SECTIONING Flashcards
embedded tissue is trimmed and cut into uniformly thin slices using a microtome
sectioning
3 essential parts of microtome
- block holder (aka chuck)
- knife carrier and knife
- pawl, ratchet feed wheel and adjustment screws
inventor of rocking microtome
paldwell trefall
simplest and most popular type
rocking microtome
routinely used microtome
rotary microtome
inventor of rotary microtome
Minot
for celloidin sections and hard rough tissue blocks
sliding microtome
inventor of sliding microtome
Adams
two types of sliding microtome
base sledge/sledge type and standard sliding
for frozen sections; CO2 is used as a propellant
Freezing Microtome
invented by Quackelt
freezing microtome
what is inside of a cryostat/cold microtome
rotary microtome
microtome primarily for electron microscopy
ultrathin microtome
special knife used in ultrathin microtome
diamond knife
for enzyme histochem
vibratome
very hard material (undecalcified bone); tissue embedded in resins
saw microtome
25 mm
plane concave
120 mm
biconcave knife
knife used for rotary microtome
biconcave knife
used for rocking microtomes with a fixed handle
Heiffor Knife
100 mm
plane wedge
for frozen sections or very hard tissues
plane wedge
knives for ultrathin microtome
glass and diamond knives
found on the tapered edge of a knife
bevel
angle formed between the cutting edge
bevel angle
optimum angle for cutting angle
15 degrees
angle formed between the surface of the block and the cutting edge of the knife; 0.15 degrees
clearance angle
angle of the upper surface of the facet and surface of tissue block
rake angle
angle between the sides of knife
wedge angle
process of removing nicks (irregularities of knife)
Honing
movement of Honing
from HEEL TO TOE
number of strokes per surface
10-20 strokes
hones for best result
belgium yellow
hones with polishing effects
arkansas
hones for badly nicked
fine carborundum
used for removal of burrs (irregularities of knife formed after honing)
stropping
movement from top to heel
stropping
paddle strop is made of
hoarse leather
rapid diagnosis; for enzyme histochemistry
frozen section
point in which sections may be cut at 10 um; frozen tissue starts to thaw (warmed with the finger) and becomes invisible to the naked eye
dew line
used to remove the ribbon that sticks to the knife blade
camel hairbrush
optimum temp of cryostat
-18 to -20C (20C)
most rapid method of freezing
liquid nitrogen
not for muscle; made of fluorinated hydrocarbons
aerosol sprays
methods of freezing
- liquid nitrogen
- isopentane
- aerosol sprays
- carbon dioxide
- freon
clearing agents used in frozen section
glycerin and gum syrup (water soluble)
use of synthetic water soluble glycols and resins
mounting
recommended mounting medium
OCT (optimal cutting temperature compound)
difficulties due to faulty fixation, dehydration, clearing, embedding
- brittle; hard tissue
- clearing agent becomes milky
- soft and mushy tissue
- tissue becomes opaque
- very hard tissues; tissue shrinkage
- air holes on trimmed tissue block
- moist block that tends to crumble
tissue block smells like xylene
horizontal or parallel lines across the sections
chatters
most common tissue adhesive
mayer’s egg albumin
components of mayer’s egg albumin
- egg white
- glycerol
- thymol crystals
added to increase viscosity and prevent complete drying
glycerol
used as a general purpose section adhesive
poly-L-lysine
widely used as an adhesive in immunohistochem
poly-L-lysine
stops the chemical reaction and diffusion in tissue
quenching
most time consuming; introduction of heat to cause sublimation of heat; removal of water vapor from surface of specimen
drying
freezing substitution makes use of ___________
rossman’s formula or in 1% acetone and dehydrated in absolute alcohol
