Tissue Fixation in Biology
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Questions and Answers

What is the primary objective of tissue fixation?

  • To preserve the chemical composition of the sample
  • To preserve the cells and tissue components as close to normal as possible (correct)
  • To increase the mechanical strength of the sample
  • To prevent extrinsic damage to the sample

    • How does fixative typically protect a sample from damage?

  • By altering the cells or tissues on a molecular level
  • By killing any microorganisms that may be present in the sample
  • By increasing the mechanical stability of the sample
  • By disabling intrinsic biomolecules that would otherwise damage the sample (correct)

    • What is the purpose of the additional processing steps and final analyses that are planned?

  • To further preserve the morphology of the sample
  • To increase the mechanical strength of the sample
  • To chemically mask the protein targets for immunohistochemistry
  • To determine the appropriate fixation method to use (correct)

    • How does heat fixation differ from other fixation methods?

    <p>It preserves overall morphology but not internal structures</p> Signup and view all the answers

    What is the effect of prolonged fixation on immunohistochemistry analysis?

    <p>It chemically masks the protein targets, preventing antibody binding</p> Signup and view all the answers

    What is the purpose of mixing the sample with water or physiological saline in heat fixation?

    <p>To evenly spread out the sample for fixation</p> Signup and view all the answers

    Which of the following is the most common staining technique used in routine histological analysis?

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

    What is the primary function of the counterstain in a staining procedure?

    <p>To differentiate between different cellular structures</p> Signup and view all the answers

    Which of the following is a characteristic of the Leishman stain?

    <p>It stains the nuclei blue and the cytoplasm pink</p> Signup and view all the answers

    What is the primary purpose of staining biological tissues for microscopic examination?

    <p>To highlight specific cellular components or structures</p> Signup and view all the answers

    Which of the following factors can influence the intensity of staining in a tissue section?

    <p>The concentration of the target tissue</p> Signup and view all the answers

    Which of the following is a characteristic of an artifact in a microscopic tissue preparation?

    <p>It is a distortion or alteration caused by the preparation process</p> Signup and view all the answers

    Which of the following is a primary component of the Leishman stain?

    <p>Methylene blue</p> Signup and view all the answers

    What is the primary function of the fixative used in tissue preparation?

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

    Which of the following is a characteristic of natural dyes used in tissue staining?

    <p>They are rarely used in modern histological techniques</p> Signup and view all the answers

    What is the primary purpose of using a counterstain in a tissue preparation?

    <p>To differentiate between different cellular structures</p> Signup and view all the answers

    What is the primary purpose of the fixation process in tissue preparation?

    <p>To stabilize the proteins, nucleic acids, and microsubstances of the tissue in a state as close to living tissue as possible</p> Signup and view all the answers

    Which factor is least important in determining the effectiveness of chemical fixation?

    <p>The type of microscopy technique to be used for analysis</p> Signup and view all the answers

    What is the purpose of the clearing step in tissue processing?

    <p>To replace the ethanol in the tissue sample with an organic solvent miscible with both alcohol and the embedding medium</p> Signup and view all the answers

    Which of the following statements is true regarding the embedding process in tissue preparation?

    <p>The embedding medium provides support and prevents distortion of the tissue during sectioning</p> Signup and view all the answers

    What is the typical thickness range of tissue sections cut for transmission electron microscopy?

    <p>0.1-0.5 micrometers (µm)</p> Signup and view all the answers

    Which of the following statements is true regarding the mounting of tissue sections?

    <p>Sections are floated in a water bath before being mounted onto glass slides</p> Signup and view all the answers

    What is the primary advantage of using the freezing method for tissue fixation?

    <p>It provides rapid fixation results</p> Signup and view all the answers

    Which of the following statements is true regarding the duration of chemical fixation?

    <p>A general rule is to allow 1 hour of fixation per 1 millimeter of tissue thickness</p> Signup and view all the answers

    What is the purpose of the dehydration step in tissue processing?

    <p>To remove water from the tissue and replace it with a series of increasingly concentrated alcohol solutions</p> Signup and view all the answers

    Which of the following factors should be considered when selecting the embedding medium for tissue preparation?

    <p>The type of tissue and the intended microscopy technique</p> Signup and view all the answers

    Fixation is the final step in the process to prepare a sample of biological material for microscopy analysis.

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

    Fixatives are non-toxic to common microorganisms like bacteria.

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

    The purpose of fixation is solely to increase the mechanical strength of cells and tissues.

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

    Heat fixation is commonly used for multicellular organisms like plants.

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

    Quick fix using cold formalin for around 24 hours is primarily used in immunohistochemistry to enhance antibody binding.

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

    Fixatives do not alter cells or tissues at a molecular level.

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

    Leishman stain is mainly used for staining DNA in the cell nucleus.

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

    Acidic dyes bind with negatively charged basophilic tissue.

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

    Hematoxylin stains RNA-rich portions of the cytoplasm pink.

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

    The nuclei take up a pink stain with Leishman stain.

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

    Eosin is considered a primary dye in H&E staining.

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

    Neutral dyes are commonly extracted from plants and animals.

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

    Chelating dyes are used based on tissue geometry.

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

    Artifacts can occur due to extraneous factors before fixation only.

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

    Natural dyes are mostly petroleum derivatives.

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

    Heat fixation is typically used in routine histological analysis.

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

    In tissue processing, dehydration removes all water from the tissue by using diluted alcohol solutions.

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

    The pH for ultrastructure preservation during fixation should be buffered between 7.2 to 7.4.

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

    Hypertonic fixatives result in cell swelling and poor fixation.

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

    Embedding for electron microscopy commonly uses paraffin wax as the embedding medium.

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

    The thickness of tissue sections cut for light microscopy using a steel knife is typically 5-10 µm.

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

    Tissue freezing is a method that provides fine details but does not give rapid results.

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

    An ideal thickness for tissue specimens during fixation is between 1-4 cm.

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

    Embedding for electron microscopy involves using molds to harden the tissue samples.

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

    Chemical fixation occurs within milliseconds and allows preservation of structures in their native state.

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

    FFPE tissues can only be stored at low temperatures to prevent degradation.

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

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