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Tissue embedding in paraffin is important in preserving tissue in morphology and giving the tissue support during sectioning. This protocol also describes how to cut sections from tissue sections in paraffin blocks. Let see the steps involved in paraffin embedding: fixation, dehydration, transparentizing, immersion and embedding.
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Paraffin Embedding Paraffin embedding is a method of tissue preservation for immunohistochemistry. When we generating paraffin embedded tissue sample, the tissue should be fixed before embedding in paraffin. Immunostaining provides the basic guide for fixation, microtome sectioning and staining of paraffin – embedded tissue sections.
1. Fixation This is the process by which the constituents of cells and tissue are fixed in a physical and chemical state so that they will with stand subsequent treatment with various reagents with minimum loss of architecture. This is achieved by exposing the tissue of chemical compound, call fixatives. 2. Dehydration Dehydration removes water completely, creates a condition for the next step and hardens the tissue of interest.
3. Transparentizing • After dehydration, the tissue of interest requires a transparentizing step because the dehydrating agent used in the previous step is immiscible with the paraffin from one of the subsequent steps. The addition of transparent reagent helps paraffin absorb into the tissue. 4. Immersion After transparentizing, the tissue can be immersed in molten paraffin wax so that it adsorbs the wax-substituting transparent agent. Based upon the melting point of wax, immersion should be performed at 54-64℃.
5. Embedding • This is a process of treating the tissue in a paraffin box so that the paraffin wax cools down and solidifies. The treatment conditions (using ethanol and xylene as an example) are shown in the table below. After cooling is completed, the tissue will be ready for sectioning and suitable for storage.
To know more about paraffin embedding, visit at http://immunostaining.info/ihc-principle/paraffin-embedding/