sectioning Flashcards
process of cutting tissues into uniformly thin slices for microscope studies
sectioning
t/f microtomes are instruments used for cutting thick tissue sections of 20-30 u
F – cut extremely thin slices of tissues called sections of 4-15 u (average of 4-6 u)
the thickness of tissue sections is measured in microns (µ), where 1 micron equals ________ millimeter, _____ of an inch
1/1000th of a millimeter
1/25000th of an inch
Select: General types of tissue sections
A) Paraffin Sections
B) Celloidin Sections
C) Frozen Sections
D) Rubberized Sections
A B C
rocking and rotary microtomes can create ____ sections
paraffin sections
T/F Celloidin sections are typically used for cutting tissues that are fixed and frozen with CO2
F - cut using a sliding microtome, typically from tissues like the temporal bone in EDTA
material commonly used in frozen sections for cutting fresh or fixed tissues in a cryostat
CO2
cut from tissues that have been fixed and frozen w/ CO2 or for fresh or fixed tissues frozen w/ the cryostat
frozen sections
t/f microtome knives can use blades made of steel, glass, or diamond depending on the specimen and desired thickness
t
OOO: Type of microtome knife
A) Standard Steel Blade
B) Glass Knife
C) Carbon Blade
D) Diamond Knife
C
Coarse trimming of paraffin blocks is done until about _____ mm of wax remains on all sides of the tissue.
2 mm
T/F when trimming blocks, attempting to trim large pieces of wax can lead to splitting and exposure of tissue
t
term used for removing wax until the tissue surface is exposed, done at approximately 30 microns at a time
coarse trimming (facing)
fine trimming is done by setting the thickness adjuster to _____ microns, trimming away the surface block until the tissue is partly exposed.
15 microns
T/F The wedge-shaped microtome knife is best for cutting soft, thin tissue sections
F - wedge-shaped knives are typically used for harder, larger tissues
microtome knife profile shaped with a concave side on both planes
biconcave
T/F a chisel-shaped knife is commonly used for sectioning large or hard specimens.
t
OOO: Knife sharpening stone in honing
A) Carborundum
B) Belgian yellow
C) Glassplate
D) Rubber
D
process of polishing the cutting edge of a knife after honing is called __________
stropping
T/F Honing is done in a heel-to-toe direction, while stropping is done in a toe-to-heel direction
T
T/F Stropping is done in a heel-to-toe direction, just like honing
F - toe-to-heel, opposite to honing.
Select: Angles related to microtome knives
A) Bevel Angle
B) Rake Angle
C) Clearance Angle
D) Depth Angle
A B C
angle formed by the intersection of two planes, the cutting facets of the knife
bevel angle
specific angle range of bevel angle
27-32 degrees
specific angle range of clearance angle
5-10 degrees
straight line formed by intersection
of 2 planes, the cutting facets
cutting edge
The recommended width of the facets that form the cutting edge of a microtome knife is between ______ and ____ mm
0.1-0.6 mm
A __________ rake angle results in a cutting action, while a negative rake angle results in a scraping action.
+
T/F the smaller the bevel angle, the more likely it is that the knife will maintain its sharpness for a longer period.
F - smaller bevel angle sharpens the knife, but may cause quicker wear and elastic distortion
angle formed between the surface of the block and the cutting facet of the knife
clearance angle
T/F clearance angle ensures that the entire knife blade is in contact with the specimen block for smoother cuts
F– only cutting edge of the knife should touch the specimen block; too much contact causes knife chatter.
T/F setting the optimal blade clearance angle is important for achieving precise cuts and preventing knife chatter
t
T/F bevel angle of a microtome knife is typically between 27° to 32°
t
T/F wedge angle is responsible for determining how deeply the knife penetrates into the tissue block
f - wedge angle does not determine depth; it helps maintain the sharpness and durability of the blade
angle between upper surface of
cutting facet and the surface of the
block
rake angle
angle between the sides of the knives + what specific angle measurement
wedge angle; 0.15 deg
t/f blade should pass through the mucosa first when orienting an intestinal specimen
f - last
in skin tissue, blade should pass through the ____ last during sectioning
epidermis
when sectioning the cervix, it is better to present a point of __________ to the blade rather than a straight edge
dense tissue
extremely sharp knife design but are also very delicate and are therefore only used with very soft samples
planar concave
t/f chisel profile knife designs are more stable and find use in moderately hard materials, such as in epoxy or cryogenic sample cutting
f - wedge profile knives
_______ knife design raises the stability of the knife while requiring more force to achieve the cut due to its blunt edge
chisel profile
knife profile that has concavity on both sides and is less rigid, making it prone to vibration
Profile B: Biconcave Knife
T/F profile B, the biconcave knife, is recommended for cutting paraffin-embedded sections on a rotary microtome
t
knife profile known as the standard knife profile and is used for sectioning formalin-fixed paraffin-embedded (FFPE) tissues
profile c: wedge knife
t/f vertical scratches in sections can occur due to the specimen being excessively dehydrated.
f - vertical scratches are caused by defects in the blade edge, calcium, bone, or hard material in the specimen
t/f profile a, the plano-concave knife, is typically used on all types of microtomes for sectioning all types of tissues.
f - wedge knife (Profile C)
Select: least rigid and prone to vibration
A) Plano-concave
B) Biconcave
C) Wedge
B
knife profile used for cutting celloidin sections and has lesser concavity for this purpose
Profile A: Plano-Concave Knife
t/f profile a produces the sharpest edge and is used on sliding, rotary, and rocking microtomes.
t
knife profile most commonly utilized steel knife for routine histopathology and has flat cutting surfaces
profile c: wedge knife
usual length of a biconcave knife (Profile B)
100-250 mm
t/f profile C, the wedge knife, can be sharpened as much as Profile A
f - wedge knife cannot be ground as sharp as Profile A
to prevent thick sections in microtomy, you should adjust the _______
thickness
holes in the section can be prevented by ensuring to _______ the block with ice before cutting.
chill
