Neutrophil granulocytes (also known as neutrophils) are the most abundant (40% to 75%) type of white blood cells in mammals and form an essential part of the innate immune system. They are formed from stem cells in the bone marrow. They are short-lived and highly motile. Neutrophils may be subdivided into segmented neutrophils (or segs) and banded neutrophils (or bands). They form part of the polymorphonuclear cell family (PMNs) together with basophils and eosinophils.