CHAPTER 12: MICROTOMY Flashcards
The process by which processed tissue, most commonly a paraffin embedded tissue, is trimmed and cut into uniformly thin slices or “sections”
Microtomy
This process is done to facilitate studies under the microscope
Microtomy
The basic instrument used in microtomy
microtome
It is capable of cutting a section at a predetermined thickness by sliding the block into a cutting tool
Microtomy
How is a microtome used?
- by sliding the block into a cutting tool
- usually a steel knife, glass or diamond blade which is fixed and attached to the machine
What are the 3 essential parts of a microtome?
BPK
- Block holder
- Pawl, Ratchet Feed wheel and Adjustment Screws
- Knife carrier and knife
What are the 3 essential parts of a microtome?
BPK
- Block holder
- Pawl, Ratchet Feed wheel and Adjustment Screws
- Knife carrier and knife
This is the part of the microtome where the tissue is held in position
Block holder
This is the part of the microtome for actual cutting of tissue sections
Knife carrier and knife
This is the part of the microtome to line up the tissue block in proper position with the knife, adjusting the proper thickness of the tissue for successive sections
Pawl, Ratchet Feed Wheel and Adjustment Screws
This is the part of the microtome to line up the tissue block in proper position with the knife, adjusting the proper thickness of the tissue for successive sections
Pawl, Ratchet Feed Wheel and Adjustment Screws
Whatever the type of microtome is used, what is the principle that remains essentially the same?
- a spring-balanced teeth 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 toward the knife
- for cutting sections at uniform thickness
What are the 5 kinds of microtomes?
RRUF CS
- Rocking microtome
- Rotary microtome
- Ultrathin microtome
- Cryostat/Cold microtome
- Sliding microtome
These microtome/s are used for cutting paraffin embedded tissues?
- Rotary microtome
- Rocking microtome
This microtome is used for cutting serial sections of large blocks of paraffin embedded tissues
Rocking microtome
Used for cutting paraffin embedded sections
Rotary microtome
Used for cutting celloidin embedded sections
Sliding microtome
Used for cutting unembedded frozen sections
Freezing microtome
Used for cutting frozen sections
Cryostat/Cold microtome
Used for cutting section for Electron Microscopy
Ultrathin microtome
Another name for rocking microtome
Cambridge microtome
Another term for rotary microtome
Minot microtome
Who invented the Rocking (Cambridge) microtome?
Paldwell Trefall
When was the Rocking (Cambridge) microtome invented?
1881
This microtome is the simplest among the different types of microtomes
Rocking microtome
This microtome consists of a heavy base and two arms
Rocking microtome
Which arm of the rocking microtome rests on pivots and a supporting column?
The lower arm
The lower arm of the rocking microtome rests on what?
rests on pivots and a supporting column
The pivots and the supporting column of the lower arm of the rocking microtome is attached to the what?
attached to the micrometer screw
The lower arm is found at the base
true or false
TRUE
Where is the racthet wheel with the feed mechanism of the rocking microtome found?
at the base
Which arm of the rocking microtome is connected to a lever by a piece of nylon thread?
Upper arm
Which arm of the rocking microtome carries the block holder on one end by means of a screw?
Upper arm
The upper arm of the rocking microtome carries the block holder on one end by means of a what?
means of a screw
The upper arm is connected to a what?
connected to a lever
The upper arm is connected to a lever by what?
connected to a lever by a piece of nylon thread
When the lever of the rocking microtome is pulled backward, the pawl is brought in contact with the ratchet wheel
true or false
When the lever is pulled forward
FALSE
When the lever of the rocking microtome is pulled forward, what is brought in contact with the ratchet wheel?
Pawl
Specifically, the millhead micrometer scre is attached to what?
ratchet wheel
The lower arm of the rocking microtome is elevated, which in turn raises the upper arm at its fulcrum
True or False
TRUE
What happens when the lower arm of the rocking microtome is elevated?
carries the the chuck or block holder forward, towards the knife
This causes the upper arm to return to its normal position
tension on the spring
What causes tension on the spring of the rocking microtome?
