Tissues are prepared for thin sectioning primarily through a process involving precision sawing, embedding in resin under vacuum, and subsequent grinding and polishing. This meticulous procedure ensures the creation of extremely thin, uniform sections suitable for microscopic examination.
Here's a breakdown of the steps involved:
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Sectioning with a Precision Saw:
- The initial step often involves using a precision saw to cut the tissue specimen into smaller, more manageable pieces. This helps to obtain a smoother surface for subsequent processing.
- The choice of saw and blade depends on the hardness and fragility of the tissue.
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Embedding in Resin:
- The tissue sample is then embedded in a castable resin, typically an epoxy or acrylic resin. This provides support and stability during the thin sectioning process.
- Embedding is often performed under vacuum to remove air bubbles that can interfere with sectioning quality. Vacuum embedding ensures complete resin infiltration and a homogenous block.
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Grinding and Polishing:
- Once the resin has hardened, the embedded tissue block is meticulously ground and polished to achieve the desired thinness (typically a few micrometers or even nanometers).
- This is achieved using a series of progressively finer abrasive materials and polishing cloths.
- Grinding and polishing are critical for removing surface imperfections and producing a flat, even surface that's conducive to high-resolution microscopy.
Alternative Method:
In some cases, particularly with delicate tissues, embedding may precede initial sectioning with a saw. This provides added support during the initial cutting stage and can minimize damage.
Summary Table:
| Step | Description | Purpose |
|---|---|---|
| Precision Sawing | Cutting the tissue specimen with a precision saw. | To create smaller, manageable pieces and provide a smoother surface. |
| Resin Embedding | Embedding the specimen in a castable resin under vacuum. | To provide support and stability during thin sectioning and to ensure complete resin infiltration. |
| Grinding and Polishing | Using progressively finer abrasive materials to grind and polish the resin block containing the tissue. | To achieve the desired thinness and remove surface imperfections. |
This process enables the creation of thin sections which can be examined using various microscopy techniques such as light microscopy, transmission electron microscopy (TEM), and scanning electron microscopy (SEM), facilitating detailed analysis of tissue structure and composition.
