The tissue sample preparation process typically involves the following steps:
1.
Fixation: This step involves preserving the tissue to prevent decay and autolysis. Common fixatives include
formaldehyde and
glutaraldehyde. Fixation stabilizes the cell structure and proteins, making the tissue suitable for further processing.
2. Dehydration: The tissue is gradually dehydrated through a series of alcohol solutions, often starting with a lower concentration and moving to higher concentrations. This step removes water from the tissues, which is essential for the embedding process.
3.
Clearing: In this step, the tissue is treated with a clearing agent such as
xylene or
toluene. Clearing agents make the tissue transparent and prepare it for infiltration with the embedding medium.
4.
Embedding: The cleared tissue is then embedded in a medium, usually
paraffin wax or a resin. This provides support to the tissue, enabling thin sectioning.
5. Sectioning: Using a microtome, the embedded tissue is sliced into thin sections, usually between 3-5 micrometers thick. These sections are then placed on microscope slides for staining.
6.
Staining: Staining is crucial for adding contrast to the tissue sections, making different structures distinguishable. Common stains include
Hematoxylin and Eosin (H&E), which highlight general tissue architecture, and specific stains like
Periodic Acid-Schiff (PAS) for carbohydrates.