As the pressure on the operating handle or lever is released
What is the normal position of the upper arm of the rocking microtome?
an arc of a circle
A section is thereby cut as the tissue passes to the knife edge in a slightly curved plane
True or False
TRUE
A section is thereby cut as the tissue passes to the knife edge in a slightly curved plane, in how thick?
10-12 u thickness
This microtome is available in two sizes
Cambridge rocking microtome
This microtome has been used to cut small and LARGE blocks of paraffin blocks?
Cambridge rocking microtome
This microtome is theoretically NOT recommended for serial sections
Cambridge rocking microtome
Why is the cambridge rocking microtome not recommended for serial sections?
since tissues are cut in SLIGHTLY CURVES PLANES
This kind of microtome is NOT currently favored by most laboratories
Cambridge rocking microtome
What are the 2 reasons why the Cambridge rocking microtome not currently favours by most laboratories?
- Because of the restrictions in size of tissue block that CAN be cut
- The difficulty of reorienting the block
Who invented the rotary microtome?
Minot
When was the rotary microtome invented?
1885-1886
This microtome is used to cut paraffin embedded tissues
Rotary microtome
This microtome is currently the MOST COMMON type used for BOTH routine and research laboratories
Rotary microtome
This microtome is the most common type used especially for sectioning paraffin-embedded tissues
Rotary microtome
These microtomes are now available and can be IDEALLY used to produce RIBBONS for SERIAL SECTIONS
Electrically driven rotary microtomes
The device operates with a staged rotary action such that the actual cutting is part of the rotary motion
Rotary microtome
In a rotary microtome, the knife is fixed in what position?
in a horizontal position
In rotary microtomes, although the flywheel in many microtomes can be operated manually, they are generally automated or semi-automated.
True or False
TRUE
In rotary microtomes, how are section typically cut?
between 3 and 5 um
Typically, sections are cut between 3 and 5 um using what?
using paraffin wax
Typically, sections are cut between 3 and 5 um using what?
using paraffin wax
This microtome is used for diagnostic histology
Rotary microtome
In rotary microtome, thinner sections can be attained if samples are embedded in what?
embedded in synthetic resin
In rotary microtome, thicker sections can be attained if samples are embedded in synthetic resin
True or False
Thinner sections
FALSE
How is the Rotary microtome is different from rocking microtome?
the knife and the block holder are brought together by UPWARD and VERTICAL motions
The knife and the block holder of the Rotary microtome are brought together by what motions?
upward and vertical motions
The knife and the block holder of the rotary microtome are brought together by upward and vertical motions, cutting sections in a perfectly flat plane
TRUE OR FALSE
TRUE
These microtomes allow excellent serial sections to be cut
- rotary microtome
- sliding microtome
This microtome is heavier than the rocking microtome
rotary microtome
This microtome is more complex in design and construction, and is therefore more expensive
Rotary microtome
Sliding microtomes may be used for cutting large blocks of tissues although results are better when the rotary microtome is used
TRUE OR FALSE
Better results when the sliding microtome is used
FALSE
Sliding microtomes may be used for cutting large blocks of tissues although results are better when the rotary microtome is used
TRUE OR FALSE
Better results when the sliding microtome is used
FALSE
Rotary microtomes may be used for cutting large blocks
true or false
TRUE
The knife of the rotary microtome is placed in a what?
placed in a blade-up position
The knife of the rotary microtome is placed in a what?
placed in a blade-up position
Rotary microtome is relatively dangerous because the knife is placed in a bladed-up position
true or false
TRUE
Both manual and electrically driven models are now available for cutting what?
for cutting ultrathin sections and for cryostat use
This microtome uses a heavier knife
Rotary microtome
This microtome has less vibrations
Rotary microtome
Why are there less vibrations for rotary microtome?
because a heavier knife is used
The cutting angle (tilt) of the knife is adjustable, so it can cut harder tissue. What is microtome?
