Microscopy in Pathology Labs
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Microscopy in Pathology Labs

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Questions and Answers

What is the resolving power of the human eye?

  • 200 nm
  • 7 nm
  • 0.2 µm (correct)
  • 10 µm

    • What is the typical size range of a eukaryote cell?

  • 1 mm - 5 mm
  • 100 µm - 500 µm
  • 50 nm - 100 nm
  • 10 µm - 50 µm (correct)

    • What is the thickness of cell membranes that need to be visualized?

  • 70 µm
  • 700 nm
  • 7 nm (correct)
  • 7 µm

    • What type of microscope uses visible light and glass lenses?

    <p>Light Microscope</p> Signup and view all the answers

    What is the highest resolution that visible light can provide?

    <p>0.2 µm</p> Signup and view all the answers

    Which type of microscopes are common for general observation of tissues and cells?

    <p>Light Microscope</p> Signup and view all the answers

    What does the high resolution of the transmission electron microscope (TEM) allow?

    <p>Viewing isolated particles magnified up to 400,000 times.</p> Signup and view all the answers

    How do denser areas or those that bind heavy metal ions appear in the images produced by TEM?

    <p>They appear darker (electron dense).</p> Signup and view all the answers

    What is the purpose of using compounds with heavy metal ions in TEM preparation?

    <p>To improve contrast and resolution.</p> Signup and view all the answers

    How is scanning electron microscopy different from transmission electron microscopy?

    <p>The electron beam passes through the specimen in TEM but not in SEM.</p> Signup and view all the answers

    In what way does the surface of samples differ between scanning electron microscopy and transmission electron microscopy?

    <p>In SEM, samples have a thin layer of heavy metal that reflects electrons; in TEM, they don't.</p> Signup and view all the answers

    What is a characteristic of images produced by scanning electron microscopy?

    <p>The surface of samples is covered with a thin layer of heavy metal that reflects electrons for imaging.</p> Signup and view all the answers

    What is the primary difference between light microscopes and electron microscopes?

    <p>Light microscopes have a lower resolving power than electron microscopes.</p> Signup and view all the answers

    Which type of electron microscope is used to study the surface structure of a sample?

    <p>Scanning Electron Microscope (SEM)</p> Signup and view all the answers

    What is the purpose of the condenser lens in a light microscope?

    <p>To focus the light onto the sample.</p> Signup and view all the answers

    What is the principle behind phase-contrast microscopy?

    <p>It relies on the refraction of light through different cellular structures.</p> Signup and view all the answers

    What is the purpose of fluorescent stains in fluorescence microscopy?

    <p>To enhance the contrast of the sample by making specific structures appear bright.</p> Signup and view all the answers

    Which of the following factors determines the total magnification of a light microscope?

    <p>The objective magnification and eyepiece magnification.</p> Signup and view all the answers

    What is the primary advantage of electron microscopes over light microscopes?

    <p>Electron microscopes can study the ultrastructure of cells and tissues.</p> Signup and view all the answers

    What is the main difference between Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM)?

    <p>TEM provides information about the internal structure of the sample, while SEM provides information about the surface structure.</p> Signup and view all the answers

    Why are unstained cells and tissue sections usually transparent and colorless?

    <p>They have a uniform refractive index throughout the sample.</p> Signup and view all the answers

    What is the primary limitation of light microscopes compared to electron microscopes?

    <p>Light microscopes use visible light, which has a longer wavelength.</p> Signup and view all the answers

    In scanning electron microscopy, the electron beam passes through the specimen.

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

    Transmission electron microscopy (TEM) allows isolated particles to be viewed in detail at magnifications up to 500,000 times.

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

    The electron-dense areas in TEM images appear bright.

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

    In TEM, the areas through which electrons pass appear dark (electron dense).

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

    Scanning electron microscopy is primarily used to study tissue sections embedded in resin.

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

    Heavy metal ions are added to the fixative or dehydrating solutions used in scanning electron microscopy to improve contrast.

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

    The resolving power of the human eye is 0.2 mm.

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

    The typical eukaryote cell is commonly between 10 and 50 mm in size.

