Draw the actual set up of fixation.
Questions:
1. What is the required volume of fixatives for routine processing?
- The required volume of fixative should be 20x the volume of the specimen if the fixative used is
formalin. However, if Osmium Tetraoxide is used, the volume should be 5x the volume of the
specimen.
2. What are the factors that affect duration of fixation?
a. Temperature
b. Size & thickness of the specimen
c. Volume ratio
d. Choice of fixatives
e. Penetration
f. Tissue storage
g. Buffer & pH
h. Osmolality
i. Concentration
3. Enumerate certain precautions during fixation.
1. Specimens should be labeled and identified properly.
2. Avoid drying out of specimen to prevent shrinkage and distortion of the tissue which
causes loss of cellular details.
3. Keep in mind the hazards and risks of using fixatives.
4. Some of the fixatives are highly corrosive which reacts to metals so avoid metal lid.
5. Carefully use fresh and suitable quality reagents in making fixatives.
6. Refrigerate but do not freeze if fixation is not yet ready or immediately possible.
7. Handle the tissue specimen with care since distortion, rough handling, or other
mechanical damage can permanently affect the morphology of the tissues, making
interpretation difficult to do.
8. The size of the tissue should not exceed in 5mm except in lung edema which varies in
size but is usually 1-2cm thick.
Questions:
1. What is the required volume of fixatives for routine processing?
- The required volume of fixative should be 20x the volume of the specimen if the fixative used is
formalin. However, if Osmium Tetraoxide is used, the volume should be 5x the volume of the
specimen.
2. What are the factors that affect duration of fixation?
a. Temperature
b. Size & thickness of the specimen
c. Volume ratio
d. Choice of fixatives
e. Penetration
f. Tissue storage
g. Buffer & pH
h. Osmolality
i. Concentration
3. Enumerate certain precautions during fixation.
1. Specimens should be labeled and identified properly.
2. Avoid drying out of specimen to prevent shrinkage and distortion of the tissue which
causes loss of cellular details.
3. Keep in mind the hazards and risks of using fixatives.
4. Some of the fixatives are highly corrosive which reacts to metals so avoid metal lid.
5. Carefully use fresh and suitable quality reagents in making fixatives.
6. Refrigerate but do not freeze if fixation is not yet ready or immediately possible.
7. Handle the tissue specimen with care since distortion, rough handling, or other
mechanical damage can permanently affect the morphology of the tissues, making
interpretation difficult to do.
8. The size of the tissue should not exceed in 5mm except in lung edema which varies in
size but is usually 1-2cm thick.
