TRIMMING AND MICROTOMY Flashcards
trans based
Expected output after embedding
Tissue block
Purpose of trimming
To even out the edges of our tissue block
Removal of excess wax using a knife or cutter after the wax block is removed from the tissue cassette
or paper boat
trimming
ideal shape for trimming
truncated pyramid
2 types of trimming
coarse trimming
fine trimming
a.k.a sectioning
microtomy
what is the result for microtomy?
tissue ribbons
an indication that your sectioning is correct and you already cut thin slices of tissues which are ready to be transferred to the flotation bath.
tissue ribbons
Sections usually form ribbons due to … generated between the block and the knife edge during the process of cutting.
slight heat
Complete ribbons are picked up and transferred to a flotation bath with a
camel hair brush
forceps
fingers
To ensure the measurement or
thickness of tissue sections.
Pawl, Ratchet Feed Wheel, and
Adjustment Screws
essential parts of microtome
Block Holder
Knife Carrier and Knife
Pawl, Ratchet Feed Wheel, and
Adjustment Screws
To hold the tissue block
Block Holder
To do the actual cutting or
sectioning of the tissues.
Knife Carrier and Knife
simplest microtome invented by paldwell trefall
rocking microtome
thickness of tissues produced by the rocking microtome
10-12um
most common microtome that is used for routine and research laboratories and is invented by Minot
rotary microtome
media used in rotary microtome
paraffin
thickness of tissues produced by rotary microtome
3-5um
microtome that is excellent for serial sections
rotary microtome
microtome developed by adams
sliding microtome
Recommended for cutting “extremely” hard and rough tissue blocks. Cannot make tissue ribbons, only tissue sections.
sliding microtome
types of sliding microtome
Base-Sledge Microtome
Standard Sliding Microtome
microtome invented by quickett and is ideal for fresh tissues that did not undergo fixation down to infiltration
freezing microtome
freezing agent of freezing microtome
carbon dioxide
More common than freezing microtome. Used for rapid preparation of urgent tissue biopsies
for intraoperative diagnosis
cryostat or cold microtome
temp of chamber of cryostat
-5 to -30 degrees
average temp for cryostat
-20 degrees
how many minutes does the cryostat capable of freezing a fresh tissue
2-3 minutes
thickness of section can a cryostat can cut
4um
Fluorescent antibody staining technique or histochemical enzyme studies.
cryostat
cutting section of ultrathin microtome
0.5um
media used for ultrathin microtome
plastic
in ultrathin microtome if used in electron microscopy tissues must be fixed with …
osmic acid
may also be used for cleaning
some parts of the microtome.
xylene
types of tissue sections
paraffin
celloidin
frozen section
most common tissue section, Successive sections will usually stick
edge-to-edge. Sections are removed in ribbons of ten to allow easy location of serial sections.
paraffin
thickness of paraffin
4-6um
To avoid dehydration and shrinkage,
sections are usually cut by the wet method, with both the sections and the block being kept moist with 70% alcohol during cutting.
celloidin
thickness of celloidin
10-15um
widely used blade because it is cheap and coated with polytetrafluoroethylene and only used for 10 tissue blocks only
disposable blade
blade used for ultrathin microtomes
glass knive/ralph knives
For resin blocks on ultrathin
microtomes; Brittle and expensive
diamond knives
Angle between the upper facet of the knife and the surface of the tissue block.
cutting angle: 14 degrees
For partially calcified materials,
paraffin, and frozen sections.
Safety Razor Blades
Angle of the knife itself and between the cutting edges
bevel angle: 27-32 degrees
Most important angle between the lower facet of the knife and the surface of the tissue block
clearing angle: 5-10 degrees
Removing of gross nicks
To acquire an even edge
HEEL to TOE
HONING
Removal of burr/irregularities
Final polishing of the knife
edge
TOE to HEEL
STROPPING
most common sharpening stone
belgium yellow
sharpening stone that has more polishing effect
Arkansas
sharpening stone that is coarser; for badly nicked knives
Fine Carborundum
sharpening stone that is excellent
Plate Glass
Used for adhesion of the tissue to be examined to the slide.
adhesives
most common adhesive
meyer’s egg albumin
increases viscosity and prevents drying
glycerol
prevents mold formation
thymol crystals
Better adhesion than albumin
1% Gelatin
Does not retain the stain.
1% Methyl Cellulose
No background staining
Poly-L Lysine
Strong adhesive;Slight dye retention, not affected by mild alkaline solutions 3 months.
Disadvantage: Blackening in silver
impregnation staining, reticulin methods, red staining in methyl green pyronin technique.
Sodium silicate
Diluted 1:10 with acetone; Has the greatest adhesion
Resins
Sections are floated out on a water bath set at what temp
45-50°C
