trimming and sectioning Flashcards
Removal of excess wax using knife or cutter after
the wax block is removed from the tissue cassette or
paper boat
TRIMMING
There is a formation of a ____________and
exposure of the tissue surface for ease of sectioning
truncated pyramid
types of trimming
> coarse trimming - large tissue
fine trimming - small tissue
microtomy is also known as
Sectioning
Spring-balanced or pawl is brought into
contact with, and turns a ratchet feed wheel
connected to a micrometer screw, which is in
turn rotated, moving the tissue block at a predetermined distance towards the knife for
cutting sections at uniform thickness.
MICROTOMY
Essential Parts: of microtome
- Block Holder
- Knife Carrier and Knife
- Pawl, Ratchet Feed Wheel and
Adjustment Screws
> Simplest form of microtome
Invented by: Paldwell Trefall (1881)
10-12 μm thickness (tissues are cut in slightly curved
planes thus not recommended for serial sections)
Heavy base, 2 arms
ROCKING MICROTOME (CAMBRIDGE)
resting on pivots and
supporting medium, attached to the
micrometer screw.
Lower arm
carrying the block holder on
one end by means of a screw, is connected
to a lever by a piece of nylon thread.
Upper arm
● Most common
● Used for routine and research laboratories
● Media: Paraffin
● Excellent for serial sections
● Invented by: Minot (1885-86)
● Electrically driven is now available
● Knife and block holder are brought together by
upward and vertical motions, cutting sections in a
perfectly flat plane.
● Relatively dangerous; because it utilizes disposable
blades, which are sharper compared to the traditional
microtome knives.
ROTARY MICROTOME (MINOT)
● Developed by: Adams (1789)
● Recommended for cutting “extremely” hard and
rough tissue blocks.
SLIDING MICROTOME
electrically driven
and ideal for resin-embedded decalcified
bone.
Base-Sledge Microtome
knife is
moving (Most dangerous type of microtome)
Standard Sliding Microtome
● Invented by: Quickett (1848)
● Stage for block holder: Hollow and Perforated,
attached to a flexible lead pipe containing carbon
dioxide.
● Carbon dioxide - freezing agent
● This type of microtome is firmly attached on the edge
of the bench.
Used to cut undehydrated tissues in a frozen state
FREEZING MICROTOME
● More common than freezing microtome
● Used for rapid preparation of urgent tissue biopsies
for intraoperative diagnosis (STAT); STATIM or rapid
turnaround time
● It consists of microtome - Rotary Microtome - kept
inside a cold chamber
● Chamber: -5 to -30°C; Average: -20°C
● Thermostat: capable of freezing fresh tissue within
2-3 minutes
● Cutting Section: 4 μm
● All the controls to the microtome are operated from
the outside the refrigerated cabinet
● Testing: Fluorescent antibody staining technique or
histochemical enzyme studies
CRYOSTAT OR COLD MICROTOME
