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Immunohistochemistry can be performed on tissue that has been fixed and embedded in paraffin, but also cryopreservated (frozen) tissue.Based on the way the tissue is preserved, there are different steps to prepare the tissue for immunohistochemistry, but the general method includes proper fixation, antigen retrieval incubation with primary antibody, then incubation with secondary antibody.
This process recovers the antigens masked by formalin fixation. As a result, it enables the successful application of immunohistochemistry on formalin fixed paraffin embedded tissue sections. Without antigen retrieval, most immunostains on formalin fixed paraffin embedded tissue sections show no staining.
In the tissue microarray technique, a hollow needle is used to remove tissue cores as small as 0.6 mm in diameter from regions of interest in paraffin-embedded tissues such as clinical biopsies or tumor samples. These tissue cores are then inserted in a recipient paraffin block in a precisely spaced, array pattern.
The substance used to embed tissue is embedding media, which is chosen depends on the category of the microscope, category of the micro tome, and category of tissue. [23] Paraffin wax, whose melting point is from 56 to 62°C, is commonly used for embedding. [22] Tissue processing - Tissue sections on slides are stained on an automated stainer
Formalin fixation leads to degradation of mRNA, miRNA, and DNA as well as denaturation and modification of proteins in tissues. However, extraction and analysis of nucleic acids and proteins from formalin-fixed, paraffin-embedded tissues is possible using appropriate protocols. [14] [15]
The microtome device that cold cuts thin blocks of frozen tissue is called a cryotome. [2] The quality of the slides produced by frozen section is of lower quality than formalin fixed paraffin embedded tissue processing. While diagnosis can be rendered in many cases, fixed tissue processing is preferred in many conditions for more accurate ...
The laser microtome has the ability to slice almost every tissue in its native state. Depending on the material being processed, slice thicknesses of 10 to 100 μm are feasible. Sectioning intervals can be classified mainly into either: Serial sectioning: obtaining a continuous ribbon of sections from a paraffin block and using all for slides.
Frozen section procedure: tissue embedded in optimal cutting temperature compound, mounted on a chuck in a cryostat and ready for section production. Optimal cutting temperature (OCT) compound is used to embed tissue samples prior to frozen sectioning on a microtome-cryostat. This process is undertaken so as to mount slices (sections) of a ...