Histopathology (from the Greek histos (tissue) and pathos (suffering)) refers to the microscopic examination of tissue in order to study the manifestations of disease. The optical microscope, often referred to as the "light microscope" is a type of Microscope which uses Visible light and a system of lenses to Specifically, in clinical medicine, histopathology refers to the examination of a biopsy or surgical specimen by a pathologist, after the specimen has been processed and histological sections have been placed onto glass slides. A biopsy (in Greek: βίος life and όψη look/appearance is a Medical test involving the removal of cells or tissues Pathology (from Greek grc πάθος pathos, "fate harm" and grc -λογία -logia) is the study and Histological section refers to thin slices of tissue applied to a Microscopic slide, usually around 5 to 10 Micrometres thick which are viewed This is the most important tool of the anatomical pathologist in routine clinical diagnosis of cancer and other diseases. Pathology; please do not remove --> ( Diagnosis is the identification by Process of elimination, of the nature of anything Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled A disease is an abnormal condition of an organism that impairs bodily functions and can be deadly
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Collection of tissues
Histopathological examination of tissues starts with surgery, biopsy or autopsy. Surgery (from the χειρουργική cheirourgikē, via chirurgiae meaning "hand work" is a medical specialty that uses operative manual and instrumental A biopsy (in Greek: βίος life and όψη look/appearance is a Medical test involving the removal of cells or tissues An autopsy, also known as a post-mortem examination, necropsy, or obduction, is a Medical procedure that consists of a thorough Examination The tissue is removed, and then placed in a fixative which stabilizes the tissues to prevent decay. In the fields of Histology, Pathology, and Cell biology, fixation is a chemical process by which Biological tissues are preserved from decay The most common fixative is formalin (10% formaldehyde in water). Formaldehyde is a Chemical compound with the formula H2CO It is the simplest Aldehyde —an organic compound containing a terminal Carbonyl Formaldehyde is a Chemical compound with the formula H2CO It is the simplest Aldehyde —an organic compound containing a terminal Carbonyl
Preparation for histology
The tissue is then prepared using histology procedures for viewing under a microscope. Histology (from the Greek = 'tissue' is the study of the microscopic anatomy of cells and tissues of Plants and A microscope ( Greek: ( micron) = small + ( skopein) = to look or see is an instrument for viewing objects that are Briefly, the samples are transferred to a cassette, a container designed to allow reagents to freely act on the tissue inside. This cassette is immersed in multiple baths of progressively more concentrated ethanol, to dehydrate the tissue, followed by toluene or xylene, and finally hot liquid paraffin. Toluene, also known as methylbenzene or phenylmethane, is a clear water -insoluble liquid with the typical smell of Paint thinners redolent of In chemistry paraffin is the common name for the Alkane Hydrocarbons with the general formula C n H2 n +2 During this 12 to 16 hour process, paraffin will replace the water in the tissue, turning soft, moist tissues into a sample miscible with paraffin, a type of wax. This process is known as tissue processing.
The processed tissue is then taken out of the cassette and set in a mold. Through this process of embedding, additional paraffin is added to create a paraffin block which is attached to the outside of the cassette.
The process of embedding then allows the sectioning of tissues into very thin (2 - 7 micrometer) sections using a microtome. Involuntary commitment is the practice of using legal means or forms as part of a Mental health law to commit a person to a Mental hospital, Insane asylum A microtome is a mechanical instrument used to cut biological specimens into transparent thin sections for microscopic examination The microtome slices the tissue ready for microscopic examination. The slices are thinner than the average cell, and are layered on a glass slide for staining.
To see the tissue under a microscope, the sections are stained with one or more pigments. The aim of staining is to reveal cellular components; counterstains are used to provide contrast.
The most commonly used stain in histopathology is a combination of hematoxylin and eosin. Haematoxylin, hematoxylin, Natural Black 1, or CI 75290 is extracted from the wood of the Logwood tree Eosin is a Fluorescent red Dye resulting from the action of Bromine on Fluorescein. Hematoxylin is used to stain nuclei blue, while eosin stains cytoplasm and the extracellular connective tissue matrix pink. In Cell biology, the nucleus (pl nuclei; from Latin la ''nucleus'' or la ''nuculeus'' "little nut" or kernel is a membrane-enclosed The cytoplasm is the contents of a cell that is enclosed within the Plasma membrane. There are hundreds of various other techniques which have been used to selectively stain cells. Other compounds used to color tissue sections include safranin, Oil Red O, congo red, silver salts and artificial dyes. Safranin (also Safranin O or basic red 2) is a biological stain used in Histology and Cytology. Oil Red O ( Solvent Red 27, Sudan Red 5B, CI 26125, C26H24N4O is a Lysochrome (fat-soluble dye Diazo Congo red is the sodium salt of benzidinediazo-bis-1-naphtylamine-4-sulfonic acid (formula C32H22N6Na2O6S2 molecular Silver (ˈsɪlvɚ is a Chemical element with the symbol " Ag " (argentum from the Ancient Greek: ἀργήντος - argēntos gen Histochemistry refers to the science of using chemical reactions between laboratory chemicals and components within tissue. A commonly performed histochemical technique is the Perls Prussian Blue reaction, used to demonstrate iron deposits in diseases like Hemochromatosis. Haemochromatosis, also spelled hemochromatosis (see spelling differences) also called siderophilia
Recently, antibodies have been used to stain particular proteins, lipids and carbohydrates. Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily Proteins are large Organic compounds made of Amino acids arranged in a linear chain and joined together by Peptide bonds between the Carboxyl Lipids are broadly defined as any fat- Soluble ( lipophilic) naturally-occurring Molecule, such as fats oils waxes cholesterol sterols fat-soluble Carbohydrates (from ' Hydrates of Carbon ' or saccharides ( Greek σάκχαρον meaning " Sugar " are the most Called immunohistochemistry, this technique has greatly increased the ability to specifically identify categories of cells under a microscope. Immunohistochemistry or IHC refers to the process of localizing proteins in cells of a tissue section exploiting the principle of antibodies binding specifically Other advanced techniques include in situ hybridization to identify specific DNA or RNA molecules. Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known Ribonucleic acid ( RNA) is a Nucleic acid that consists of a long chain of Nucleotide units Digital cameras are increasingly used to capture histopathological images.
Interpretation
The histological slides are examined under a microscope by a pathologist, a medically qualified specialist. Pathology (from Greek grc πάθος pathos, "fate harm" and grc -λογία -logia) is the study and The diagnosis is formulated as a pathology report describing the histological findings and the opinion of the pathologist. In the case of cancer, this represents the tissue diagnosis required for most treatment protocols. Cancer (medical term Malignant Neoplasm) is a class of Diseases in which a group of cells display uncontrolled
See also
External links
- Immunohistochemistry - In Situ Hybridization
- Virtual Histology Course - University of Zurich (German, English version in preparation)
Dictionary
histopathology
-noun
- (biology) The microscopic study of tissue, especially of abnormal tissue as a result of disease
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