Microscope

• What is the primary tool used in the study of histology?

  Microscope
• Microscope is an optical device that produces an ENLARGED IMAGE and enhances CONTRAST for resolving details.
• Which type of microscope transmits light through 3 glass lenses?

  Light microscope
• In a conventional light microscope, light first focused on a WHAT by a SUBSTAGE CONDENSER LENS?

  Stained specimen
• In a conventional light microscope, after focusing on a stained specimen, it then passes through it and then through what type of lens next?

  Objective lens
• Which lens of a conventional light microscope MAGNIFIES and PROJECTS the illuminated specimen to OCULAR LENS?

  Objective lens
• Ocular lens: further magnifies the image and projects it to the eye of the viewer or a photographic plate.
• In a conventional light microscope, most tissues are COLORLESS, so COLOR DYES serves as stains that differentially ABSORB light so that structures in specimens may be distinguished.
• A transmission electron microscope transmits a beam of what through an ULTRATIHIN SECTION of tissue that has been cut via an ultramicrotome?

  Electrons
• Several COILED electromagnetic lenses deflect electrons and use the same principle as that of light microscope lenses to condense, focus, and magnify images.
• Electrons from a heated what or cathode are drawn toward an anode within a vacuum column?

  tungsten filament
• Electrons are not visible to the naked eye, so FLUORESCENT SCREEN or PHOTOGRAPHIC PLATE records the image as a black and white electron micrograph.
• What is the advantage of TEM?

  great resolving power
• HEMATOXYLIN or EOSIN: blue?

  Hematoxylin
• HEMATOXYLIN or EOSIN: cationic stain?

  Hematoxylin
• HEMATOXYLIN or EOSIN: binds to ANIONIC or negatively charged?

  Hematoxylin
• HEMATOXYLIN or EOSIN: binds to BASOPHILIC sites in tissue sections?

  Hematoxylin
• HEMATOXYLIN or EOSIN: pink?

  Eosin
• HEMATOXYLIN or EOSIN: an anionic stain?

  eosin
• HEMATOXYLIN or EOSIN: binds to ACIDOPHILIC or positively charged tissue components?

  eosin
• Tissues in Electron microscopy are stained with what?

  heavy metals
• Give 2 examples of heavy metals?

  lead citrate and uranyl acetate
• What are the 2 major kinds of microscope?

  Light and electron microscope
• Resolving power: ability to discriminate two points that are close together
• A conventional light microscope uses what illumination?

  Bright-field
• What is the resolving power of light microscope?

  0.2 micrometers
• Most cells absorb very little light, so STAINING is needed to increase light ABSORPTION.
• Brightfield microscopy: specimen is examined with ordinary light passing through the preparation.
• Condenser: collects and focuses a CONE of light that illuminates the tissue slide on the stage
• Objective lenses: enlarge and project the illuminated image of the object toward the eyepiece
• 4x: observing a large area (field) of the tissue at low magnification
• 10x: medium magnification of a smaller field
• 40x: high magnification of more detailed areas
• Eyepiece or Ocular: magnify this image another X10 and project it to the viewer, yielding a total magnification of X40, X100, or X400
• Fluorescence microscopy: tissues are stained with a FLUORESCENT DYE that binds to specific component of the tissue and are irradiated with UV LIGHT.
• Phase-contrast microscopy: uses a lens system that produces visible images from TRANSPARENT objects and, importantly, can be used with LIVING, CULTURED cells
• In Brightfield microscopy, without FIXATION and staining, only 2 PIGMENT CELLS can be seen.
• In phase-contrast microscopy CELL BOUNDARIES, nuclei, and cytoplasmic structures with different REFRACTIVE INDICES affect in-phase light differently and produce an image of these features in all the cells.
• Differential Interference Microscope: Cellular details are HIGHLIGHTED in a different manner using NOMARSKI OPTICS.
• What type of microscopy is widely used to observe LIVE CELLS grown in TISSUE CULTURE?

  Phase-contrast with or without differential interference