sectioning Flashcards by MJ M

process of cutting tissues into uniformly thin slices for microscope studies

sectioning

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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)

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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

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Select: General types of tissue sections

A) Paraffin Sections
B) Celloidin Sections
C) Frozen Sections
D) Rubberized Sections

A B C

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rocking and rotary microtomes can create ____ sections

paraffin sections

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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

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material commonly used in frozen sections for cutting fresh or fixed tissues in a cryostat

CO2

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cut from tissues that have been fixed and frozen w/ CO2 or for fresh or fixed tissues frozen w/ the cryostat

frozen sections

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t/f microtome knives can use blades made of steel, glass, or diamond depending on the specimen and desired thickness

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OOO: Type of microtome knife

A) Standard Steel Blade
B) Glass Knife
C) Carbon Blade
D) Diamond Knife

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Coarse trimming of paraffin blocks is done until about _____ mm of wax remains on all sides of the tissue.

2 mm

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T/F when trimming blocks, attempting to trim large pieces of wax can lead to splitting and exposure of tissue

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term used for removing wax until the tissue surface is exposed, done at approximately 30 microns at a time

coarse trimming (facing)

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fine trimming is done by setting the thickness adjuster to _____ microns, trimming away the surface block until the tissue is partly exposed.

15 microns

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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

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microtome knife profile shaped with a concave side on both planes

biconcave

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T/F a chisel-shaped knife is commonly used for sectioning large or hard specimens.

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OOO: Knife sharpening stone in honing

A) Carborundum
B) Belgian yellow
C) Glassplate
D) Rubber

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process of polishing the cutting edge of a knife after honing is called __________

stropping

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T/F Honing is done in a heel-to-toe direction, while stropping is done in a toe-to-heel direction

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T/F Stropping is done in a heel-to-toe direction, just like honing

F - toe-to-heel, opposite to honing.

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Select: Angles related to microtome knives

A) Bevel Angle
B) Rake Angle
C) Clearance Angle
D) Depth Angle

A B C

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angle formed by the intersection of two planes, the cutting facets of the knife

bevel angle

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specific angle range of bevel angle

27-32 degrees

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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/F bevel angle of a microtome knife is typically between 27° to 32°

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

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

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.

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

Select: Prevent washboarding or undulation in sections A) Proper clamping of blade and block B) Overextending the block holder shaft C) Ensuring the microtome is in good working order D) Decreasing the blade tilt

A C D

knife profile recommended for paraffin sections and has more concavity for this purpose

profile a: plano-concave knife

OOO: vertical scratches A) Defect in blade edge B) Calcium in specimen C) Aggressive block facing D) Bone in the specimen

issue in microtomy that commonly occurs in very hard or over-fixed tissue and causes a macroscopic type of chatter

washboarding / undulation

t/f holes in the section can occur when the block is faced too aggressively

t/f crooked ribbons result when the upper and lower edges of the block are parallel.

f - crooked ribbons occur when the horizontal edges of the block are NOT parallel

block-face unevenly sectioned happens when the _______ is not parallel to the blade.

block holder

ooo: prevention method for failure of ribbon to form A) Using paraffin with a lower melting point B) Decreasing the blade tilt C) Using a dull blade D) Changing room temperature

to prevent this issue, the upper and lower edges should be parallel and the lower block edge must be parallel to the knife edge

crooked ribbons

issue is caused by sections being too thick, or the surfaces and edges of the block not being parallel

failure of ribbon to form

CNS tissues are more likely to _______ from the slide when sections are being prepared

float

Sequence: Prevent holes in the section A) Chill block with ice B) Face block less aggressively C) Discard ribbons until hole disappears

a c b

to prevent crooked ribbons, ensure that the _______ block edge is parallel to the knife edge

lower

Select: Sections are likely to float off the slide A) Cryostat sections for urgent diagnosis B) Tissues from the CNS C) Tissues decalcified with strong acids D) Sections in strong acidic solutions

a b c

t/f failure of a ribbon to form is often caused by sections being too thick and using a dull blade

OOO: sections are likely to float A) When sections are submitted to high temperatures B) When sections are exposed to acidic solutions C) When sections contain blood clots D) Cryostat sections for immunofluorescence

primary purpose of applying adhesives to slides in microtomy

promote adhesion of sections to the slide

t/f sections are less likely to float from the slide when exposed to strong alkali solutions during staining

f - sections are more likely to float from the slide in strong alkali solutions

t/f Tissues that have been decalcified are less likely to float from the slide during sectioning

f - more likely

adhesives help sections stay on the slide, especially when the sections are submitted to _______ during staining

high temperatures

component added to increase viscosity and prevent complete drying in albumin adhesives

glycerol

sections particularly prone to floating off the slide in procedures like immunofluorescence or immunocytochemistry

Cryostat sections

substance added to Meyer’s Egg Albumin to inhibit mold growth

Thymol crystal

background staining in albumin adhesives may be detected due to its uptake of _______.

DYES

t/f preservatives are not required in albumin-based adhesives because they naturally resist decomposition.

f - added to prevent putrefaction

albumin from ______, ______, and human plasma can be used as tissue adhesives.

eggs, bovine

t/f Gelatin must be heated gently before use to melt and shouldn't be kept molten for long periods

OOO: source of albumin in tissue adhesives A) Egg B) Bovine C) Human plasma D) Synthetic polymers

Select: prone to staining with many dyes A) Gelatin B) Starch C) Cellulose D) Poly-L-Lysine

t/f Poly-L-Lysine causes background staining.

f - does not

Poly-L-Lysine is commonly used to improve section adhesion, particularly in ________.

immunocytochemistry

adhesive that provides firmer attachment than albumin and is added to the flotation water bath

Gelatin

t/f resins provide the greatest adhesion and are resistant to most fluids used in section treatments.

adhesive known for its strong adhesive properties but can blacken in some silver impregnation techniques

Sodium Silicate

select: adhesives cause minimal background staining A) Sodium Silicate B) Albumin C) Poly-L-Lysine D) APES

C D

_____ is a new advance in section adhesion that can withstand repeated washings with various inorganic solvents

APES (3-Aminopropyltriethoxysilane)

OOO: background staining A) APES B) Poly-L-Lysine C) Sodium Silicate D) Albumin

What does APES stand for in tissue adhesives

3-Aminopropyltriethoxysilane

What ensures that APES-treated (silanized) slides' positive charge cannot be washed away, unlike Poly-L-Lysine

Covalent bonding to the glass

what tool can be used to remove bubbles from the water bath during tissue sectioning

Teasing needle or applicator stick

t/f Tissue sections must be placed in the water bath for at least 2 minutes to avoid undue expansion and distortion.

f - max 30 secs to avoid distortion

t/f purpose of the initial deparaffinization is to completely remove the paraffin wax from the tissue

f - only partial; full deparaffinization occurs during xylene staining

OOO: fishing-out process A) Gelatin USP dissolved in the water bath B) Slide with tissue adhesive C) Centrifuge D) Hot plate or paraffin oven

The floatation water bath temperature should be around ___ to ___°C for optimal tissue sectioning.

40-50°C.

Sequence: fishing out tissue sections: A) Immerse the slide vertically B) Gently lift the slide vertically C) Dry the section in a hot plate or paraffin oven D) Fish out the section

A D B C

temperature for initial deparaffinization on the hot plate or paraffin oven is set at __°C for 20 minutes

70C

Select: fish out tissue sections from the water bath A) Slide lightly smeared with tissue adhesive B) Smooth teasing needle C) Hot air oven D) Plastic applicator

sectioning Flashcards

(138 cards)