 12

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

Answer 12

Coagulant fixatives

Question 13

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

Answer 13

Non-coagulan fixatives

Question 14

This preserves specific cellular constituents

Answer 14

Cytologic fixatives

Question 15

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

Answer 15

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

Question 16

This preserves the chemical constituents of cells and tissues

Answer 16

Histochemical

Question 17

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

Answer 17

Microanatomical

Question 18

What are the factors that affect fixations?

Answer 18

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

Question 19

Fixation is mostly done at?

Answer 19

20-22’C

Question 20

Heat fixation is done at what sample?

Answer 20

Blood smear and bacteriologic smears

Question 21

What is the temp. Of DNA and RNA?

Answer 21

RNA: 45’C
DNA: 65’C

Question 22

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

Answer 22

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

Question 23

What is the specimen size of the ff?

Answer 23

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

Question 24

What is the ideal fixative ratio?

Answer 24

15-20:1

Question 25

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

Answer 25

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

Question 26

Give examples of hollow organs

Answer 26

Colon, Intestines and Gallbladder

Question 27

Intravascular Perfusion: ____________

Answer 27

Ringer’s lactate

Question 28

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

Answer 28

Cold Ischemia Time

Question 29

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

Answer 29

Fixation time

Question 30

What is the ideal time to perform fixation?

Answer 30

20-30 mins

Question 31

How long a tissue must be immersed?

Answer 31

No longer than 60 mins

Question 32

What is the minimum and maximum time of fixation?

Answer 32

6 - 48 hrs

Question 33

What is the fastest penetrating fixative?

Answer 33

Formalin

Question 34

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

Answer 34

1hr: 3.6mm
4hrs: 7.2 mm (@25’C, pH 7)

Question 35

Cross linking is complete in _______?

Answer 35

48 hours

Question 36

What is the recommended pH?

Answer 36

6-8 pH

Question 37

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

Answer 37

Dark pigment

Question 38

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

Answer 38

Isotonic solution