Содержание
- 2. Contents Introduction Specimen Accessioning Gross Examination Tissue Processing steps The paraffin Technique and its alternatives The
- 3. Introduction There are 3 main techniques which are used in preparing microscopical sections from tissues: The
- 4. …Introduction Tissues from the body taken for diagnosis of disease processes must be processed in the
- 5. Specimen Accessioning Tissue specimens received in the surgical pathology laboratory have a request form that lists
- 8. Gross examination Tissues removed from the body for diagnosis arrive in the Pathology Department and are
- 10. …Gross examination Note: When a malignancy is suspected, then the specimen is often covered with ink
- 12. Tissue Processing steps Biological tissues are generally rather soft, making it quite difficult to cut acceptably
- 13. …Tissue Processing steps The usual way this is done is with paraffin. Tissues embedded in paraffin,
- 14. The paraffin Technique Washing Following fixation, the tissues should be washed from 15 to 30 minutes.
- 15. ...The paraffin Technique Dehydration Wet fixed tissues (in aqueous solutions) cannot be directly infiltrated with paraffin.
- 16. …The paraffin technique Clearing The next step is called "clearing" and consists of removal of the
- 17. …The paraffin technique Impregnation in paraffin The tissues are put from 6 – 24 hours in
- 18. …The paraffin technique Embedding Finally, the tissue is infiltrated with the embedding agent, almost always paraffin.
- 19. …The paraffin technique Infiltration must be carried out at only a few degrees above the melting
- 20. …The paraffin technique Paraffin can be purchased that differ in melting point, for various hardnesses, depending
- 21. …The paraffin technique Using a completely different rationale for dehydration, Prento (1978) was able to reduce
- 22. …The paraffin technique Upon solidifying, paraffin shrinks 16.5 percent in volume. Paraplast is supposed to shrink
- 23. …The paraffin technique The above processes are almost always automated for the large volumes of routine
- 24. …The paraffin technique Tissues that come off the tissue processor are still in the cassettes and
- 26. Alternatives to paraffin embedding Alternatives to paraffin embedding include various plastics that allow thinner sections. Such
- 27. Note: Plastics require special reagents for dehydration and clearing that are expensive. For this reason, and
- 28. The freezing Technique In this method, the fresh or fixed tissues are frozen hardened and cut
- 29. Problems in Tissue Processing "Floaters" are small pieces of tissue that appear on a slide that
- 30. Problems in Tissue Processing If reusable cassettes are employed, you must be aware that tissue may
- 31. Problems in Tissue Processing Always be sure that you properly identify the tissue! This means that
- 32. Problems in Tissue Processing You must never submit a cassette of tissue with the wrong label.
- 33. Sectioning Frozen Sections Staining H & E staining Coverslipping Decalcification Artefacts in Histologic Sections
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