Lesson 9: Cutting, Fishing, and Floatation

Question 1

The angle between the block face and lower facet of knife

5-10 degree angle

Answer 1

Clearance Angle

Question 2

27-32 degrees angle

Answer 2

Bevel Angle

Question 2

Angle of the edges of the wedge knife. This us the body of the knife blade

15 degrees

Answer 2

Wedge Angle

Question 3

Note:

The smaller the clearance angle, the sharper the knife but less sturdier

The larger the clearance angle, the lesser the sharpness of the knife is but more sturdier

Answer 3

Okay!

Question 3

Angle between the upper bevel of the knife and the perpendicular line drawn from the surface of the knife

Answer 3

Rake Angle

Question 4

Identify the Microtome Knife

120mm in length
Both sides concave, is recommended for cutting paraffin embedded sections on a rotary microtome.
NOT SUITABLE: hard materials, causes the edge to vibrate and produces “Chattering”

Answer 4

Biconcave Knife

Question 4

Identify the Microtome Knife

100mm in length
Both sides are straight and is recommended for frozen sections or for cutting extremely hard and tough specimens embedded in paraffin blocks, using a base-sledge or sliding microtome.

Answer 4

Plane-Wedge Knife

Question 5

Identify the Microtome Knife

25mm in length
One side of the knife is flat while the other is concave
Less concave side: for celloidin-embedded tissue blocks
More concave side: for paraffin sections on base-sledge

Answer 5

Plane-Concave

Question 6

Also called Ralph Knives

Answer 6

Glass Knives

Question 6

Knives that are manufactured from high quality stainless steel and edge can be coated with:

Platinum/Chromium = enhance the strength and prolong the cutting life.
Teflon = are particularly suitable for the use in cryostats.

Answer 6

Disposable Knives

Question 7

Note: Bubbles accumulating under the ribbon may then be removed with a smooth teasing needle, care being taken not to tear the section.

Answer 7

Noted!

Question 7

This knife is used for ultramicrotomy, the knife is positioned against or across the thickness of the glass

Answer 7

Glass Knives

Question 7

Identify the Knife

Manufactured from gem quality diamonds without flaws and extremely durable due to its hardness.

Used for cutting very thin sections

Answer 7

Diamond Knives

Question 7

It is the intermediate step between cutting paraffin sections and placing them on slides.

Answer 7

Water bath or flotation bath

Question 8

Why should the flotation be 30 seconds long only?

Answer 8

Because the paraffin could melt