Purulent Inflammation

• In purulent inflammation, pus is the predominant feature.
  • Pus is an admixture of dead and dying neutrophils with necrotic cells and a pyogenic agent.
    • Proteolytic enzymes released by the dying neutrophils lyse tissue cells to produce a fluid.
• Colour varies depending upon the agent.
  • May be white, yellow, green or brown.
• An abscess is a circumscribed sphere of pus surrounded by a pyogenic membrane.
  • The pyogenic membrane is composed of capillaries bringing neutrophils into the sphere.
  • This rapidly becomes enveloped by a fibrous tissue capsule.
    • A local connective tissue response attempting to wall off the purulent irritant from nearby normal tissue.