Quiz 2 Flashcards
- The block remains stationary while the knife is moved backward and forward during the process of sectioning.
- Developed mainly for cutting celloidin-embedded tissue blocks
- Inherently more dangerous
Standard sliding microtome
- Invented by Queckett in 1848
- The stage for block holder is hollow and perforated around its perimeter, attached to a reinforced flexible lead pipe thru which carbon dioxide passes from a cylinder.
Freezing Microtome
*A simple lever operated valve allows the release of rapid intermittent burst of carbon dioxide.
*A second cooling device for lowering temperature of the knife to facilitate sectioning.
Freezing Microtome
*Indications:
* Used to cut undehydrated tissues in a frozen state
* When histological demonstration of fat is needed
* When certain neurological structures are to be studied
* When sensitive tissue constituents to be studied are
damaged or destroyed by heat.
Freezing Microtome
- Consists of microtome kept inside a
cold chamber which has been
maintained at a temperature
between -5 to -30°C (-20°C) by an
adjustable thermostat - Capable of freezing fresh tissues
within 2-3 minutes - Can cut sections of 4µ with ease.
Cryostat
- Provides a means of preparing thin
sections of fresh frozen tissues for
fluorescent antibody staining
techniques or histochemical
enzyme studies. - Most commonly used for rapid
preparation of urgent tissue
biopsies for intraoperative
diagnosis.
Cryostat
are used to mount tissues in the Cryotome
OCT
- Primarily used for cutting tissue sections at 0.5 micra for
electron microscopy. - The knife used for cutting the ultrathin sections consists mainly of selected fragments of broken plate glass.
- The specimen used is small, fixed in osmium tetroxide, and embedded in plastic.
Ultrathin Microtome
Kinds of Microtome
- Vibrating Microtome
- Hand Microtome
- Saw Microtome
- Laser Microtome
- Computerized Microtome
Care of the Microtome
All the accumulated paraffin and small pieces of tissues must be brushed away with soft brush and not allowed to stay in the microtome
True
Care of the Microtome
After drying the machine and knife holder, the parts should be wiped with xylol
True
Care of the Microtome
Microtome must always be covered
when not in use.
True
Care of the Microtome
Movable portions should be oiled
thoroughly to prevent rusting
True
Types of Microtome Knives
- Usually 25 mm in length
- One side of the knife is flat while the other is concave.
Plane-concave knife
Types of Microtome Knives
- Usually 120 mm in length
*With both sides concave, recommended for cutting paraffin embedded sections on a rotary microtome.
Biconcave knife
Microtome Knives
- Usually 100 mm in length
- Have both sides straight
- Recommended for frozen sections or for cutting extremely hard and tough specimens embedded in paraffin blocks using a base-sledge type or sliding mircrotome.
Plane-wedge knife
Microtome Knives
- Have a sharp cutting edge that can cut 2-4 µ thick sections with ease.
- Cheaper to use
Disposable Blades
Microtome Knives
Used for trimming and semi-thin sectioning of tissue blocks for electron microscopy.
* Commercially prepared
* Should be prepared and stored in dust-free boxes with lids, just before use, to avoid contamination.
Glass Knives
Microtome Knives
- Used to cut any type of resin block for electron microscopy
- Are brittle and expensive, but very durable
- They are already mounted in a metal block designed to fit directly into the knife holder of the ultrathin microtome when purchased.
Diamond Knives
Other Equipment For Tissue Sectioning
- Temperature: About 10°C below the melting point of the paraffin wax.
- A small amount of detergent may be added to water to reduce surface tension and allow section to flatten out.
Floatation Water Bath
Other Equipment For Tissue Sectioning
- Temperature is set at the melting point of the wax,to 2-5 degrees Celsius above* (*Gregorio’s)
Drying oven or hot plate
Other Equipment For Tissue Sectioning
- Both are needed for handling sections during cutting and removing folds and creases during “floating out” in waterbath.
Forceps and squirrel/camel hairbrush
Other Equipment For Tissue Sectioning
Clean slides and Coverslips
