Neutrophils

A Neutrophil is a type of leukocyte (white blood cell) whose cytoplasm is filled with staining granules. Neutrophils play an important role in the immune system as they constitute the first line defense against bacterial and fungal infection. A neutrophil is essential for phagocytosis and proteolysis. The name "neutrophil" comes from the fact that it does not get stained strongly by either acid or basic dyes but get stained readily by neutral dyes.

Neutrophils have an average diameter of 12-15 micrometers (µm). The average half-life of neutrophils in the circulation is 12 hours when they are not activated. But when they are activated, they live between 1 and 2 days. When a bacterium or a virus first enters the organism, it first encounters a neutrophil. When bacteria enter the body, neutrophils migrate to the site of infection or inflammation through the blood vessels, then through intertial tissue. Neutrophils are produced in the bone marrow and are fully mature when they are released into the blood stream.