Manual - Instrumentation in Histotechnology Flashcards
The earliest form of microtomy was the freehand sectioning of fresh or fixed material using a
sharp razor
are precision instruments
designed to cut uniformly thin sections of a variety of material for detailed microscopic examination.
Modern microtomes
Parts of a microtome
Block holder
Knife stand/holder
Thickness scale
flywheel
Knife stand clamp
Knife
- This type of microtome is generally used for cutting semi-thin to thin sections
of paraffin wax embedded material for light microscopy.
Rotary Microtome
Rotary Microtome
Paraffin embedded tissues are normally cut between_______
3 to 5 µm
The operation of the microtome is based upon the rotary action of a hand wheel activating
the advancement of a block towards a rigidly held knife.
The block moves up and down in a vertical plane in relation to the knife and therefore it cuts flat sections.
Rotary microtome
The knife holding clamps allow the knife to be offset to one direction, a major advantage
when sectioning large, hard blocks.
They are not suitable for cutting very hard resins such as araldite because of the risk of vibration
Sliding Microtome
- These are designed for cutting large blocks of paraffin and resin embedded
material including whole organs, for light microscopy.
Sliding Microtome
The rocking
microtome was invented by _______(1851-1928), the son of
Charles Darwin.
Sir Horace Darwin
- The razor of this microtome is fixed and the specimen to be sliced for microscopic examination passes up and down in an arc of a circle across the razor in a rocking motion.
Fixed on to a table, the ribbons of specimen
fell to the desk top then were cut and mounted on to slides.
Rocking Microtome
Freezing Microtome
* This form of microtome is used for cutting thin to semi-thin (about _______)
sections of fresh, frozen tissue.
8-12µm
is equipped with a stage upon which tissue can be quickly frozen using either liquid carbon dioxide, from a cylinder, or a low temperature recirculating coolant.
Some cooling systems also allow the knife to be cooled at the same time. The
cutting action of the freezing microtome differs from those described
previously as in this case the knife is moved while the tissue block remains
static.
Consistent, high quality, thin sections are very difficult to obtain with
this type of microtome.
The freezing microtome
is primarily used for cutting sections of frozen tissue. It commonly consists of a microtome contained within a refrigerated chamber, the temperature of which can be maintained at a preset level.
Cryostat
The cryostat usually contains a _______ microtome although some portable units utilize a rocking microtome.
With the block, blockholder and knife all at the same temperature and all other conditions for
cutting the material optimal, sections as thin as _____ are possible.
rotary
1 micron
- It is used to prepare ultrathin sections for light and electron microscopy. Very small samples of tissue are usually embedded in hard resin before cutting.
Ultrathin microtome
The cutting stroke is motor driven to provide a regular, smooth motion for sections of even thickness and constant reproducibility.
ultrathin microtome
Ultrathin microtome
Knives are usually made from (3)
The block is brought to the knife edge under microscopic control and as each section is cut it is floated on to a water bath adjacent to the knife edge.
glass, diamond or sapphire
- These are used for floating the paraffin ribbon.
FLOTATION BATH OR WATER BATH
Water BATH
Temperature depends on a degree of the personal preference of the microtomist, but it is recommended to maintain a temperature of ______ degrees below the melting point of the
paraffin used during embedding.
5 to10
These are used for drying the water that is
collected during the sectioning of tissue section.
Slide dryers
Water Bath
The temperature used is between _____
degrees above the melting point of the paraffin.
5 - 10
Water Bath
Slides are left to dry for approximately _____
minutes, after they have been appropriately
drained.
Not doing so can cause the bubbling
under the tissue sections.
Overheating slides may cause uneven staining as well as artifacts
15-20
is used to heat and speed some procedures. Some special stains techniques are performed in the ________.
MICROWAVE OVEN
- It is a complete system designed for
embedding tissue in paraffin.
It provides a controlled heated environment (paraffin is kept at _________ above its melting point) for the processed cassettes and eliminates xylene contamination.
Embedding Centers
2 - 4ºC
transfer slides from one container to the next container with the same time allowed in each container.
_______ are similar to the linear stainer and the time allowed in each can be varied.
_______ are flexible with computerized programming that allows the
continuous loading and use of the same solutions at different timing.
AUTOMATED STAINERS
Linear types
Revolving types
Robotic ones
- Maintains the paraffin wax in liquid form and aids in dispensing of wax into molds or casts.
PARAFFIN WAX DISPENSER
