Tissue processing

Each step in the process must be carefully executed to maintain the integrity of the tissue and obtain reliable results.

• Fixation: The first step in tissue processing involves fixing the tissue samples. Fixation helps preserve cellular structures and prevent decay. Formalin is a commonly used fixative solution that penetrates tissues and forms cross-links between proteins, stabilizing them.

• Dehydration: After fixation, the tissue samples are dehydrated to remove water and replace it with a substance that can be embedded easily. This is typically done by passing the tissue through a series of alcohol solutions of increasing concentration.

• Clearing: Following dehydration, the tissue samples undergo clearing to remove the alcohol and make them transparent. Clearing agents, such as xylene or other organic solvents, are used for this purpose.

• Embedding: Once cleared, the tissue samples are embedded in a supporting medium, such as paraffin wax. Embedding provides structural support to the tissue and facilitates sectioning. The tissue is placed in a mold filled with molten paraffin wax, which solidifies as it cools, encasing the tissue.

• Sectioning: After embedding, the tissue blocks are trimmed and sectioned into thin slices using a microtome. These sections are typically between 3 to 5 micrometers thick and are mounted onto glass slides for staining and examination.

• Staining: Tissue sections are stained to enhance contrast and visualize specific cellular components or structures. Common stains used in pathology include hematoxylin and eosin (H&E), which stains nuclei blue and cytoplasm pink, respectively. Special stains may also be used to highlight specific features or pathological changes.

• Cover-slipping: After staining, the tissue sections are cover-slipped by placing a coverslip over the stained section using mounting medium. Cover-slipping protects the tissue sections and provides a clear optical path for microscopic examination.

• Microscopic Examination: The final step involves examining the stained tissue sections under a microscope. Pathologists and laboratory technicians analyze the tissue morphology, identify abnormalities, and make diagnostic interpretations based on the observed features.

Tissue processing is a critical aspect of pathology that ensures the preservation, visualization, and accurate interpretation of tissue samples for diagnostic and research purposes.

View other equipment details:

Grossing station || Cryotome