Histopathology Laboratory Procedures Quiz

Outcome 3: Preparation of Clinical Specimens for Histological Examination

• This outcome describes the preparation of clinical specimens for histological examination.
• The process involves specimen acceptance, gross description, gross dissection, fixation, and tissue processing.
• Different sections of the document define various aspects of the preparation process, including definitions, specimen sources, pathways, preparation methods, and the role of the histotechnologist.

Section 1: Specimen Acceptance, Gross Description, and Gross Dissection

• Definitions: Histology, pathology, histopathology, histotechnical technique, histochemistry, and cytology are defined.
• Specimen Sources: Specimens may originate from autopsy, surgical tissue (whole organ, partial organ, excised tumor, excised cyst), curettage, amputation, products of conception, biopsy, or exfoliated cells.
• Pathway of a Surgical Specimen: The specimen's journey through the laboratory is outlined, describing stages like identification, accessioning, gross examination, preparation, pathologist viewing, staining, and consultation.
• Specimen Preparation: Methods for specimen preparation in the lab are listed .
• Tissue Examination Methods: Details of tissue examination, such as gross examination and use of brightfield microscopy.
• Role of the Histotechnologist: The histotechnologist's role in specimen entry, gross description, and gross dissection is explained.
• Specimen Accessioning: The steps involved in accurately recording specimen information to ensure proper identification and tracking are described.
• Gross Description: The process of gross examination and description of tissue specimens in the clinical laboratory are discussed with details.
• Gross Dissection: Details of the general procedure for gross dissection, relevant procedures, safety precautions, equipment, and specimen transportation are described.
• Equipment for Gross Dissection: A description and function of equipment like safety equipment, boards/trays, dissecting tools (scalpels, knives, scissors), and the use of marking reagents for dissection are noted.
• Safety Precautions: Safety precautions, such as proper use of protective gear and ventilation procedures are noted to avoid accidents and prevent exposure to harmful chemicals.

Section 2: Fixation

• Definition and Purpose of Fixation: Fixation is the preservation of tissue to prevent changes after death.
• Autolysis and Putrefaction: These are defined and their appearance described microscopically.
• Criteria for a Good Fixative: A good fixative preserves tissue morphology, maintains intracellular components, and prepares the tissue for staining.
• Causes of Improper Fixation: The document lists causes of improper fixation, such as inadequate fixative volume, incorrect fixative type, or prolonged fixation times
• Chemical Fixation Methods Different chemical fixation methods, such as vapor fixation, direct immersion, perfusion, are described.
• Factors Involved in Fixation: Various factors influencing fixation, such as temperature, pH, and speed of penetration are described.
• Classification of Chemicals: Chemicals used for fixation are classified based on their effect on proteins (additive or non-additive, coagulating or non-coagulating).
• Specific Fixatives and Their Properties: Properties of various chemicals such as formaldehyde, mercuric chloride, alcohol, picric acid, and acetic acid are described.
• Properties Unique to Formaldehyde: Formaldehyde's properties, including its use in fixation, tolerance to tissue, and reaction with proteins, are discussed.
• Compound and Microanatomical Fixatives: Definitions and properties of compound and microanatomical fixatives are provided.
• Specific Fixative Descriptions: Further detail on neutral buffered formalin, zinc formalin, Lillie's B-5 fixative, and Bouin's fluid, including their ingredients, properties, and applications.
• Secondary Fixation: Secondary fixation for various purposes and its importance are noted.
• Fixation Artifacts: The document defines fixation artifacts as structures that are not naturally present in living tissue.
• Pigments from Fixation: Specific pigments produced by various fixation procedures and how to remove them are identified.

Section 3: Principles of Tissue Processing

• Introduction to Processing: Initial steps of processing include dehydration, clearing, and infiltration, are described.
• Dehydration: Removal of water from tissue specimens
• Clearing Agents: The removal of alcohol (dehydration) and introduction of wax solvents (clearing).
• Xylene, Toluene, and Benzene: Comparing clearing agents based on their properties, speed, tolerance, etc.
• Xylene Substitutes: Alternatives to xylene, relevant information, and hazard data are presented.
• Universal Solvents: Types of solvents that are miscible with both water and paraffin, relevant information, and hazard data are presented.
• Factors Affecting Dehydration and Clearing: Various factors, such as the clearing agent, temperature, and the tissue, are noted.
• Problems in Dehydration and Clearing: Potential issues like incomplete wax infiltration and the brittleness of the tissue.
• Infiltration: Details on paraffin infiltration and its importance in handling tissue.
• Commercial Paraffin Waxes: Detailed information on several types of paraffin waxes and their important properties and additives.
• Factors Affecting Infiltration: Factors that influence the efficiency of infiltration (e.g., tissue size and type, clearing agent used).
• Vacuum Infiltration: The use of vacuum for more efficient infiltration and advantages of this technique..
• Automatic Tissue Processing This process is discussed with details on mechanisms like the Fluid Exchange Tissue Processor and modern automatic types.
• Tissue-Tek V.I.P. Vacuum Infiltration Processor: Specific information about this processor, including its components and functionalities.
• Recycling Reagents: Materials, procedures, and equipment for recycling tissue-processing reagents are explained.

Section 4: Decalcification

• Purpose of Decalcification: Removal of calcium salts from tissue specimens.
• Criteria for a Good Decalcifying Solution: Requirements for an ideal decalcifying agent.
• Procedure for Handling Tissue Requiring Decalcification: A step-by-step process for the application and removal of decalcifying agents
• Types of Bone Specimens: Different types of bone specimens and procedures for handling them.
• Decalcifying Fluids: Comparison of commercial decalcifying fluids like Nitric Acid, Formic Acid, and EDTA.
• Endpoint Determination: Testing procedures for decalcification completion .
• Surface Decalcification: This involves surface-only decalcification, which helps when dealing with tissues having localized calcification.