Rotary microtome
Rotary microtomes cannot cut celloidin-embedded sections
True or false
can cut celloidin-embedded sections
FALSE
Rotary microtomes cannot cut celloidin-embedded sections
True or false
can cut celloidin-embedded sections
FALSE
Rotary microtomes can cut celloidin-embedded section by using a what?
by using a special holder
In rotary microtomes, what is the use of the special holder in cutting celloidin-embedded sections?
to set the knife obliquely
In rotary microtomes, what is the use of the special holder in cutting celloidin-embedded sections?
to set the knife obliquely
What are the 2 types/models of the sliding microtome??
- Base-Sledge Microtome
- Standard Sliding microtome
What are the 2 types/models of the sliding microtome??
- Base-Sledge Microtome
- Standard Sliding microtome
When was the sliding microtome invented?
1789
Who invented the sliding microtome?
Adams
What type of sliding microtome consists of two movable pillars?
Base-Sledge microtome
The base-sledge microtome consists of two movable pillars that hold the adjustable knife clamps, allowing the nife to be set at an angle for cutting celloidin sections
True or False
TRUE
The chuck or block holder of the base-sledge microtome is set on a what?
on a heavy metal base
The chuck or block holder of the base-sledge microtome is set on a heavy metal base which can be moved backwards and forwards under the knife
true or false
TRUE
What type of sliding microtome is favored in laboratories where very hard tissue or large blocks are usually sectioned?
Base-sledge microtome
This is suited for sectioning specimens embedded in ALL FORMS OF MEDIA, especially for cutting section from tough tissue blocks which may offer great resistance to the knife
Base-Sledge microtome
In sliding microtomes, why are larger sections more easily cut with the knife that is set at an angle?
due to less resistance offered by the block
This microtome was originally designed for cutting sections of very large blocks (i.e., whole brain)
Base-Sledge microtome
These microtomes cut in a perfectly flat plane
- Sliding microtome (Base-sledge microtome
- rotary microtome
This microtome is comparatively heavier and more stable than the ordinary sliding microtome
Base-Sledge microtome
In Base-Sledge microtome, the angle of the knife is adjustable
true or false
TRUE
How long is the knife of a Base-Sledge microtome?
24 cm
The long knife of a base-Sledge microtome requires more honing
True or False
Less honing
FALSE
The long knife of a base-Sledge microtome requires more honing
True or False
Less honing
FALSE
What is the cutting angle of a rotary microtome?
tilted
What is the angle of the knife of a base-sledge microtome?
slanted
These microtomes under base-sledge microtomes are electrically driven
Modern models of heavy duty base sledge microtomes
These microtomes are ideal for resin-embedded decalcified bones
Modern models of heavy duty base-sledge microtomes
What is the difference between a base-sledge microtome and a standard sliding microtome?
- With a base sledge mirotome, the block can be moved backwards and forwards under the knife
- while with a standard sliding microtome, the block remains stationary while the knife is moved backward and forward
This type of sliding microtome was developed mainly for cutting celloidin-embedded tissue blocks
Standard sliding microtome
This type of sliding microtome is inherently MORE dangerous because of the movable knife, which makes it diffiicult to attach knife guards
Standard sliding microtome
Why is the Standard sliding microtome inherently MORE dangerous?
because of the movable knife
In both base-sledge microtome and standard sliding microtome, the knife can be set obliquely for large refractory paraffin blocks or straigh for celloidin sections
True or false
obliquely for celloidin sections; straight for large refractory paraffin blocks
FALSE
In both base-sledge microtome and standard sliding microtome, the knife can be set obliquely for large refractory paraffin blocks or straigh for celloidin sections
True or false
obliquely for celloidin sections; straight for large refractory paraffin blocks
FALSE
For both standard sliding microtome and base-sledige microtomes, how must the knife be set for cutting both large and small tissues with ease?
knife must be set straight
These microtomes are especially recommended for cutting EXTREMELY hard and r(t)ough tissue blocks
Sliding microtomes
It is the most dangerous type of microtome due to the movable exposed knife
Sliding microtome
A quick but very steady motion is required to manipulate the sliding microtome
True or false
A slow but very steady motion
FALSE
A quick but very steady motion is required to manipulate the sliding microtome
True or false
A slow but very steady motion
FALSE
Who invented the freezing microtome?
