Pathology

• Pathology

  Pathos = suffering (disease), logos = study (science). Pathology literally translates to the study of suffering. As applied to modern medicine, it is the study of disease. Pathology is the science that investigates the causes of diseases, developmental stages, and structural and functional changes caused by diseases in the relevant tissue or organ. A pathologist is a person who specializes in pathology.
• Purpose of Pathology
• Etiology


  Refers to the underlying causes and modifying factors responsible for the initiation and progression of disease
• Morphology

  Gross or micro changes in cells, tissues, and organs
• Pathogenesis

  Refers to the mechanisms of development and progression of disease, accounting for the cellular and molecular changes that give rise to specific functional and structural abnormalities characterizing any particular disease
• Clinical significance


  To reveal clinically important points by examining functional changes that are reflections of morphological (structural) changes
• The foundation of modern pathology is understanding the cellular and molecular abnormalities that cause diseases
• The field of pathology is devoted to understanding the causes of disease and the changes in cells, tissues, and organs associated with disease, giving rise to presenting signs and symptoms in patients
• Etiology and pathogenesis of disease are essential for understanding disease and are the basis for developing rational treatments and effective preventive measures
• Responsibilities of a Pathologist
• Responsibilities of a Pathologist

  Use a variety of morphological, molecular, and other techniques to define the biochemical, structural, and functional changes in cells, tissues, and organs in response to injury
• Diagnosis


  Examining and diagnosing tissues and organs thought to be diseased
• Treatment

  Guidance in determining the form of treatment and determination of the degree of effectiveness
• Screening


  Examination of people at risk to detect common diseases before significant impairment occurs
• Sample types

  • Biopsy
  • Tissues and organs removed/disposed surgically
  • Smear preparations
  • Tissue samples from autopsy
• Pathology Techniques

  Fixation: Maintain the cells in their living state and prevent the tissue from decaying. Tissues are alive when they leave the human body and show morphological signs of the disease they carry. After some time, they are autolyzed by the effect of bacteria and the dig
• Pathology techniques

  Fixation: Maintain the cells in their living state and prevent the tissue from decaying. Tissues are alive when they leave the human body and show morphological signs of the disease they carry (if any). After some time, they are autolyzed by the effect of bacteria and the digestive enzymes they contain, lose their morphological features and become unusable in diagnostic examinations.
• Special liquids used for fixation

  • 10% formaldehyde solution
  • 80% ethyl alcohol
  • Bouin solution
  • Zenker solution
• Liquids used for fixation should be in a solution 10-20 times their volume and wait at least 4 hours (for small tissues). Samples of body fluids to be sent in the tube should be mixed with the fixative in half.
• Pathological examination

  1st examination - Macroscopic: Examining the material with the naked eye and sampling from the places that are thought to best reflect the pathology. 2nd Microscopic examination: Dehydration, Hardening, Transparency, Paraffinization, Block preparation, Section Preparation, Painting
• Tissue processing


  It is a procedure that is performed during the operation and guides the operation. It takes 10-15 minutes. In order to take thin sections from the tissues, they are frozen at -20 degrees with the help of a cryostat device. Sections are made from frozen tissue. Paint is made by the accelerated method. Examination of tissue under the microscope.
• Dehydration-Hardening


  Tissue must be firm in order to obtain a thin section. The water of the tissue is removed and replaced with alcohol. 70%, 80%, 90%, 96%, and 100% (absolute) alcohols are each left for at least one hour.
• Transparency


  Taking the alcohol in the tissue and replacing it with solutions such as xylene or toluene (tissues are kept in this solution for 30-45 minutes). Xylene dissolves the fats and makes the tissue transparent.
• Paraffinization


  It is kept in paraffin at 58-60°C for 4 hours. Paraffin replaces xylene. Tissues become transparent and cuttable.
• Block preparation (Burying)


  Blocks are prepared by embedding the hardened tissues in paraffin with the cut side to the bottom.
• Section preparation

  Thin sections of 4-6 microns are obtained from paraffin blocks with special instruments called microtomes. Hematoxylin+Eosin (H+E) is the most preferred dye in daily studies. The cytoplasm of the cells is pink and the nuclei are blue-violet. Examination is done under a light microscope.