Artifacts in Nuclear Medicine with Identifying and resolving artifacts.
Lecture (5) processing of tissue in histopathology laboratory
1.
2.
3. Provide sufficient rigidity
to the tissue.
• If the tissue had enough
rigidity then the tissue can
be cut into thin section.
• Then used for microscopic
examination.
4. Principle of processing:
1. To remove water within the
tissue.
2. To impregnate paraffin wax in
the tissue.
Paraffin wax provides support to the
tissue.
6. •Water must be removed
from the tissue.
•Why ??
1.Dehydration:
7. • Water doesn't mix with wax.
• Wet fixed tissues (in aqueous
solutions) cannot be directly
infiltrated with paraffin.
8. • To clear/ remove the dehydrating
agent
• The clearing agents is miscible
to:
— Dehydrating agent.
— Impregnating medium.
2.Clearing:
9. The tissue is infiltrated with a
supporting medium.
This supporting medium will
provide adequate rigidity of
the tissue.
• To make thin section for
next step.
3. Infiltration & impregnation:
12. 1. Dehydration should be done
gradually from low to high
concentration of dehydration
fluid.
13. 2. The tissue should be kept in the
dehydration fluid for optimal
time.
• Too much time cause the tissue
hard and brittle.
• Too little time insufficient for
removal of free water molecule
14. 3. Smaller size need less time.
• Thin 2–3 mm tissue needs less
time in dehydration fluid than
• Thick 5 mm tissue need more
time.
17. Characteristics:
• The most commonly used.
• Clear and colorless fluid.
• flammable liquid.
It needs license from the government to
purchase ethyl alcohol for laboratory use.
18. Concentration:
1. Use graduate ethanol (50, 70, 90 and 100%)
• For delicate/ soft tissue started from 30%
concentration.
2. Use anhydrous cupric sulphate in final
container
Time:
• 2 h each
Don’t immerse the tissue in the ethanol for
long time.
• Causes hard and brittle tissue.
Laboratory use:
19. Anhydrous cupric sulphate (CUSO4)
• White powder that draws water from the
alcohol.
• Helps in dehydration.
20. How to use anhydrous cupric
sulphate?
1. About 1 cm layer of this powder is kept in the
bottom of the container.
2. Then covered with 2-3 layers of filter paper.
• to prevent any colouring of the tissue.
3. When the CuSO4 becomes hydrated, the
colour of the powder changes to blue.
• This gives warning signal to change the alcohol
and the CuSO4 powder.
23. Methylated spirit
known as denatured alcohol.
Components:
• 99% ethanol
• 1% methanol / isopropyl alcohol).
Uses:
• Used in the same manner as ethanol.
40. Aims of clearing:
1. Removal of dehydrating agent (e.g.
alcohol)
• to facilitate impregnation of paraffin
wax
2.To make the tissue clear and
improve the microscopic
examination
41. • Clearing is the process which leaves
the tissues clear and transparent.
• Transparent tissue = complete
dehydration.
• Any opacity of tissue = Incomplete
dehydration.
• The amount of clearing agent should
be 40 times of the volume of tissue
for clearing.
43. Characteristics:
• Most commonly used clearing agent in the
laboratory.
• Clear
• Inflammable liquid.
44. • The small pieces of tissue are
cleared rapidly by xylene
Time:
• 30–60 min
• Note:
• Prolonged exposure to xylene may
make the tissue hard and brittle.
45. Characteristics:
• Almost similar properties as that of
xylene.
• Flammable.
• Action is slightly slower than xylene.
• Toxic.
• Prolonged exposure does not make the
tissue hard.
47. Uses:
• Used in dense tissue.
• Example: uterus, muscle.
Penetrating power:
• Chloroform is slower than xylene.
Advantage:
• Does not cause any tissue shrinkage.