Histology Techniques and Methods
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Questions and Answers

What is the purpose of using a series of ethanol solutions in tissue preparation?

  • To remove wax from the specimen
  • To replace water in the specimen with ethanol (correct)
  • To section the tissue
  • To stain the specimen

    • What is the term for the process of displacing ethanol with a solvent that is miscible with both ethanol and paraffin wax?

  • Embedding
  • Dehydration
  • Staining
  • Clearing (correct)

    • What is the typical temperature at which a histological wax is liquid?

  • 60°C (correct)
  • 80°C
  • 70°C
  • 50°C

    • What is the purpose of the microtome in tissue preparation?

    <p>To slice thin tissue sections</p> Signup and view all the answers

    What is the purpose of staining in tissue preparation?

    <p>To make the tissue conspicuous and distinguishable</p> Signup and view all the answers

    What is the term for the process of enclosing the tissue in an embedding mould?

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

    What is the primary purpose of fixation in slide preparation?

    <p>To preserve tissue structure</p> Signup and view all the answers

    What is the main component of the media layer in elastic arteries?

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

    What is the recommended formalin-to-specimen volume ratio for optimal fixation?

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

    Which layer of the muscular artery is well-developed and has a prominent internal elastic lamina?

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

    What is the purpose of biopsy and aspiration?

    <p>To acquire tissue samples for study</p> Signup and view all the answers

    What is the diameter range of larger or muscular arterioles?

    <p>100-50 µm</p> Signup and view all the answers

    Why is it important to handle fresh tissue specimens carefully?

    <p>Because they can easily be damaged during removal</p> Signup and view all the answers

    What is the main function of arterioles?

    <p>To regulate peripheral vascular resistance</p> Signup and view all the answers

    What is the purpose of in vitro histology?

    <p>To study tissues outside of the body</p> Signup and view all the answers

    What is the layer of the arteriole that is made up of a thin network of collagen fibers?

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

    What is the characteristic feature of the media layer in muscular arteries?

    <p>Presence of smooth muscles</p> Signup and view all the answers

    What is the purpose of dehydration in tissue preparation?

    <p>To remove water from tissue samples</p> Signup and view all the answers

    What is the next structure in the blood vessel system after the terminal arterioles?

    <p>Capillary plexus</p> Signup and view all the answers

    What is the common fixative used for most tissue samples?

    <p>10% neutral buffered formalin</p> Signup and view all the answers

    What is the characteristic feature of the adventitia layer in elastic arteries?

    <p>It is relatively thin with a greater proportion of elastic fibers</p> Signup and view all the answers

    What is the time frame for adequate fixation of tissues?

    <p>6-24 hours</p> Signup and view all the answers

    What is autoradiography used for?

    <p>To determine where radioactively labeled compounds are in a cell</p> Signup and view all the answers

    What is the purpose of enzyme histochemistry?

    <p>To localize cellular structures using specific enzymatic activity</p> Signup and view all the answers

    What is the function of the enzymes secreted by osteoclasts?

    <p>To digest and remove bone matrix</p> Signup and view all the answers

    What is the main component of organic bone matrix?

    <p>Type 1 collagen</p> Signup and view all the answers

    What can cause swelling and shrinkage of tissue components?

    <p>Poor fixation and/or dehydration techniques</p> Signup and view all the answers

    What is a common artifact in tissue samples?

    <p>Stain precipitate</p> Signup and view all the answers

    What is the function of the periosteum?

    <p>To facilitate bone formation and repair</p> Signup and view all the answers

    What is the main component of inorganic bone matrix?

    <p>Hydroxyapatite crystals</p> Signup and view all the answers

    What is a characteristic of neurons?

    <p>They are independent anatomic and functional units</p> Signup and view all the answers

    What are the two main types of cells in the nervous system?

    <p>Nerve cells and glial cells</p> Signup and view all the answers

    What type of bone is found in the inner part of bones and is more abundant in the epiphysis?

    <p>Cancellous bone</p> Signup and view all the answers

    What is the structure formed by the parallel layers of calcified type 1 collagen in compact bone?

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

    What is a property of the nervous system?

    <p>It responds to various types of stimuli</p> Signup and view all the answers

    What is the function of the endosteum?

    <p>To facilitate bone formation and repair</p> Signup and view all the answers

    What is the abbreviation for Peripheral Nervous System?

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

    What is the outer covering of a bone?

