HISTOLOGY

• What is microscopy used for?

  Magnification of objects
• Who created the cell theory?

  • Mattias Jacob Schleiden
  • Theodor Schwann
  • Established in 1838–1839
• What is the basic unit of living organisms according to cell theory?

  The cell
• Who extended the cell theory in 1885?

  Rudolf Virchow
• What does "omnis cellula e cellula" mean?

  All cells come from cells
• Who is considered a co-author of the cell theory?

  Jan Evangelista Purkinje
• What did Jan Evangelista Purkinje discover in 1825?

  The germinal vesicle of the bird egg
• What term did Purkinje coin in 1839?

  Protoplasm
• What are the additional components of the cell theory added in the 20th century?

  • Similar structure and organelles
  • Similar chemical composition
  • Universal genetic code
  • Similar cell division
  • Common evolutionary history
• What are the three groups of microscopes?

  Optical, electron, scanning probe
• What does an optical microscope use for image formation?

  Light (photons)
• What is the most commonly used microscope?

  Compound light microscope
• What are the parts of a compound light microscope?

  • Objective lens
  • Eyepiece
  • Light source
  • Condenser

  
• What is magnification?

  Making small objects seem larger
• What is resolution in microscopy?

  Distinguishing two objects from each other
• What happens if resolution is not increased with magnification?

  Images become blurry
• How do you calculate total magnification of a compound microscope?

  Objective lens power times eyepiece power

  
• If you have a x40 objective lens and a x2 eyepiece lens, what is the total magnification?

  $80$

  
• What are the main methods of histological investigation?

  • Light microscopy
  • Electron microscopy
• What are the types of histological preparation?

  • Smear
  • Specimen/sections
  • Imprint
  • Whole mount
• What is the purpose of fixation in histology?

  • Preserve biological structure
  • Prevent distortion or decomposition
• What is the most commonly used fixative in histology?

  10% formalin
• What does formalin do in tissue fixation?

  Cross-links proteins in the tissue
• What instrument is used for thin sectioning of tissue?

  Microtome
• How thick are the sections cut by a microtome?

  5–7 µm
• Why is staining required in histology?

  • Tissue contrast
  • Highlight features of interest

  
• What are the three basic staining methods?

  • Hematoxylin and Eosin (H&E)
  • Masson’s trichrome
  • Weigert’s elastic stain
• What is eosinophilic cytoplasm?

  Cytoplasm stained with acidic eosin
• What does basophilic cytoplasm indicate?

  Presence of ribonucleic acids
• What is the most common histological staining method?

  Hematoxylin and eosin (H&E)
• What is hematoxylin derived from?

  Logwood tree Hematoxylon campechianum
• When was hematoxylin first used by microscopists?

  Mid 1800s
• What are the types of special histological staining?

  • Masson’s trichrome
  • Orcein staining
  • Weigert Van Gieson staining
  • Silver impregnation
  • Iron hematoxylin
  • PAS staining
• What are common causes of artifacts in histological preparation?

  • Large spaces in tissue
  • Artificial spaces between cells
  • Unknown linear structures
  • Tissue tears and folds
• What can cause large spaces in tissue sections?

  Slight cracks in the sections
• What can lead to artificial spaces between cells?

  Loss of lipids or low-molecular-weight substances
• What can cause unknown linear structures in tissue?

  Precipitates from the stain
• What can cause curling artifacts in histological slides?

  Rough handling by forceps
• What can cause tissue tears and folds?

  Faulty blade during sectioning
• What can cause separation of connective tissue bands?

  Intralesional injection of anesthetic solution