Queckett
When was the freezing microtome invented?
1848
The stage of a freezing microtome is hollow
TRUE OR FALSE
TRUE
A second cooling device for lowringhe temperature of the knife is also incorporated in most machines to facilitate sectioning in this type of microtome
Freezing microtome
It is used to cut undehydrated thin to semi-thin sections of fresh, frozen tissues
Freezing microtome
This type of microtome is especially used in instances when rapid diagnosis is required
Freezing microtome
This type of microtome is used when histological demonstration of fat is needed
Freezing microtome
This type of microtome is used when certain neurological structures are to be studied
Freezing microtome
This type of microtome is used when sensitive tissue constituents to be studied are damaged or destroyed by heat
freezing microtome
this microtome will give the best results and is used almost universally for cutting frozen sections
freezing microtome
This is equipped with stage upon which tissue can be quickly frozen using either liquid carbon dioxide, from a cylinder or a low temperature recirculating coolant.
freezing microtome
Why does the freezing microtome differ from other microtomes?
because the knife is moved whilst the tissue block remain static
This microtome is similar to the sliding microtome
freezing microtome
this microtome is similar to the freezing microtome
sliding microtome
this microtome is similar to the freezing microtome
sliding microtome
This is a refrigerated apparatus used for freezing tissue into the block holder to the correct degree of hardness that allows for easier and faster sectioning
Cryostat
What microtome is usually used in a cryostat or cold microtome?
rotary microtome
What microtome is usually used in a cryostat or cold microtome?
rotary microtome
this microtome consists of a microtome which is kept inside a cold chamber
cryostat or cold microtome
At what temperature must the cold chamber of the cryostat be maintained at?
-5 to -30 degC (average is -20 degC)
At what temperature must the cold chamber of the cryostat be maintained at?
-5 to -30 degC (average is -20 degC)
the cryostat is capable of freezing fres tissues within how many minutes?
2-3 minutes
What is the size of the section that a cryostat produces?
4 u
All controls in the cold microtome are operated from outside the refrigerated cabinet
true or false
true
This microtome provides a means of preparing thin sections of fresh frozen tissues especially for fluorescent antibody sharing techniques
Cryostat
This microtome is used for histochemical enzyme studies
cryostat or cold microtome
This microtome is commonly used for rapid preparation of urgent tissue biopsies for intraoperative diagnosis
cryostat
The cold microtome is often housed in the frozen section room close to the operating room to allow DIRECT CONSULTTION between who?
direct consultation between the surgeon and pathologist
Sections using a cryostat are usually transferred indirectly from the microtome knife to a slide or cover glass, all of which are maintained at a low temperature
True or false
transferred directly from the microtome knife to a slide or cover glass
false
Sections using a cryostat are usually transferred indirectly from the microtome knife to a slide or cover glass, all of which are maintained at a low temperature
True or false
transferred directly from the microtome knife to a slide or cover glass
false
this microtome is equipped with a glass or gem grade diamond knife
ultrathin microtome
this is used to cut very thin sections
ultrathin microtome
typically, ultrathin microtome produce what sizes of sections?
60 to 100 nanometers
the very thin sections of tissue in ultrathin microtomes are embedded in what?
embedded in epoxy resin
Section in ultrathin microtomes are stained with what?
stained with aqueous solution of an APPROPRIATE HEAVY METAL SALT
Sections from ultrathin mirotomes are examined using a what?
Transmission electron microscopy (TEM)
The ultrathin microtome also uses what materials to cut semi-thin sections prior to thin sectioning
uses a gladd knife or an industrial grade diamond knife
The ultrathin microtome is also used with a glass knife or an industrial grade diamond knife to cut thick sections after thick sectioning
true or false
to cut thin sections; prior to thin sectioning
false
The ultrathin microtome is also used with a glass knife or an industrial grade diamond knife to cut thick sections after thick sectioning
true or false
to cut semi-thin sections; prior to thin sectioning
false
The semi-thin sections produced in ultrathin microtomes are usually how thick?
