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MTAP3
Histopathology
PROBLEM-REASON-REMEDY
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Cards (56)
Brittle or hard tissue
REASON:
Prolonged
fixation
,
dehydration
,
clearing
,
paraffin infiltration
Overheated
paraffin oven
Drying out
of tissue before actual fixation
Brittle or hard tissue
REMEDY:
Softened by soaking in a small dish or bowl containing
water
with
detergent
,
phenol
or
Molliflex
Clearing agent turns milky as soon as tissue is placed in it
REASON:
Water
not completely removed
Incomplete
dehydration
Clearing agent turns milky as soon as tissue is placed in it
REMEDY:
Repeat
dehydration
with
absolute alcohol
Clear again
On trimming, tissue smells of clearing agent
REASON:
Clearing agent
not completely removed
Insufficient
impregnation
On trimming, tissue smells of clearing agent
REMEDY:
Block is
trimmed
down nearest to the tissue
Remaining wax is
melted
on embedding oven
Paraffin impregnation
is repeated
Change paraffin at least once before blocking
Tissue is opaque, section cutting is difficult due to presence of alcohol
REASON:
Insufficient
clearing
Tissue is opaque, section cutting is difficult due to presence of alcohol
REMEDY:
Repeat
clearing
If object has already been embedded, prolong clearing up to
12
hours, then
re-embed
Tissue shrinks away from wax when trimmed
REASON:
Insufficient
dehydration
Incomplete
clearing
and
impregnation
Tissue shrinks away from wax when trimmed
REMEDY:
Repeat whole procedure
Tissue is soft when block is trimmed
REASON:
Incomplete
fixation
Tissue is soft when block is trimmed
REMEDY:
Repeat whole procedure
Air holes found on tissue during trimming
REASON:
Incomplete
impregnation
Air holes found on tissue during trimming
REMEDY:
Repeat
impregnation
On trimming, wax appears crystalline
REASON:
Contaminated
wax
Block not
cooled rapidly
enough
On trimming, wax appears crystalline
REMEDY:
Re-embed
in
freshly filtered wax
Paraffin block, after cooling, is moist and crumbles
REASON:
Insufficient
paraffin impregnation
Paraffin block, after cooling, is moist and crumbles
REMEDY:
Repeat
paraffin impregnation
, then
re-embed
Sections fail to form ribbons
REASON:
Surfaces and edges of the block are
not parallel
REMEDY:
Re-trim
the block
Sections fail to form ribbons
REASON:
Horizontal surface of the block is
not parallel
to the knife
REMEDY:
Re-adjust
and
re-orient
the block
Sections fail to form ribbons
REASON:
Paraffin wax is
too hard
REMEDY:
Coat horizontal edges
of the block with wax of
lower melting point
Sections fail to form ribbons
REASON:
Knife is
tilted
too much
REMEDY:
Reduce tilt
Sections fail to form ribbons
REASON:
Sections are
too thick
REMEDY:
Re-adjust
the
thickness
of the sections
Sections fail to form ribbons
REASON:
Knife is
dull
REMEDY:
Hone
and
strop
Sections roll up on cutting so that they adhere and get broken against the knife edge
REASON:
Knife is
blunt
REMEDY:
Sharpen
the knife
Sections roll up on cutting so that they adhere and get broken against the knife edge
REASON:
Tilt
of knife is too great
REMEDY:
Reduce
the
tilt
Sections roll up on cutting so that they adhere and get broken against the knife edge
REASON:
Knife edge is
dirty
REMEDY:
Clean
the knife edge
Ribbon is curved, crooked or uneven instead of straight
REASON:
Blunt of dull spot on the knife =
irregular
knife edge
REMEDY:
Adjust
the knife so that knife edge will present a
uniformly sharp edge
to the block
Sharpen
Ribbon is curved, crooked or uneven instead of straight
REASON:
Edges of the block are not parallel but
round
or
wedge
shape
REMEDY:
Re-trim
the block
Ribbon is curved, crooked or uneven instead of straight
REASON:
Knife is
not parallel
to the block
REMEDY:
Readjust
knife and block
Ribbon is curved, crooked or uneven instead of straight
REASON:
Paraffin is
impure
REMEDY:
Repeat
impregnation
using
pure wax
Sections are compressed, wrinkled, or jammed
REASON:
Knife is
blunt
or
dull
REMEDY:
Re-sharpen
the knife
Sections are compressed, wrinkled, or jammed
REASON:
Paraffin block is
warm
and
soft
REMEDY:
Cool
the block on
ice water
until firm
Sections are compressed, wrinkled, or jammed
REASON:
Knife edge is coated with
paraffin
REMEDY:
Clean
the knife edge
Sections are compressed, wrinkled, or jammed
REASON:
Sections are
too thin
REMEDY:
Readjust
thickness
of section
Sections are compressed, wrinkled, or jammed
REASON:
Microtome set screw is
loose
REMEDY:
Tighten
the screw
Sections are compressed, wrinkled, or jammed
REASON:
Tilt of knife is
too vertical
REMEDY:
Reduce
the tilt
Sections are squashed (width of each section is less than that of block)
REASON:
Bevel of knife is
lost
due to
incorrect sharpening
REMEDY:
Re-sharpen, using a
knife back
or
automatic knife sharpener
A hole is formed in the section
REASON:
Bubble
or
dirt
formed in the embedding medium
REMEDY:
Re-embed in
freshly filtered wax
if necessary
A hole is formed in the section
REASON:
Hard spot
in tissue due to
calcium
REMEDY:
Once embedded in paraffin wax, decalcification is impractical; use a
base-sledge
microtome with a
wedge
knife
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