Tissue Processing Techniques
43 Questions
5 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the purpose of clearing in tissue processing?

  • To stain the tissue for microscopy
  • To fix the tissue in a preservative solution
  • To dehydrate the tissue completely
  • To prepare the tissue for wax infiltration (correct)

    • What is the primary solvent used during the clearing stage of tissue processing?

  • Formalin
  • Ethanol
  • Acetone
  • Xylene (correct)

    • During the wax infiltration process, what replaces the last xylene in tissue samples?

  • Water
  • Acid
  • Molten wax (correct)
  • Alcohol

    • What is the function of the embedding station in tissue processing?

    <p>To fill metal molds with molten wax</p> Signup and view all the answers

    Which technique is primarily used for cutting thin sections of tissue specimens for microscopic examination?

    <p>Microtomy</p> Signup and view all the answers

    What is the typical thickness of tissue sections cut for microscopic examination?

    <p>4-6 μm</p> Signup and view all the answers

    Which staining procedure is commonly performed after section cutting to visualize tissue samples?

    <p>Hematoxylin-eosin (H&amp;E) staining</p> Signup and view all the answers

    What is the primary function of the rotary microtome in histology?

    <p>To obtain precise, serial sections of paraffin-embedded tissue</p> Signup and view all the answers

    Which method is commonly used for dehydrating tissue specimens in histopathological preparation?

    <p>Alcohol immersion</p> Signup and view all the answers

    What is the primary purpose of the wax infiltration process in tissue preparation?

    <p>To provide structural support for the tissue</p> Signup and view all the answers

    Which technique is used for cutting sections of paraffin-embedded tissue?

    <p>Microtomy</p> Signup and view all the answers

    Which staining procedure is utilized to enhance the visibility of specific cellular components under a microscope?

    <p>Hematoxylin and Eosin (H&amp;E)</p> Signup and view all the answers

    What is a key benefit of using alternative processing methods for tissues as opposed to classical techniques?

    <p>Ability to preserve nucleic acids better</p> Signup and view all the answers

    What is the primary purpose of dehydration in tissue processing?

    <p>To remove water so that alcohol can infiltrate the tissue</p> Signup and view all the answers

    Which of the following is NOT a recommended cutting technique for tissue blocks?

    <p>Blocks should be larger than 2 x 2 x 0.3 cm for easier handling</p> Signup and view all the answers

    What is the significance of marking the area to be cut with India ink?

    <p>To indicate the area for thin section cutting</p> Signup and view all the answers

    Which type of cassette would be most appropriate for small biopsies from gastrointestinal endoscopy?

    <p>Cassette for small specimen like skin biopsy</p> Signup and view all the answers

    What step follows dehydration in the tissue processing sequence?

    <p>Clearing the tissue</p> Signup and view all the answers

    What is the recommended ratio of specimen size to fixative volume?

    <p>1:10</p> Signup and view all the answers

    What is a negative effect of formaldehyde on biological samples?

    <p>It induces adverse symptoms in individuals exposed to it</p> Signup and view all the answers

    What should be done if there is a delay between tissue removal and fixation in formalin?

    <p>Keep the tissue refrigerated until fixation.</p> Signup and view all the answers

    Which of the following correctly describes the optimal thickness of tissue sections?

    <p>Sections should ideally be about 2-3 mm thick</p> Signup and view all the answers

    What process is crucial for embedding the dehydrated tissue samples?

    <p>Infiltration with wax or resin</p> Signup and view all the answers

    When is it acceptable to send tissue fresh directly from the operation theatre?

    <p>During office hours if necessary.</p> Signup and view all the answers

    Why is it important to remove sutures, clips, and bone fragments before processing tissue?

    <p>To prevent contamination of other samples</p> Signup and view all the answers

    What is the purpose of using 10% neutral buffered formalin in specimen fixation?

    <p>To maintain the life-like state of tissues.</p> Signup and view all the answers

    What is the recommended action for macroscopic examination of tissues?

    <p>All relevant dimensions and identification details must be recorded</p> Signup and view all the answers

    What should NOT be done with specimens that are fixed in formalin?

    <p>Fix them with spray fixative.</p> Signup and view all the answers

    How should body fluid samples be preserved if they cannot be delivered immediately to the laboratory?

    <p>Refrigerate at 2-8°C.</p> Signup and view all the answers

    What is the implication of improper fixation for tissue specimens?

    <p>It can result in adverse effects on specimen integrity.</p> Signup and view all the answers

    In what scenario should a cervical smear be prepared?

    <p>By labeling the slide with the patient’s identification.</p> Signup and view all the answers

    What is critical in the samplings during FNAC (Fine Needle Aspiration Cytology)?

    <p>Labeling slides correctly with patient identification.</p> Signup and view all the answers

    What is the first step after collecting a sample in histopathology?

    <p>Immerse the sample in fixative immediately.</p> Signup and view all the answers

    What is the optimal tissue to formalin ratio for very large specimens to ensure proper fixation?

    <p>1:5</p> Signup and view all the answers

    Which of the following fixatives is known for producing mild cross linkages compared to others?

    <p>Neutral buffered formalin</p> Signup and view all the answers

    What thickness should tissues be sliced to in order to achieve adequate fixation?

    <p>3 mm</p> Signup and view all the answers

    What is one of the key advantages of using formalin as a fixative?

    <p>Good preservation of morphological structures</p> Signup and view all the answers

    What should be done with the specimen container lid before transporting specimens?

    <p>Ensure it is securely fastened</p> Signup and view all the answers

    What effect does raising the ambient temperature have on the fixation process?

    <p>Increases the rate of fixation</p> Signup and view all the answers

    Which of the following represents the appropriate pH range for a formalin solution?

