paraffinembedded

Paraffin embedding is a standard histological technique used to preserve and prepare tissue samples for light microscopy. After fixation, tissues are processed to remove water and solvents, then infiltrated with molten paraffin wax to form a solid block. The resulting paraffin-embedded tissue can be stored for long periods and cut into very thin sections for mounting on slides. In literature, paraffin-embedded tissue refers to samples that have undergone this process.

Typical workflow begins with fixation in formalin to preserve morphology, followed by graded dehydration with alcohols and clearing with a solvent such as xylene or a substitute. The tissue is then infiltrated with molten paraffin, embedded in a paraffin mold, and allowed to cool. Sections usually measure 3–5 micrometers and are mounted on positively charged slides for staining.

Paraffin-embedded tissue supports routine histology, special stains, and immunohistochemistry after deparaffinization and antigen retrieval. The method enables long-term archival storage of blocks and slides, facilitates batch processing, and provides high-quality tissue architecture for diagnostic and research purposes.

Advantages include stable preservation of morphology and compatibility with a wide range of stains. Limitations include potential antigen masking requiring retrieval steps, the risk of processing artifacts, and the need for hazardous chemicals such as formalin and organic solvents. Paraffin embedding is slower than frozen section methods and is not suitable for analyses requiring unfixed or fresh tissue, but it remains widely used due to durability, standardization, and compatibility with many downstream assays.