Podcast
Questions and Answers
What is the primary focus during the embedding process for tubular structures?
What is the primary focus during the embedding process for tubular structures?
What is the recommended orientation for stratified structures during embedding?
What is the recommended orientation for stratified structures during embedding?
When preparing muscle or nerve tissue for embedding, what is the suggested placement?
When preparing muscle or nerve tissue for embedding, what is the suggested placement?
How should multiple pieces of skin be arranged in a cassette for optimal embedding?
How should multiple pieces of skin be arranged in a cassette for optimal embedding?
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What is the effect of cutting tissues at an angle during embedding?
What is the effect of cutting tissues at an angle during embedding?
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What is the recommended way to position specimens for embedding?
What is the recommended way to position specimens for embedding?
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What should be checked before embedding specimens?
What should be checked before embedding specimens?
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What is crucial about the cooling process during the embedding of tissue?
What is crucial about the cooling process during the embedding of tissue?
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Which method is recommended for obtaining good quality sections of bone without decalcification?
Which method is recommended for obtaining good quality sections of bone without decalcification?
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Why is it not advisable to freeze specimens at temperatures much lower than -20°C?
Why is it not advisable to freeze specimens at temperatures much lower than -20°C?
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In a cryostat, what is the typical cutting temperature for soft tissue?
In a cryostat, what is the typical cutting temperature for soft tissue?
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What should be done to avoid tissue carryover between specimens?
What should be done to avoid tissue carryover between specimens?
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What effect does slow freezing have on tissue sections?
What effect does slow freezing have on tissue sections?
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Study Notes
Histology Review: The Process
- The process involves several steps, from tissue collection to generating a report.
- Tissue specimens are collected from various locations (clinics, doctor's offices, etc.).
- The specimen is then sent to a pathology lab.
- Accessioning, grossing, processing, embedding, microtomy, staining, and assigning are procedures in the pathology lab.
- The pathologist examines the stained specimen to generate a report.
Embedding & Specimen Orientation
- Specimen orientation is critical for effective analysis.
- Larger flat specimens are easiest to orient.
- Special instructions exist for different tissue types:
- Tubular structures (e.g., fallopian tube) are embedded on end, viewed from the side, and their lumen (opening) is shown.
- Stratified structures (e.g., skin) are embedded on edge.
- Cross-section and longitudinal views are required for tissues like muscle or nerves.
Special Instructions (continued)
- Multiple tissue pieces are embedded in straight lines within the mold.
- The angle of the tissue within the mold is important; ideally, the blade strikes the small point first, then the whole side of the tissue.
Striated Tissue
- The images, show a detailed layout of the stomach, with markings and labels for specific tissues and areas.
Multiple Pieces
- Arrange multiple pieces in a straight line within the mold.
- Maintain an orderly arrangement.
Tissue Angle
- The correct angle of the tissue within the embedding mold is critical.
- The blade should strike the tissue at a specific point.
- Avoid incorrect positioning, which leads to poor cuts.
Embedding
- Tissues cut better at an angle.
- Embed specimen in a 2-4 mm layer of wax.
- Avoid using too large a mold; it can make cutting difficult.
- Correct Tissue Embedding Procedure
- Skin slices are placed on edge, so that epidermis, dermis, and subcutaneous layers are all visible.
- Align pieces so all have the epidermis facing in the same direction.
Quality Control
- Embedding Quality Control Procedures:
- Ensure all specimens are on the same plane to easily locate.
- Carefully dispose of the discarded specimens.
- Follow Standard Operating Procedures (SOPs)
- Check for any processing issues.
- Check temperatures, wax quality, and the condition of the cooling plate.
- Tiny specimens are handled in specific ways:
- Arrange tiny and large specimens alternately.
- Position specimens centrally on a single plane.
- Maintain clean forceps during this process.
Check Instructions
- Review instructions before embedding a specimen.
- Only open one cassette at time to avoid cross-contamination/transfer.
Troubleshooting Embedding
- Verify correct specimen orientation prior to embedding.
- Check the embedded specimens before cutting to avoid orientation problems.
Tissue Carryover
- Maintain thorough cleaning practices between specimens.
- Only open one cassette at a time to prevent cross-contamination.
- Alternate tiny and large specimens when necessary.
Embed on One Level
- Firmly and evenly compact the tissue within the embedding mold.
- Avoid allowing the wax to cool prematurely.
- Maintain efficiency.
Tissue Pieces
- Document the number of tissue pieces.
- Refer to the embedding log or cassette for counts.
- Carefully open the cassette and check the top before discarding the material.
- Carefully open lens paper/maintain warmth during scraping.
Cassette Not Level in Mold
- Use forceps or spatulas to level cassettes; ensure proper seating within the embedding mold.
Frozen Sections
- Frozen sections are typically cut at -20 °C.
- The pathologist dissects the specimens.
- The sample is placed on a chuck with OCT compound.
- Then freeze, cut & report within 15-20 minutes.
Cryostat
- Best results from unfixed sections.
- Avoid slow freezing, which causes artifacts.
- Cryostat freezing methods:
- Liquid Nitrogen (-190°C)
- Isopentane (-150°C)
- Aerosol sprays (-50 °C)
- Lower freezing temperatures require longer extra time before slicing.
Temperature for Cutting
- 20°C typical temperature for cutting.
- Slightly warmer for water-based samples.
- Adjust temperature depending on material (avoid shattering or chattering).
- Lower temps for fat samples (to avoid rolling up).
Bone
- Cancellous (spongy) bone sections do not require decalcification.
- Useful for diagnosing bone tumors.
Rate of Cutting
- Soft tissues require slower cutting speeds.
- Hard tissues can be cut quickly.
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Description
This quiz covers the essential processes involved in histology from tissue collection to generating pathology reports. It highlights the importance of specimen orientation and includes special instructions for different tissue types. Test your knowledge on the critical steps in the laboratory workflow.
