Lec 4: Sectioning & Embedding Flashcards
Placing the tissue in the paraffin wax in a precisely arranged position
Embedding
Refers to the material used to infiltrate, support, and enclose specimens that will cut into thin sections.
Embedding media
Purpose of ice
- prevent paraffin crystal formation
- accelerate hardening
Types of Embedding Molds
- Pop-out hinge embedding mold
- Leuckhart’s embedding mold
- Compound embedding unit
- Plastic embedding rings & base mold
- Disposable embedding mold
The type of embedding mold we use in the laboratory.
Pop-out hinge embedding mold
- consists of two L-shaped strips of heavy brass/metal arranged on a flat metal plate
Leuckhart’s embedding mold
Advantages of Leuckhart’s Embedding Mold
- can adjust its size to the size of the specimen
- produces even blocks with parallel sides
Advantages of Leuckhart’s Embedding Mold
- can adjust its size to the size of the specimen
- produces even blocks with parallel sides
- made up of series of interlocking plates resting on a flat metal base, forming several compartments
Compound Embedding Unit
Compound Embedding Unit
1. Advantage
2. Disadvantage
- Embedding more specimens at a time
- Labels can be removed
- an automated embedding unit
- consists of a special stainless steel base mold fitted with a plastic embedding ring
Plastic embedding ring and base mold
Advantage of Plastic embedding ring and Base mold
The plastic embedding ring serves as a block holder during cutting
- peel away
- paper boat
- plastic ice trays
Disposable Embedding Mold
Temperature of Calibration for the Electric Paraffin Wax Dispenser
- 58 to 60°C
OR
- 2 to 5°C above the melting point of paraffin
Purpose of Paraffin Bath
To place the impregnated tissues before embedding
- removing excess wax at the sides, top, and bottom of the block
- exposes tissue surface
Trimming
TRIMMING
1. All sides are ___ to form a ____ prism or ____.
2. Thickness of sections.
3. A series of tissue sections.
- All sides are parallel to form a four-sided prism or truncated pyramid.
- 4 to 6 microns
- Ribbon
What are the requirements for a successful sectioning of paraffin blocks? (3)
- Microtome
- Sharp (disposable) knife
- Microtomist’s / Technologist’s skills
- by Paldwell Trefall (1881)
- for cutting serial sections of large blocks
- phased out
Rocking Microtome
- by Minot (1885-1886)
- for paraffin-embedded sections
Rotary Microtome
- by Adams (1789)
- for celloidin-embedded sections
Sliding Microtome
2 types of Sliding Microtome
- Base Sledge Microtome
- block holder moves under the knife
- Standard sliding Microtome
- block is stationary, while knife moves
- by Queckett (1848)
- a Rotary Microtome inside a refrigerated chamber
Freezing Microtome
- for STAT diagnosis
- for cutting unembedded frozen sections
Freezing Microtome
