TISSUE MICROTOMY
PREPARED BY MR. ABHIJIT DAS
Tissue microtomy is the technique of cutting extremely
thin sections of tissue samples for microscopic examination.
MICROTOME
A microtome is a specialized instrument used in laboratories to cut extremely thin sections of tissue for
microscopic examination. These sections, typically measured in microns (1
micron = 1/1000th of a millimeter).
Microtome Knife:
- A
microtome knife is a sharp blade used in
microtomes to cut thin sections of tissue
samples.
- It
must be extremely sharp and durable to produce consistent and precise cuts.
Disposable Knife:
- Disposable
knives are pre-sharpened, single-use blades, typically made of stainless
steel or other high-quality metals.
- They
are convenient, reduce maintenance, and eliminate the need for
resharpening.
Materials Used in Knives:
- Steel:
High-carbon steel or stainless steel is commonly used for microtome
knives.
- Glass: Used in specialized applications.
- Diamond:
Used for ultrathin sections.
Angles Of Knife:
· Bevel
Angle: Typically around 27 to 30 degrees.
· Clearance
Angle: Usually 3 to 8 degrees.
MICROTOME KNIFE SHARPENING
(MANUAL METHOD)
1. Honing:
- Place the knife on a honing stone.
- Move
the blade back and forth across the stone
at a consistent bevel angle (around 27-30 degrees) to remove nicks and
maintain sharpness.
- Ensure
even pressure and strokes on both sides of
the blade.
2. Stropping:
- After
honing, use a leather strop to further refine the edge.
- Gently
slide the knife across the strop to polish the edge and remove any burrs.
FACTORS INVOLVED IN CUTTING
TISSUE SECTIONS
1.
Knife Sharpness:
o A
sharp microtome knife is essential for producing clean, smooth sections.
2.
Angle:
o The
angle between the knife edge and the tissue block must be adjusted properly.
3.
Cutting Speed:
o The
speed at which the knife moves through the tissue block should be steady and
controlled.
4.
Tissue Hardness:
o Softer
tissues are easier to cut, while harder tissues require careful adjustment of
the microtome settings and knife angle.
5.
Temperature:
o Too
cold or too warm can impact section quality.