Cellular events:
The cellular events in inflammation were first clarified by Russian biologist Elie Metchnikoff, in 1884. He inserted rose thorns into larvae of starfish and next day observed a grey zone around the thorns. The grey zone turned out to be an accumulation of large cells. As cells were large and possess phagocytic properties, he named them macrophages.
The most important function of inflammation is delivery of leukocytes, particularly neutrophils and monocytes, to the site of injury. Leukocytes engulf and kill bacteria and degrade necrotic tissue and immune complexes.
Sequence in journey of leukocytes from lumen of blood vessels into extravascular space is called extravasation. These events are divided into five processes:
- Margination
- Adhesion
- Emigration
- Phagocytosis
- Release of leukocyte products