(also called polymorphonuclear neutrophil leukocyte, microphage), a type of white blood cell, or leukocyte, occurring in vertebrates and man. The diameter of a neutrophil ranges from 9 to 12 μ. The cytoplasm of these cells contains granules that attract both basic and acidic dyes, and this is why these leukocytes are called neutrophils.
A neutrophil is classified according to its degree of maturity: a metamyelocyte is a young neutrophil with an unsegmented nucleus, a rod neutrophil has a nucleus in the shape of a curved rod, and segmented, or filamented, neutrophils have segmented nuclei. Neutrophils are phagocytes that are capable of ingesting small foreign particles, including microbes. By elaborating hydrolytic enzymes, neutrophils can lyse dead tissue. Neutrophilia is an abnormal increase in the concentration of neutrophils in the blood. (SeeLEUKOCYTOSIS.)