0.5 to 1 um thick
semi-thin sections in ultrathin microtomes are mounted on a what?
mounted on a glass slide
To located areas of interest in ultrathin microtomes, sections are viewed under what microscope?
under a light microscope
semi-thin sections of a ultrathin microtome are viewed under a ight microscope after thin sectioning for the TEM
true or false
prior to thin sectioning
false
semi-thin sections of a ultrathin microtome are viewed under a ight microscope after thin sectioning for the TEM
true or false
prior to thin sectioning
false
Thin sectioning for the TEM is often done with a what?
with a gem quality diamond knife
Trimming and section-cutting are done with a what?
microtome knife
Trimming and section-cutting are done with a what?
microtome knife
What are the three basic types of microtome knives?
- Plane-concave knife
- biconcave knife
- Plane-wedge
how long is the measurement of a plane-concave knife?
25 mm in length
how long is the measurement of a biconcave knife?
120 mm in length
how long is the measurement of a plane-wedge knife?
100 mm in length
This knife is flat on one side while the other is concave
plane-concave knife
Less concave sides are recommended for cutting what kind of tissue blocks?
celloidin-embedded tissue blocks
Less concave sides cut celloidin-embedded tissue blocks on what microtome?
on a sliding microtome
More concave sides are used to cut what?
to cut paraffin sections
More concave sides are used to cut paraffin sections on a what?
- base sledge microtome (slidiing microtome)
- rotary microtome
- rocking microtome
this knife has have both concave sides
biconcave knife
This microtome knife is recommended for cutting paraffin-embedded sections on a rotary microtome
biconcave knife
This microtome knife is recommended for cutting paraffin-embedded sections on a rotary microtome
biconcave knife
A biconcave knife is recommended for cutting paraffin-embedded sections using what microtome?
rotary microtome
This microtome have both straight sides
plane-wedge knife
this knife is 100 mm in length
plane-wedge knife
this knife is 25 mm in length
plane-concave knife
this microtome knife is 120 in length
biconcave knife
this microtome knife is 120 in length
biconcave knife
this microtome knife is recommended for frozen sections or for cuttingg extremely hard and tough specimens embedded in paraffin blocks
plane-wedge knife
Plane-wedge knives are recommended for what?
for frozen sections or for cuttingg extremely hard and tough specimens
Plane-wedge knives are recommended for what?
for frozen sections or for cuttingg extremely hard and tough specimens
Plane-wedge knives are recommended for frozen sections or for cuttingg extremely hard and tough specimens embedded in what?
embedded in paraffin blocks
Plane-wedge knives are recommended for frozen section or for cutting extremely hard and tough specimens embedded in paraffin blocks using what microtome?
using a base-sledge microtome or sliding microtome
These knives are usually provided with backs
- plane wedge knives
- plane concave knives
What is the purpose of backs in plane wedge and plane concave knives?
to maintain the CORRECT BEVEL ANGLE throughout honing
Detachable handles may bbe attached to the knife during sharpening
true or false
true
There is a cutting facet (bevel) found on what part of all knives?
found on the tapered edges of all knives
This is found on the tapered edges of all knives
cutting facet (bevel)
The sides of the cutting facet are less acutely inclined towards each other than the side proper
true or false
more acutely inclined
false
The sides of the cutting facet are less acutely inclined towards each other than the side proper
true or false
more acutely inclined
false
The cutting facet found on the tapered edge of all knives form the actual cutting edge of all knives
true or false
TRUE
The angle formed between the cutting edges is known as the what?
“Bevel angle”
Normally, what is the angle of the “Bevel Angle”?
27 to 32 degrees
Such angle (Bevel angle) is maintained for each knife by means of a what?
means of a slide-on back
This is a spring-loaded semi-circular metal sheet slipped on to the nife with one or more plane surfaces (plane wedge or plane-concave)
Slide-on back
What is the purpose of a slide-on back?
to hold the cutting edge at a constant, correct angle during the process of honing and stropping
Each knife should have its own corresponnding back which may be interchanged with another, to keep the bevel angle
true or false
SHOULD NOT BE INTERCHANGED
FALSE
Each knife should have its own corresponnding back which may be interchanged with another, to keep the bevel angle
true or false
SHOULD NOT BE INTERCHANGED
FALSE
A good cutting edge should be made of what?
good quality steel
This should be made of good quality steel
good cutting edge
These kinds of cutting edges are likely to become dull easily
too soft cutting edges
Too hard edges are likely to produce what?