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

    Cell membranes that need to be visualized are about 7 µm thick.

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

    Light microscopes use ultraviolet light and glass lenses for magnification.

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

    Electron microscopes have a resolving power of 0.2 nm.

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

    The wavelength of visible light limits the resolution of light microscopes.

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

    Electron microscopes have a higher resolution power than light microscopes because they use electron beams with shorter wavelength compared to visible light.

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

    The resolving power of a light microscope can be increased beyond 0.2 µm with digital methods of magnification.

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

    Fluorescence microscopy relies on the emission of shorter wavelength light when certain cellular substances are irradiated.

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

    Phase-contrast microscopy allows the examination of cells without fixation or staining by relying on the principle that light changes its direction when passing through cellular structures with different refractive indices.

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

    Scanning Electron Microscopes (SEM) are primarily used for studying the ultrastructure of tissues in ultrathin sections.

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

    Light microscopes contain only one main lens that is responsible for both gathering light and projecting the tissue image.

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

    The total magnification in a light microscope is the result of adding the objective magnification to the eyepiece magnification.

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

    Electron microscopes use glass lenses to focus electron beams and magnify images.

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

    Light microscopes rely on ultraviolet (UV) light to visualize tissue samples for histological studies.

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

    The resolving power of electron microscopes may be as large as 1 nm due to their use of visible light beams with longer wavelengths compared to electrons.

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

    Study Notes

    Microscopy

    • Microscopy is the technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye, i.e., objects that are not within the resolution range of the normal eye.
    • Microscopy refers to any type of examination in the pathology lab workflow that is conducted with a microscope.

    Resolving Power

    • The resolving power of the human eye is 0.2 mm (200 µm).
    • A typical eukaryote cell is commonly between 10 and 50µm in size (1 µm=10^-6 mm).
    • Cell membranes, which are about 7nm thick, require devices to magnify and visualize very small structures like cells and cell compartments.

    Types of Microscopes

    • There are two types of microscopes: Light Microscope and Electron Microscope.
    • Light microscopes, or optical microscopes, use visible light and glass lenses to magnify samples up to 1000 times, with a resolving power of 0.2 µm.
    • Electron microscopes are based on the very short wavelength of electrons and get a resolution power of 1 nm.

    Light Microscope

    • Light microscopes are essential for histological studies as they allow the visualization of cells and morphological features of tissues.
    • Light microscopes rely on glass lenses and visible light to magnify tissue samples.
    • Total magnification is the result of multiplying the objective magnification by the eyepiece magnification.

    Light Microscope Components

    • Light microscopes contain two main lenses: objectives and eyepieces (ocular).
    • Objective gathers the light that passes through the tissue, whereas the eyepiece projects the tissue image on the eye.

    Resolution and Magnification

    • Magnification and resolution power must not be confused, as resolution cannot be increased by magnification.
    • The limit of resolution of the light microscope is 0.2 µm (greatest magnification is x 1,400).

    Electron Microscope

    • Electron microscopes are used for studying the ultrastructure of cells and tissues, that is, the subcellular level organelles, membranes, and molecular complexes.
    • There are two types of electron microscopes: Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM).
    • TEM is used to study ultrastructure of tissues in ultrathin sections, while SEM is intended for the observation of surfaces.

    Electron Microscope Resolution

    • The resolving power of electron microscopes may be as small as 1 nm because they use electron beams instead of visible light.
    • Electron microscopes do not have glass lenses, they use magnets instead, that work as magnetic lenses by concentrating the electron beam emitted by an electron gun.

    Fluorescence Microscopy

    • Fluorescence microscopy is based on the principle that certain cellular substances emit light with a longer wavelength when irradiated with light of a proper wavelength.
    • Fluorescent compounds with affinity for specific cell macromolecules may be used as fluorescent stains.
    • Examples of fluorescent stains include Acridine orange, which binds both DNA and RNA, and DAPI, which specifically binds to DNA and is used to stain cell nuclei.

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    Description

    Explore the technical field of microscopy and its applications in pathology labs. Learn about using microscopes to view samples, identifying abnormalities, and conducting detailed examinations of fine structures and cell numbers.

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