In tissue freezing procedures, the OCT Compound is used to prevent artifacts and ensure the tissue is frozen as quickly and accurately as possible. This compound is available in various forms, including powder and gel. Here are some tips to make tissue freezing easier and less risky: read the instructions carefully, label each vial, and freeze samples in the freezer before use.
Artifacts caused by OCT
When it comes to preparing tissues for OCT, freezing them is an important step. This procedure helps minimize artifacts and ensures that the tissue remains as intact as possible. To freeze tissues, use isopentane-2-methyl butane or a similar solvent. The solvent should cover all areas of the tissue, including the tissue itself, and should be allowed to settle for at least 30 seconds.
After OCT compound tissue freezing, tissue samples should be trimmed into 0.5 x 0.5 cm or smaller samples. Larger samples may lead to artifacts. To minimize this problem, use a grate placed over the opening of the liquid nitrogen transfer container. Once the frozen tissue has hardened, it should be placed into a pre-labeled specimen bag. The specimen should never be warmed.
Alcohol can help prevent the formation of artifacts. A suitable alcohol solution contains one part formalin to nine parts alcohol. Alcohol prevents the formation of ice crystals in the tissue. However, excessive alcohol is not a good substitute for formalin, which makes tissues more brittle. Further, excessive alcohol can dry out the samples.
When preparing tissues for OCT compound tissue freezing, it is essential to check for any air bubbles and ensure that the top surface of the sample is level. Uneven surfaces will lead to the formation of artifacts, which can be a difficult problem to correct.
While there are several benefits to using this method, it is essential to understand how the technique works before implementing it. Many specimens require a perfect orientation within the block. However, the method used in most cases is more accurate than paraffin embedding, and the procedure is quicker.
Cryo-Gel
In this study, we evaluated the use of Cryo-Gel as an alternative embedding medium for OCT. The gel is highly viscous, completely water-soluble, and biodegradable. Cryogels are polymeric gels formed during freezing and are frequently used in biotechnology and tissue engineering applications. We first explored the feasibility of using Cryo-Gel to snap-freeze renal biopsies, followed by an analysis of the tissues embedded in it. We found that the Cryo-Gel samples had similar results to those of normal tissue samples.
If we compared the RIN values of samples embedded in Cryo-Gel and those that were not. We found that samples embedded in Cryo-Gel and OCT had similar RIN values, but they were higher in the Cryo-Gel samples than those without compound.
Also, we studied the effect of Cryo-Gel on IF. We split a renal biopsy sample into two parts, with one half embedded in OCT and the other half in Cryo-Gel. Then, we cut three-micrometer sections from both parts and performed immunofluorescence (IF) on both samples. For each of these sections, we performed IF for IgG, IgA, C3c, C3q, kappa, and lambda, following standard diagnostic methods. To evaluate the IF results, two pathologists assessed the intensity and quality of staining using the OCT embedded sample.
For OCT Compound Tissue Freezing, the procedure can be done using the Peel-A-Way freezing mold. To use OCT Compound Tissue Freezing, it is necessary to prep the tissue for snap-freezing by drying it using 2-methyl butane in a shallow Styrofoam box. Then, gently place the tissue into the Cryo-Gel-filled cryomold and freeze it. Once the section has reached -20 degrees Celsius, it must be placed on a positively-charged glass slide. Then, the section must be allowed to air dry before removing it from the freezer.
Cryo-Gel is a nonreactive, thermoplastic compound that is used to snap-freeze biopsy material. It contains polyethylene glycol or polyvinyl alcohol as well as other nonreactive ingredients. The compound helps stabilize the tissue and allows for easy positioning in the microtome. Furthermore, it preserves the morphologic characteristics of the tissue.
The Tissue-Tek OCT Compound is a clear, water-soluble mixture of resins and glycols that provides a solid matrix for frozen tissue specimens. It prevents background staining and ensures a fast freezing process. The compound is available in 4-oz squeeze bottles and comes in packs of 12 per case.
OCT Compound is a water-soluble blend of glycols and resins developed for cryostat sectioning. This compound is ideal for chromogenic IHC. It won’t dull microtome knives and leaves no residue on slides.
A comparison of OCT and Cryo-Gel samples reveals that the gel and OCT samples produce similar protein identification results. The only difference between the two is the time required to freeze the samples. MS on both samples reveals that the samples have similar protein identification. In addition, OCT samples exhibit polymer peaks that interfere with the MS signal.
Click here to read more: https://www.scigenus.com/product-page/o-c-t-compound
Without compound
Another technique for freezing tissue samples involves using liquid nitrogen to freeze the tissue specimen. Liquid nitrogen is a clear liquid, which makes it easier to use during the freezing process. It also avoids background staining, resulting in fast freezing. Liquid nitrogen is available in large and small containers and is convenient for use in freezing fresh tissue specimens.
The new method for freezing tissue samples eliminates the need for precision-fitting samples. It requires freezing and thawing cells only once, resulting in minimal damage to their cellular architecture, antigenic epitopes, and nucleic acid structures. It also preserves the natural biological activity of the cells and enhances the accuracy of the microarrays.
However, tissue samples that have been fixed with OCT are difficult to analyze by MS because of the polymers that interfere with ion formation. OCT can also conceal smaller peaks, making it more difficult to extract the proteins from the samples. Additionally, removing OCT from samples is a complicated procedure and will lower the protein yield.
Another method of tissue freezing involves using a substance called Agarose-OCT. This is a water-soluble mixture of polyethylene glycol and polyvinyl alcohol that has become widely used in tissue freezing. OCT has a variety of benefits, including the ability to support tissue, increase its continuity, and reduce the appearance of wrinkles, pleated tissue, and chipped tissue. It also helps prevent background staining. The OCT-frozen section method is compatible with a variety of storage methods. It can last up to 24 months.
Thanks for visiting mwposting