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

    Study Notes

    Histological Techniques

    • Histological techniques are procedures used in the acquisition, processing, and viewing of histologic samples.
    • If well carried out, they yield quality results.

    Biopsy and Aspiration

    • Biopsy is a method of acquiring tissue samples for study.
    • A small portion of the specimen is excised with a sharp blade or a fluid specimen is aspirated with the aid of a needle.
    • Fresh tissue specimens can come from various sources and can be easily damaged during removal from the patient or experimental animal.
    • They should be handled carefully and fixed as soon as possible after dissection.

    Fixation

    • Slide preparation begins with the fixation of the tissue specimen to preserve tissue structure.
    • The purpose of fixation is to prevent tissue autolysis and putrefaction.
    • For best results, biological tissue samples should be transferred into a fixative immediately after collection.
    • Most specimens are fixed in 10% neutral buffered formalin.
    • The optimum formalin-to-specimen volume ratio should be at least 10:1 (e.g., 10ml of formalin per 1cm3 of tissue).
    • This will allow most tissues to become adequately fixed within 6-24 hours.

    Dehydration

    • Water in a specimen must be removed before it can be infiltrated with wax.
    • Dehydration is carried out by immersing specimens in a series of ethanol (alcohol) solutions of increasing concentration.
    • Ethanol is miscible with water and progressively replaces the water in the specimen.

    Clearing

    • Wax and ethanol are largely immiscible.
    • A solvent miscible with both ethanol and paraffin wax is used to displace the ethanol in the tissue.
    • This stage in the process is called "clearing" and the reagent used is called a "clearing agent".

    Wax Infiltration

    • The tissue can now be infiltrated with a suitable histological wax.
    • A typical wax is liquid at 60°C and can be infiltrated into tissue at this temperature.
    • It is actually done in an oven.

    Embedding

    • The process of enclosing the tissue in the embedding mould.
    • The mould is filled with melted wax and the specimen is placed on it.
    • The embedding mould is used to orient the specimen well.

    Sectioning and Mounting

    • A microtome is used to slice thin tissue sections off the block in the form of a ribbon.
    • The microtome can be pre-set to cut different thicknesses.

    Staining

    • Stains are dyes applied to tissue specimens to make them conspicuous and distinguishable from one another.
    • A sample of culture is mounted on the slide for viewing.

    Autoradiography

    • Autoradiography is a technique that uses photographic film to determine where within a cell a specific radioactively labeled compound is at the time the cell is fixed and sectioned for microscopy.

    Enzyme Histochemistry

    • This is a method for localizing cellular structures using specific enzymatic activity.
    • Examples of enzymes detectable are phosphatases, dehydrogenases, and peroxidase.

    Artifacts

    • Artifacts are the result of changes in a tissue's structure or the addition of new structure.
    • They include swelling and shrinkage of tissue components, wrinkles in sections, tears in sections, air bubbles, and dust.
    • These can result from poor fixation and/or dehydration techniques, poor sectioning technique, or poor technique during mounting of sections.

    Nervous Tissue

    • The nervous system is made up of two cell types: nerve cells (neurons) and glial cells (neuroglia).
    • Neurons are excitable, independent anatomic and functional units with complex morphological characteristics.

    Arteries

    • Arteries are classified into two types: elastic arteries and muscular arteries.
    • Elastic arteries have a relatively thin adventitia with a greater proportion of elastic fibers.
    • Muscular arteries have a thicker adventitia with a smaller proportion of elastic fibers.

    Arterioles

    • Arterioles are the main regulators of peripheral vascular resistance.
    • Contraction and relaxation of the smooth muscles present in the walls of the arterioles can alter the peripheral vascular resistance (or blood pressure) and the blood flow.

    Capillaries

    • Terminal arterioles are continued into a capillary plexus that pervades the tissue supplied.
    • Capillaries have a thin wall that allows for the exchange of substances between the blood and the tissue.

    Bone Matrix

    • Bone matrix consists of two components: organic components (type 1 collagen, chondroitin sulfate) and inorganic components (calcium and phosphorus forming hydroxyapatite crystals).
    • The bone matrix is acidophilic in H&E section and shows the collagen type 1 and the bone cells.
    • The bundles of collagen in the matrix form parallel layers called bone lamellae.

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    Histology 1st Semester PDF

    Description

    This quiz covers the various methods and techniques used in histology, including in vitro studies, histological techniques, and biopsy and aspiration methods.

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