    <p>5 to 7</p> Signup and view all the answers

    What is the ideal storage condition for specimens in formalin prior to laboratory transport?

    <p>At room temperature</p> Signup and view all the answers

    Which of these tissues typically requires extended fixation time?

    <p>Spleen</p> Signup and view all the answers

    What is the purpose of forming cross linking methylene bridges between proteins during fixation?

    <p>Stabilizes the proteins in situ</p> Signup and view all the answers

    Study Notes

    Tissue Processing

    • Tissue processing includes a series of steps to prepare tissue samples for microscopic examination.
    • Clearing: This step makes the tissue transparent using xylene, allowing for proper wax infiltration.
    • Wax Infiltration: Xylene is replaced with molten wax, which soaks into the tissue.
    • Embedding: The wax-infiltrated tissue is oriented in a mold, filled with molten wax, and cooled to solidify, creating a block.
    • Section Cutting: Thin slices of the tissue block are cut using a microtome, typically at 4-6 micrometers thick.
    • Staining: The sections are mounted on slides and stained, often with hematoxylin and eosin (H&E) for visualization.

    Sample Collection and Transport

    • Tissues are immediately immersed in 10% neutral buffered formalin (fixative) in a closed container with patient identification.
    • The recommended specimen size to fixative volume ratio is 1:10.
    • Samples should be sent to the laboratory as soon as possible.
    • Samples in formalin should not be stored in a refrigerated area as this slows down the fixation rate.

    Formalin Fixation

    • Formalin is used to preserve the tissue in a life-like state as possible.
    • A delay between tissue removal and formalin immersion can affect the specimen integrity.
    • Proper specimen fixation requires:
      • An appropriately sized container.
      • Adequate volumes of formalin (1:5 for large specimens, 1:10 for small specimens).
      • Matching specimen pot and request card details.
      • Securely fastened lid.
    • Specimens in formalin should be stored at room temperature until transported to the laboratory.

    Fixation Benefits

    • Preservation: Keeps the tissue and cells as life-like as possible, preventing shrinking or swelling.
    • Putrefaction Prevention: Prevents bacterial decomposition and autolysis (self-destruction).
    • Stabilization: Protects tissues and cells from the effects of processing and staining.

    Aldehyde Fixatives

    • The most common aldehyde fixatives are:
      • Neutral buffered formalin.
      • Glutaraldehyde.
      • Paraformaldehyde.
    • These fixatives form chemical bonds (cross-links) between proteins, stabilizing the tissue structure.

    Fixation Time

    • Fixation time depends on the specimen size.
    • Specimens should be sliced to a maximum thickness of 3 mm for proper and consistent fixation.
    • Routine fixation time is approximately 24-48 hours at room temperature for tissues like lymph nodes, skin, and bone marrow.
    • Dense tissues like spleen may require extended fixation.
    • Increasing the ambient temperature can accelerate fixation.
    • Formalin solution pH typically ranges between 5 and 7.

    Formaldehyde Advantages

    • Inexpensive.
    • Easy to use.
    • Rapid tissue penetration.
    • Good preservation of morphological structures.
    • Compatible with downstream histological applications.

    Formaldehyde Disadvantages

    • Negative effects on nucleic acids.
    • Formaldehyde released in the air can cause watery eyes, burning sensations, coughing, wheezing, nausea, and skin irritation.

    Macroscopic Examination

    • Pathology involves both macroscopic and microscopic examination of tissues.
    • The macroscopic examination considers the clinical and radiographic history.
    • Specimens are placed on a cutting board, and the following information is recorded:
      • Type of specimen.
      • Included structures.
      • Dimensions.
      • Weight.
      • Shape.
      • Color.
      • Identification of surgical margins.
    • Areas of interest within the tissues are cut into small pieces, numbered, and labeled.

    Cutting Suggestions

    • Do not make blocks too thick.
    • Blocks should be no larger than 2 x 2 x 0.3 cm.
    • Do not overcrowd lymph nodes in one cassette.
    • Remove sutures, clips, and bone fragments.
    • Cut blocks with flat surfaces and squared corners.
    • The length of the tissue block should be no more than 20 mm, and the thickness ideally about 2-3 mm.
    • Mark areas to be cut with India ink (skin, epithelium, vessels, etc.).

    Cassette Types

    • Standard cassette: General use.
    • Small biopsy cassette: For liver biopsies.
    • Small specimen cassette: For small skin biopsies or biopsies from gastrointestinal endoscopy.
    • High circulation cassette: For specimens like adipose tissue that need enhanced fluid circulation during processing.

    Tissue Processing Machines

    • Modern tissue processors have a chamber where specimens are held.
    • Solutions are pumped in and out of the chamber during processing.

    Dehydration

    • This step removes water from the tissue by immersing it in a series of increasing ethanol concentrations until 100% alcohol.
    • This prepares the tissue for wax infiltration.

    Histopathological Examination

    • The study of the signs of disease using microscopic examination of biopsies or surgical specimens.
    • Sections are stained to visualize different tissue components under a microscope.
    • Cytological samples include aspirates, smears, swabs, and body fluids.
    • Tissue samples include biopsies and surgical specimens.

    Microscopic Examination

    • The microscopic examination of tissues is used to diagnose diseases by identifying characteristic features.
    • It allows pathologists to compare changes in the cellular structure between healthy and diseased tissues.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Pathology Tutorial 1 PDF

    Description

    This quiz covers the critical steps involved in tissue processing for microscopic examination, including clearing, wax infiltration, embedding, section cutting, and staining. You will also learn about proper specimen collection and transport methods. Test your knowledge on these essential histological techniques!

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser