Trimming Flashcards
The process by which processed tissue is trimmed and cut into uniformly thin slices
MICROTOMY
Three parts of Microtome
Block holder (chuck)
Knife carrier and knife
Pawl,ratchet feed wheel and adjustment screws
For cutting serial sections of large blocks of paraffin embedded tissues
ROCKING MICROTOME
Invented by Minot in 1885-86
Used to cut paraffin embedded tissues
ROTARY MICROTOME
The knife and the block holder are brought together by upward and vertical motions
It is heavier and more stable than the rocking microtome
ROTARY MICROTOME
Invented by Adams in 1789
SLIDING MICROTOME
For cutting of celloidin-embedded tissues
Base sledge microtome
SLIDING MICROTOME
Invented by Queckett in 1848
FREEZING MICROTOME
A refrigerated apparatus used in fresh tissue microtomy
Cryostat
Used for cutting unembedded or gelatin-embedded blocks frozen in liquefied carbon dioxide, liquefied nitrogen,Freon and other refrigerants
FREEZING MICROTOME
Used for cutting tissue sections of 0.5 micra for electron microscopy
ULTRATHIN MICROTOME
Knives For electron microscopy
Glass knives
Knives For electron microscopy
Diamond knives
One side of the knife is flat while the other is concave
Plane-concave knife (25mm.in length)
Both sides are concave
Biconcave knife (120 mm. in length)
Both sides are straight
Plane-wedge knife (100mm in length)
The angle formed between the cutting edges
27°-32°
Bevel angle
The angle between the block face and lower facet of knife
10°-15°
Clearance angle
Removal of gross nicks on the knife edge (coarse honing)
To remove blemishes
HONING
Types of Honing
Belgian Yellow
Arkansas
Finecarborundum
Gives the best result
Belgian Yellow
10-20 strokes hone
plane-wedge knife
20-40 strokes hone
biconcave knife
Facilitates honing & removes metal cutting
Light oil
Dilute paraffin solution
Xylene
Lubricant
Process whereby the “burr” formed during honing is removed and the cutting edge of the knife is polished
Stropping
80-120 strokes on each side strope
Biconcave knife
