After tissue processing, the tissue cassettes are moved to an embedding station for the next crucial step in preparing microscope slides.
Embedding: Orienting and Solidifying the Tissue
The primary purpose of embedding is to provide support and a consistent matrix for the tissue, allowing it to be thinly sectioned for microscopic examination. Here's a breakdown of what occurs at the embedding station:
- Transfer to Embedding Station: The tissue cassettes containing the processed tissue are taken to the embedding center.
- Tissue Removal and Orientation: The tissue is carefully removed from its cassette. Crucially, the pathologist or histotechnologist correctly orients the tissue within a mold. Correct orientation is critical for visualizing specific anatomical structures during microscopic analysis.
- Mold Selection: A metal mold of appropriate size and shape is selected to hold the tissue.
- Wax Embedding: The mold is partially filled with molten paraffin wax from a heated reservoir.
- Tissue Placement: The oriented tissue is carefully placed into the mold.
- Final Wax Pour: More molten wax is poured over the tissue to completely fill the mold.
- Cooling and Solidification: The mold is then placed on a cold plate to allow the wax to cool and solidify, creating a solid tissue block.
- Block Removal: Once the wax has fully solidified, the block is removed from the metal mold.
The Result: A Tissue Block Ready for Sectioning
The result of embedding is a solid paraffin block containing the tissue sample, properly oriented and ready to be sectioned on a microtome. This block provides the necessary support and uniformity for creating very thin slices (sections) suitable for mounting on microscope slides and subsequent staining and analysis.
