Lec 4: Sectioning & Embedding

Question 1

Placing the tissue in the paraffin wax in a precisely arranged position

Answer 1

Embedding

Question 2

Refers to the material used to infiltrate, support, and enclose specimens that will cut into thin sections.

Answer 2

Embedding media

Question 3

Purpose of ice

Answer 3

• prevent paraffin crystal formation
• accelerate hardening

Question 4

Types of Embedding Molds

Answer 4

• Pop-out hinge embedding mold
• Leuckhart’s embedding mold
• Compound embedding unit
• Plastic embedding rings & base mold
• Disposable embedding mold

Question 5

The type of embedding mold we use in the laboratory.

Answer 5

Pop-out hinge embedding mold

Question 6

• consists of two L-shaped strips of heavy brass/metal arranged on a flat metal plate

Answer 6

Leuckhart’s embedding mold

Question 7

Advantages of Leuckhart’s Embedding Mold

Answer 7

• can adjust its size to the size of the specimen
• produces even blocks with parallel sides

Question 8

Advantages of Leuckhart’s Embedding Mold

Answer 8

• can adjust its size to the size of the specimen
• produces even blocks with parallel sides

Question 9

• made up of series of interlocking plates resting on a flat metal base, forming several compartments

Answer 9

Compound Embedding Unit

Question 10

Compound Embedding Unit
1. Advantage
2. Disadvantage

Answer 10

1. Embedding more specimens at a time
2. Labels can be removed

Question 11

• an automated embedding unit
• consists of a special stainless steel base mold fitted with a plastic embedding ring

Answer 11

Plastic embedding ring and base mold

Question 12

Advantage of Plastic embedding ring and Base mold

Answer 12

The plastic embedding ring serves as a block holder during cutting

Question 13

• peel away
• paper boat
• plastic ice trays

Answer 13

Disposable Embedding Mold

Question 14

Temperature of Calibration for the Electric Paraffin Wax Dispenser

Answer 14

• 58 to 60°C

OR

• 2 to 5°C above the melting point of paraffin

Question 15

Purpose of Paraffin Bath

Answer 15

To place the impregnated tissues before embedding

Question 16

• removing excess wax at the sides, top, and bottom of the block
• exposes tissue surface

Answer 16

Trimming

Question 17

TRIMMING
1. All sides are ___ to form a ____ prism or ____.
2. Thickness of sections.
3. A series of tissue sections.

Answer 17

1. All sides are parallel to form a four-sided prism or truncated pyramid.
2. 4 to 6 microns
3. Ribbon

Question 18

What are the requirements for a successful sectioning of paraffin blocks? (3)

Answer 18

• Microtome
• Sharp (disposable) knife
• Microtomist’s / Technologist’s skills

Question 19

• by Paldwell Trefall (1881)
• for cutting serial sections of large blocks
• phased out

Answer 19

Rocking Microtome

Question 20

• by Minot (1885-1886)
• for paraffin-embedded sections

Answer 20

Rotary Microtome

Question 21

• by Adams (1789)
• for celloidin-embedded sections

Answer 21

Sliding Microtome

Question 22

2 types of Sliding Microtome

Answer 22

1. Base Sledge Microtome
   
   • block holder moves under the knife
2. Standard sliding Microtome
   
   • block is stationary, while knife moves

Question 23

• by Queckett (1848)
• a Rotary Microtome inside a refrigerated chamber

Answer 23

Freezing Microtome

Question 24

• for STAT diagnosis
• for cutting unembedded frozen sections

Answer 24

Freezing Microtome

Question 25

- latest freezing Microtome - for cutting frozen samples

Answer 25

Cryostat Microtome

Question 26

- for cutting sections for Electron Microscopy - 0.5 to 1 micro thickness

Answer 26

Ultrathin Microtome

Question 27

- automated - vibrates

Answer 27

Vibratome

Question 28

**MICROTOME PARTS** 1. For cutting of tissue section 2. Found on the _right side_ of Microtome, and operates in a _clockwise rotation_ 3. Found on the left side of Microtome, and adjusts the block holder forward/backward from the knife. 4. Holds the block tightly during cutting

Answer 28

1. Knife holder & knife 2. Flywheel or Handwheel 3. Pawl Ratchet Feed Wheel 4. Block Holder

Question 29

The angle formed between the cutting edge of the knife - held constant - a.k.a. Facet

Answer 29

Bevel Angle

Question 30

The angle between the tissue block and the cutting edge of knife

Answer 30

Clearance Angle

Question 31

1. What is the Clearance Angle? 2. Give the Bevel Angle.

Answer 31

1. 0 to 15° 2. Usually 27 to 32°

Question 32

- one side of the knife is flat while the other is concave

Answer 32

Plane-Concave knife

Question 33

1. The less concave knife is used for cutting ___ embedded tissue sections. 2. The more concave knife is used to cut ___ embedded tissue sections.

Answer 33

1. Celloidin 2. Paraffin

Question 34

Used for cutting paraffin sections but a rarely used

Answer 34

Biconcave knife

Question 35

- Most commonly used - disposable - both sides are straight

Answer 35

Plane wedge knife

Question 36

Type of knife used for frozen sections or extremely hard specimen blocks.

Answer 36

Plane wedge knife

Question 37

Used for trimming and semi thin sectioning of tissue blocks for electron microscopy

Answer 37

Glass knife

Question 38

- Used to cut any type of resin block for electron microscopy - brittle and expensive but very durable

Answer 38

Diamond knife / Broken Plate Glass