- likely to produce nicks or jagged edges
- irregularities on the knife edge
- tears or striation on the tissue sections during cutting
These produces tears or striations on the tissue secions during cutting
too hard edges
A good cutting edge must be able to cut good sections form a paraffin wax block of about how thick?
2-3 microns thick
A good cutting edge must be able to cut good sections with only few serrations noted on examination
true or false
WITHOUT SERRATIONS
FALSE
A good cutting edge must be able to cut good sections with only few serrations noted on examination
true or false
WITHOUT SERRATIONS
FALSE
Safety razor blades may be used for what?
- for partially calcified materials
- paraffin sections
- frozen sections
These may be used for partially calcified materials, paraffin and frozen sections
safety razor blades
They are readily replaced when dull, and produce similarly good tissue sections as those cut with microtome knives
safety razor blades
Safety razor blades are unsatisfactory for sections more than 10 u
true or false
less than 10 u
false
Safety razor blades are unsatisfactory for sections more than 10 u
true or false
less than 10 u
false
Theoretically, the perfect and optimum cutting angle is obtained when the SIDES of the wedge knife ARE INCLINED at an angle of what?
15 degrees
When the sides of the wedge knife are inclined at an angle of 15 degrees, this causes maximum distortion and minimizing the penetration of the tissues
true or false
maximum penetration of the tissues and minimizing distortion
What must be done to prevent uneven sections, or alternate thin and thick section?
the knife should be INCLINED WITH A 5-10 degree clearance angle
What is the measurement of the clearance angle?
5-10 degrees
To prevent uneven sections, or alternate thin and thick sections, the knife should be inclined with a 5-10 degree clearance angle from the cutting facet so that the cutting plane will NOT COMPRESS THE BLOCK dduring the process of trimming
True or false
should be inclined with a 5-10 degree clearance angle from the CUTTING PLANE so that the CUTTING FACET will not compress the block during the process of CUTTING
false
The cutting edge must be thicker than the section being cut
true or false
must be thinner than the sectionn being cut
false
A good cutting edge muust be sharp enough to cut good sections from a paraffin wax block of how thick?
4 u thick
A good cutting edge muust be sharp enough to cut good sections from a paraffin wax block at 4 u thick without causing what?
without causing serrations
A good cutting edge muust be sharp enough to cut good sections from a paraffin wax block at 4 u thick without causing what?
without causing serrations
This should be removed from the microtome when the instrument is left unattended or when clearing the instrument
the knife or blade
How can the knife or blade be removed from the microtome when the instrument is left unattended or when cleaning the instrument?
Best done by unclamping the blade using the blade ejector on the left side of the guard to start moving the blade laterally out of the clamp
When removing the knife or blade, this is best done by unclamping the what?
unclamping the blade
When removing the knife or blade, this is best done by unclamping the blade, the using the BLADE EJECTOR on the right side of the guard to start moving the blade laterally in the clamp
true or false
on the left side of the guard to start moving the blade laterally out of the clamp
false
When removing the knife or blade, this is best done by unclamping the blade, the using the BLADE EJECTOR on the right side of the guard to start moving the blade laterally in the clamp
true or false
on the left side of the guard to start moving the blade laterally out of the clamp
false
For what reason must badly nicked knives with blunted ends have to undergo sharpening?
- to ensure optimum sectioning of tissue blocks
- to prevent gross irregularities on the tissue sections
Jagged edges, if not corrected, produce what?
produce tears or striations in tissue sections
What are the 2 stages of sharpening the knife?
