noun, plural: neutrophils
A type of polymorphonuclear leukocyte characterized by having multilobed nucleus, presence of cytoplasmic granules that render the cell neutral or faintly pink when stained with usual dyes (e.g. H&E stain), and whose immune function is primarily phagocytosis
The polymorphonuclear leukocytes are characterized by having nuclei with three or more lobes joined by filamentous connections and cytoplasmic granules perceptible through conventional staining and light microscopy. In humans, the polymorphonuclear leucocytes may be subdivided into eosinophils, basophils and neutrophils according to the staining properties of the granules using a Romanovsky type stain. The neutrophils, in particular, are so named because it stains a neutral pink.
Similar to other polymorphonuclear leukocytes, the neutrophil goes through the granulocytic series of hematopoiesis. Its developmental stages are as follows: hemocytoblast → common myeloid progenitor (or CFU-GEMM) → CFU-GM → CFU-G → myeloblast → neutrophilic promyelocyte → neutrophilic myelocyte → neutrophilic metamyelocyte → neutrophilic band cell → neutrophil. Most neutrophils are found in the blood stream. However, they can migrate to certain tissues as they are typically the first responders of chemoattractants that signal when the tissue is infected, damaged, or inflamed. They are one of the phagocytes, capable of phagocytosis.
The neutrophils are relatively short-lived (with a lifetime ranging from 6 hours to few days), highly motile, with multilobed nucleus, and size ranging from 10 to 12 μm. In humans, they are the most abundant type of white blood cells, about 40% to 70%. They are usually the first line of defense against pathogens. Their main targets are bacteria and fungi.