Histopathology: Subdivisions & Processes PDF

Subdivisions of Pathology Morphological Branches A. Histopathology or Anatomic Pathology 1. Surgical Pathology 2. Experimental Pathology 3. Forensic Pathology And Autopsy Work B. Cytopathology C. Haematology Non-morphological Branches A. Clinical Pathology B. Clinical Biochemistry C. Microbiology D....

Subdivisions of Pathology Morphological Branches A. Histopathology or Anatomic Pathology 1. Surgical Pathology 2. Experimental Pathology 3. Forensic Pathology And Autopsy Work B. Cytopathology C. Haematology Non-morphological Branches A. Clinical Pathology B. Clinical Biochemistry C. Microbiology D. Immunology F. Molecular Pathology Histopathology Examination of tissues to detect the changes in structure STEP1 due to disease process •Tissues are obtained by biopsies and excision of organs •Once the tissue is removed from the patient’s body, it is immediately preserved or fixedSTEP2 by putting it in a container of formalin (10% formaldehyde). •Tissue is processed in a special multistep way and the end result is very thin slices of stained tissue (4-6 microns) glued on a slide. SLIDE IS READY THIN SLICES OF TISSUE Routine Processing of Tissue for Histopathology Sequential Steps • Fixation • Dehydration • Clearing Processing • Impregnation • Embedding and blocking • Section cutting (Microtomy) • Mounting • Staining of Slides (H & E) Grossing--(appearance, measurements, pathological changes noted) and then bits of <ssue from areas of abnormality taken Tissue Processing Ttechnique of fixing the tissue into paraffin is called tissue processing • The main steps 1. Dehydration: Gradual removal of water from the tissue using ascending grades of ethyl alcohol(or other agents) to prevent tissue shrinking. 2.Clearing: Replacement of alcohol in tissue by clearing fluid like xylene, benzene, or acetone in which wax is soluble Embedding: Tissues are impregnated in paraAn-hardens the <ssue Cutting: Paraffin block are cut by microtome using metal knife, into thin sections (4 to 6 microns)This is done with a microtome Mounting: - Sections spread on the hot plate and mounted on glass slides. Staining: Tissue is "deparaffinized" to get the paraffin wax out of the tissue and allow water soluble dyes to penetrate the sections and then Staining done coverslip slide must be covered with a thin piece glass Automa<c <ssue processor Tissue embedding centre Rotary microtome Light Microscopy Immunohistochemistry (IHC) Immunohistochemistry (IHC) is a technique that exploits the specific binding between an antibody and antigen to detect and localize specific antigens in cells and tissue The tissue of interest is fixed and stained with antibodies specific to the antigens. Detection is accomplished by using enzymes such as horseradish peroxidase (HRP) or alkaline phosphatase (AP). Samples are visualized using microscopy. Immunohistochemistry (IHC) Routine Stain