- honing
- stropping
This involves the removal of gross nicks on the knife edge
honing
this knd of honing is to remove blemishes
coarse honing
This kind of honing is to acuire an even edge
honing proper
the degree of sharpness is proportional to the fineness of the abrasive used in sharpening
true or false
true
the degree of sharpness is proportional to the fineness of what?
fineness of the abrasive
This is a natural sharpening stone or hard grinding surface
hone
the hard grinding surface is called a what?
carborundum
this serves to remove nicks and irregularities on the knife edges
hone
What are the types of hones?
- Belgium Yellow
- Arkansas
- Fine carborundum
This type of hone is for manual sharpening when cutting edge has been rendered blunt or nicked
Belgium yellow
this type of hone usually gives the best result
belgium yellow
This type of hone gives more polishing effect than the belgium yellow
arkansas
This type of hone is much coarser
Fine caborundum
This type of hone is used ONLY FOR BADLY NICKED KNIVES followed by either belgium yellow or arkansas
fine carborundum
The surface of the hone is wiped clean with what?
with a soft cloth moistened with xylene
Why is the surface of the hone wiped clean with a soft cloth moistened with xylene?
to remove the scattered small particles of stones and metal
After wiping he surface of the hone clean with a soft cloth moistened with xylene, what is done after?
cover the thin film of mineral and clove oil, xylene, liquid paraffin or soapy water
Mineral and clove oil, xylene, liquid paraffin or soapy water is used to cover the surface of the hone for what purpose?
for lubrication
These are used for lubrication when covering the surface of the hones
MC SoLiXy
- Mineral and clove oil
- Soapy water
- Liquid paraffin
- Xylene
the “heel” is the head portion
true or false
handle portion
false
the “heel” (handle end) is drawn obliquiely or diagonally towards the operator on the stone until the “toe” (head portion) is reached
true or false
true
In honing, the knife is then turned over, and the other surface is again drawn backward, EDGE FIRST, with a HEEL TO TOE direction
true or false
drawn forward
false
This may be used to prevent movement of the hone during honing
a damp cloth
light lubricating oil or soapy water is used for lubrication
true or false
TRUE
The knife complete with handle and backing sheath is laid on the hone with the cutting edge facing away from the operator and the heel roughly at the center of the nearest of hone
true or false
true
The knife is held with thumb on the back and forefinger on the front surface
true or false
true
in honing, the minot or plane-wedge knife, the knife is turned over as to sharpen the other surface every how many strokes?
10 - 20 strokes
for these knives, the knife is turned over as to sharpen the other surfaceevey 10-20 strokes
in minot or plane-wedge knives
for these knives, only the concave surface should be rubbed on the hone
for plane-concave knives
For plane-concave knives, what part should be rubbed on the hone?
only the concave surface
this may be used for grinding and removing nicks
aluminum oxide made into paste with water
How can a flat circular glass plate with finely powdered aluminum oxide made into paste with water be used for grinding and removing nicks?
used as an abrasive
This may be used for final polishing
Diamantine
how many inches thick is the plate glass
1/4 to 3/8 inch thick
how many inches long is the glass plate?
14 inches long
the glass plate is 1-2 inches wider than the length of the knife blade to be sharpened
true or false
true
the knife blade does not have to be held obliquely, but is pushed and pulled forard and backward at right angles to the transverse diameter of the plate due to what?
due to the plate’s relatively greater width
due to the plate’s relatively greater wdth, the knif blade does not have to be be held obliquely
true or false
true
due to the plate’s relatively greater width, the knife blade is pushed and pulled forward and backward at what angles?
right angles
Mechanical honing with machines may make use of what?
use of a vibrating frosted glass plate or a wheel driven by an electric motor
In mehcanical honing with machines, the knife is pressed against the what?
pressed against the flat side of a rotating glass wheel
in mechanical honing with machines, the knife is pressed against the flat side of a rotating glass wheel which is being driven by a what?
driven by a mechanical device
Approximately how many strokes are done in mechanical honing with machines?
approx 30 double strokes
aprrox 30 double trokes are given each side o the knife to which very gentle pressue is applied
true or false
true
the hone should be long enough, specifically what measurement?
about 8 x 3 inches
Badly nicked knives require greater and longer honing than less irregular knives
true or false
true
the hone should be cleaed before, during, annd after use
true or false
true
What develops in the hone usually imparted by the knife that is being sharpened?
a black film
The hone should be lubricated with warm soapy water or fine oil before using
true or false
true
This is the process whereby the “burr” formed during honing is removed and the cutting edge of the knife is polished
stropping
what is the purpose of stropping?
