Paraffin embedding

For routine immunohistochemestry, surgical and other tissues are embedded in paraffin which is a mixture of hydrocarbons. Automated paraffin tissue processors are commercially available that customize the schedule to meet specific needs. However, tissues of 

While tissue is in xylene, gradual infiltration with paraffin is carried out. For tissues of a small size, 2 to 3 hr of paraffin infiltration is adequate. For large tissues (5-10 mm), overnight infiltration is required. The temperature during infiltration must not be higher than 4° above the melting point of paraffin (54-58°C). 

Vacuum embedding can be carried out to remove air bubbles from the tissue and rapidly replace the clearing agent with paraffin. This approach is especially desirable for air-containing tissues such as lung or hard tissues such as fibrous or scar tissues. The vacuum should not exceed 400-500 mm of mercury to avoid damage to the tissue. 

Paraffin blocks are trimmed with a scalpel, a razor blade, or a hot spatula and mounted on wooden or fiber blocks. While being sectioned, longitudinal block edges must be parallel to the knife edge to obtain a ribbon. Paraffin sections of any thickness show compression, which is usually relieved when they are floated on a glass slide and dried. 

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Gill et al.21 Archival FFPE spinal cord tissue both paraformaldehyde-fixed frozen rat spinal cord tissue and paraffin-embedded same tissue To establish an optimal protocol for detection of low-abundance protein (NeuN) in human spinal cord FFPE tissue sections, testing three AR solutions of pH 6, alkaline, and acidic buffer, with three heating conditions 95,100, and 105°C Heating FFPE tissue sections in an alkaline buffer yields most effective AR-IHC staining results. 

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EXTRACTION OF DNA/RNA FROM FORMALIN-FIXED, PARAFFIN-EMBEDDED TISSUE BASED ON THE ANTIGEN RETRIEVAL PRINCIPLE... 

A simple and effective AR technique of boiling archival paraffin-embedded tissue sections in water to enhance the signal of IHC was developed to circumvent the deleterious effects of formalin fixation, which had previously... 

Compound (Miles Laboratories, Elkhart, IN), snap-frozen, and cut into sections for comparison with paraffin-embedded cell sections (3) FFPE Cell Blocks Six cell pellets were fixed in 10% neutral buffered formalin immediately after harvest, at room temperature for 6,12,24h, 3,7, and 30 days, respectively. For further comparison with the cell model system, recently collected sample of human breast cancer tissues were processed by OCT-embedding and snap-freezing the corresponding routine FFPE block that was obtained from the Norris Cancer Hospital and Research Institute at the University of Southern California Keck School of Medicine (USC). This tissue block was processed routinely (formalin-fixed 24h and processed by automatic equipment). 

For the frozen cell/tissue samples, RNA extraction was carried out by using the TRIzol reagent kit. For the paraffin-embedded cell/tissue, RNA extraction was carried out by two methods heating and nonheating using enzyme digestion for comparison. RT-PCR was performed to compare the results. A... 

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