Final answer:
Margination is the process where neutrophils adhere to the blood vessel walls in response to infection or inflammation. This precedes diapedesis, where they emigrate from the vessel to the site of infection, following chemical signals in a process called positive chemotaxis to perform phagocytosis.
Step-by-step explanation:
Margination refers to the process whereby neutrophils and other white blood cells (leukocytes) adhere to the inner walls of the blood vessels, particularly in the area of inflammation or infection. This process is distinct from the later steps where leukocytes move out of the blood vessel, a process known as diapedesis or emigration. Upon receiving chemical signals released by injured or infected cells, a phenomenon called positive chemotaxis, neutrophils respond by squeezing through the vessel wall into the tissue spaces to reach the site of infection and carry out their immune response functions, which includes phagocytosis, engulfing and destroying pathogens.