MIDTERM

• Bright-Field Microscopy


  Stained tissue is examined with ordinary light
• Optical Components


  • Condenser: focuses the light
  • Objectives: enlarging and projecting
  • Eyepiece: projecting into the retina
• Resolving Power


  Critical factor in obtaining a crisp, detailed image
• Virtual Microscopy


  Used for the study of bright-field microscopic preparations using a digital device
• Fluorescence Microscopy


  Tissue sections are irradiated with ultraviolet (UV) light
• Fluorescence


  Emit light with a longer wavelength
• Phase-Contract Microscopy


  Produce visible images from transparent objects
• Differential Interference Contrast Microscopy


  Produces a 3D image of cells
• Confocal Microscopy


  Produces a 3D image using a laser
• Polarizing Microscopy


  Normal light passes through a polarizing filter
• Birefringence


  The ability to rotate the direction of vibration of polarized light
• Transmission Electron Microscope (TEM)


  Allows isolated particles magnified 400,000 times to be viewed in detail
• Scanning Electron Microscopy


  Provides high resolution like TEM, but light does not pass through the specimen
• Preparation of Tissues for Study

  1. Fixation

  2. Dehydration

  3. Clearing

  4. Infiltration

  5. Embedding

  6. Trimming
• Fixation


  To preserve and prevent degradation
• Fixative


  Cross-linking compound
• Dehydration


  Goes through a series of alcohol solutions that removes all water
• Clearing


  Use of Saline to remove dehydration agents
• Infiltration


  Tissue is placed in melted paraffin until it infiltrates with the substance
• Embedding


  Paraffin-tissue is placed in a small mold to harden
• Trimming


  Tissue is sectioned using a microtome, 2 to 10 Micrometer
• Characteristic Features of Epithelial Tissue

  • Columnar
  • Squamous
  • Cuboidal
• Lamina Propia


  CT that underlies the epithelia lining of digestive, respiratory, and urinary systems
• Papillae


  Small evaginations
• Basal Pole


  Contacts the ECM and CT
• Apical Pole


  Opposite end, usually facing space
• Basement Membrane


  A thin, extracellular felt-like sheet of macromolecules
• Basal Lamina


  Thin, electron-dense, sheet like layer of fine fibrils
• Reticular Lamina


  More diffuse and fibrous
• Type III collagen


  Contained by the reticular lamina
• Type VII collagen


  Anchoring fibrils
• Specialization of the Apical Cell Surface

  • Microvilli
  • Stereocilia
  • Cilia
• Microvilli


  Array of projections specialized for absorption
• Stereocilia


  Increase the cells' surface area, line the male reproductive system, longer and less motile than Microvilli, show distal branching
• Cilia


  Long, highly motile apical structures, larger than Microvilli, contains internal arrays of microtubules not microfilaments
• Classification and Distribution of Epithelial Tissue

  • Simple Epithelia
  • Stratified Epithelia
  • Glandular Epithelia
• Simple Epithelia


  • Simple squamous epithelium
  • Simple Cuboidal Epithelium
  • Simple columnar epithelium
  • Pseudostratified columnar epithelium
• Simple squamous epithelium


  • Bowman's capsule of kidney, endothelium, mesothelium
• Simple Cuboidal Epithelium


  • Non-ciliated - collecting tubules of kidney

  Ciliated - bronchioles, thyroid gland
• Simple columnar epithelium


  • Non-ciliated - pyloric end of stomach, gallbladder, small/large intestines

  Ciliated - fallopian tube, uterine tube, lungs