Histopathology (a compound of three Greek words:
Video Histopathology
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Histopathological examination of tissue begins with surgery, biopsy, or autopsy. The tissue is removed from the body or plants, and then... often follows the expert's dissection in a fresh state... placed in a fixative that stabilizes the tissue to prevent decay. The most common fixation is formalin (10% neutral formaldehyde buffer in water).
Maps Histopathology
Preparation for histology
The tissues are then prepared for viewing under a microscope using chemical fixations or frozen parts.
If a large sample is given, e.g. from a surgical procedure then a pathologist looks at tissue samples and selects the most likely part to produce a useful and accurate diagnosis - this section is removed for examination in a process commonly known as grossing or cutting. Larger samples were cut to properly place their anatomical structures on tapes. Certain specimens (especially biopsies) can undergo pre-inclusion to ensure correct tissue orientation in cassettes & amp; then in block & amp; then on a diagnostic microscope slide. These are then placed into plastic cassettes for most of the rest of the process.
Chemical fixation
In addition to formaldehyde, other chemical fixatives have been used. However, with the emergence of immunohistochemistry (IHC) dyeing and diagnostic molecular pathology testing in this specimen sample, formalin has become a chemical fixative standard in human diagnostic histopathology. The fixation time for very small specimens is shorter, and the standard exists in human diagnostic histopathology.
Processing
Water is removed from the sample sequentially using an increase in alcohol concentration. Xylene is used in the last dehydration phase rather than alcohol - this is because the wax used in the next stage is soluble in xylene where not in alcohol allows the wax to penetrate (infiltrate) the specimen. This process is generally automatic and done overnight. The wax infiltrated specimen is then transferred to individual specimen containers (usually metals). Finally, liquid wax is introduced around the specimen in the container and cooled to solidification so that it attaches into the wax block. This process is required to provide a fairly sufficiently oriented sample that is strong enough to get a thin microtome section for slides.
Once the wax embedded block is complete, the part will be cut from it and usually placed float on the surface of the water that scatter the part out. This is usually done by hand and is a skilled job (histotechnologist) with lab personnel making choices about which part of the wax microtom specimen is placed on the slide. A number of slides will usually be prepared from various levels across the block. After this, a thin section mounted on the slide is stained and a protective cover lining is mounted on top of it. For common stains, automated processes are usually used; but rarely used stains are often done by hand.
Processing frozen
The second method of histology is called the processing of frozen parts. This is a highly technical scientific method undertaken by a trained histologist (a specialist Medical Laboratory scientist in Histopathology 5-6 years of degree training) In this method, the tissue is frozen and thinly sliced ​​using a microtome installed in the cooling device below the freezing point. called cryostat. A thin frozen section is installed on the sliding glass, repaired immediately & amp; briefly in a fixative fluid, and colored using the same staining technique as the traditional waxed part. The advantages of this method are fast processing times, fewer equipment requirements, and a lack of laboratory ventilation. The disadvantage is the poor quality of the final slide. It is used in an intraoperative pathology for the determination that may be helpful in choosing the next step in surgery during a surgical session (eg, to determine early clarity of tumor resection margins during surgery).
Customized histology slide coloring
This can be done for slides processed by chemical fixation or frozen slides. To see tissue under a microscope, the parts are stained with one or more pigments. The purpose of coloring is to reveal the cellular components; counterstain is used to provide contrast.
The most commonly used stain in histopathology is a combination of hematoxylin and eosin (often abbreviated H & amp; E). Hematoxylin is used to color the blue nuclei, while eosin coloring the cytoplasm and the pink extracellular connective tissue matrix pink . There are hundreds of other techniques that have been used for cells selectively. Other compounds used to dye tissue parts include safranin, Red Oil, red congo, silver salts and artificial coloring. Histochemistry refers to the science of using chemical reactions between laboratory chemicals and components within the network. The most common histochemical technique is the blue reaction of Prussia Perls, which is used to show iron deposits in diseases such as hemochromatosis.
Recently, antibodies have been used to contaminate certain proteins, lipids, and carbohydrates. Called immunohistochemistry, this technique has greatly enhanced the ability to specifically identify cell categories under a microscope. Other advanced techniques include in situ hybridization to identify specific DNA or RNA molecules. This method of staining these antibodies often requires the use of freezing histology. The above procedures are also performed in the laboratory under supervision and accuracy by a specialist scientist of a trained medical laboratory (Histoscientist) Digital cameras are increasingly being used to capture histopathologic images.
Interpretation
The histologic slides are examined under a microscope by a pathologist, a medical qualified specialist who has completed a recognized training program. This medical diagnosis is formulated as a pathology report that describes histologic findings and opinions of pathologists. In the case of cancer, this is the network diagnosis required for most treatment protocols. In the removal of cancer, the pathologist will show whether the operating margin is cleaned, or involved (residual cancer left behind). This is done using the method of processing bread or CCPDMA.
In myocardial infarction
After myocardial infarction (heart attack), no histopathology is seen first ~ 30 minutes. The only sign that maybe the first 4 hours is the fiber waviness on the border. Then, however, coagulation necrosis begins, with edema and bleeding. After 12 hours, can be seen karyopyknosis and hipereosinofilia miosit with necrosis ribbon contraction in the margin, and the beginning of neutrophil infiltration. At 1 - 3 days there is continued coagulation necrosis with loss of nuclei and striation and increased infiltration of neutrophils to the interstitium. Until the end of the first week after the infarction there was an early disintegration of dead muscle fibers, neutrophil necrosis and early removal of dead cell macrophages at the border, which increased the following days. After a week there is also the beginning of granulation tissue formation on the margin, which matures over the next month, and increases collagen buildup and decreases selectivity until the myocardial scar is fully matured at about 2 months after the infarction.
See also
- Anatomical Pathology
- Molecular pathology
- Frozen section procedure
- Medical technologist
- Laser capture microdissection
- List of pathologists
References
External links
- Virtual Histology Course - University of Zurich (German, English version in preparation)
- Uterine cervical histopathology - digital atlas (IARC Screening Group)
- PathologyPics.com: Interactive histology database for Anatomical Pathology Practitioners as well as Pathological Trainologists.
- Histopathology Virtual Slidebox - University of Iowa
Source of the article : Wikipedia
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