- to polish and shapen the cutting edge
this is to remove the irregualrities from the knife
honing
during what case is it only necessary to strop a knife?
when the knife has become blunt and dull but is free from nicks or teeth
for delicate work, the knife is stropped before every object is sectioned
true or false
true
this is made up of the best quality horse leather
paddle strop
the paddle strop is firmly attached to a what?
firmly attached to a solid back
this is used in order to prevent sagging
paddle strop
Stropping moves in what direction?
in a toe to heel direction
around how many strokes are usually required for stropping?
40-120 double strokes
in stropping, the knife is turn around at the end of each stroke so as to sharpen each surface alternately in the case of plane-concave knives
true or false
in the case of plane-wedge or minot knives
false
in honing, the knife is turned around every after 10-20 strokes so as to sharpen the other surface in the case of what?
in the case of plane-wedge or minot knives
for plane-concave knives, honing and stropping are the same wherein only the concave surface should be honed and stropped, respectively
true or false
true
The knife should always be wiped clean with a soft cloth before and after a series of stropping strokes and before changing from a coarse to a fine strop
true or false
true
after stropping is satisfactorily completed, what is then done?
knife edge is then oiled or greased
after stropping satisfactorily completed, why must the knife edge be oiled or greased?
to prevent the knife edge from rusting
the knife is kept in a what to prevent the settling of dust and grit on its surface, causing damage to the knife edge?
kept in a suspension box
In stropping, the knife should not be allowed to rest on its sides sine this may also damage the cutting edge
true or false
true
speed in stropping should be avoided
true or false
true
how many seconds should be allowed for each stroke to avoid injury to the strop and the knife?
one full second
in stropping, leather strops are usually dry and require oiling before they are used
true or false
true
strops are usually treated with vegetable oil (i.e., castor oil)applied into the back of the strop, NOT THE SURFACE
True or false
true
the strop should not be used for at least how many hours after treatment?
24-48 hours
this will make the stroppng surface slippery and will render the procedure unsatisfactory
too much oil
the surface is scraped with a blunt instrument (i.e., the bac of the knife) in order to what?
to remove the excessive oil
this is not recommended and should NEVER come in contact with a strop
mineral oil
why is mineral oil not recommended and should never come in contact with a strop?
it will tend to blister and destroy the leather
this will spoil the polish of the area and produce a permanent blemish on the strop
one drop of mineral oil
this is to prevent the turning of the knife’s edge (stropping)
stropping surface should be firm and not loose
strops are usually mounted on a WHAT and covered wita WHAT to prevent them frm sagging
mounted on a wooden canvass and covered with a flat pad
sharpening = honing; polishing = stropping
true or false
true
honing and stropping are no longer common practice in most modern laboratories because of what?
because of the availability of disposable knives
disposable knives are cheaper to use than conventional teel knives
true or false
true
they have a sharp cutting edge that can cut 2-4 u thick sections with ease
disposable blades
these knives are also now available that can attach to some blade holders and are particularly suitable for use in the cryostat
magnetic knives
these are generally used for trimming and semi-thin sectioning of tissue blocks for electron miroscopy
glass knives
they are prepared from commercially available 40 x 2.5 cm plate glass strips
glass knives
these are plate glass strips that have been washed with detergnt, rinsed in distilled water and alcohol, and dried with lint-free paper
glass knives
cleaned strips of a glass knife are clamped into a what?
clamped into a knife maker
cleaned strips of a glass knife are scored with a what?
scored with a tungsten carbide weel
cleaned strips of a glass knife are cracked to form square pieces of how many mm?
25 x 25 mm square pieces
these are used to cut any type of resin block for electron microscopy
diamond knives
when diamond knives are supplied by the manufacturer, they are already mounted in a metal block design to fit directly into the knife holder of what microtome?
ultrathin microtome
