Chapter 11 The Blood 331 Copyright Goodheart-Willcox Co., Inc. Monocytes Monocytes, the largest white blood cells, are produced in red bone marrow and then move to the blood, where they remain for one to three days before migrating into body tissues. Once they have arrived in the tissues, monocytes develop into macrophages that devour microorganisms. specific to a particular type of antigen. Natural killer cells are capable of killing cells infected with a virus and some tumor cells. Lymphocytes play an important role in the immune response. Lymphocytes are also essential in fighting cancer cells. Characteristics of White Blood Cells Granulocytes Type Microscopic appearance Percentage of WBCs Diameter Function neutrophil pale pink stain with fine granules in the cytoplasm multi-lobed, deep purple nucleus 55%–77% 10–12 micrometers “first responder” performs phagocytosis eosinophil rose-colored stain with coarse granules in the cytoplasm two blue-red, irregularly shaped nuclei 1%–3% 10–12 micrometers destroys parasitic worms controls allergic responses basophil dark blue stain with large purple granules in the cytoplasm nucleus with 2–3 lobes 1% 8–10 micrometers releases histamine produces heparin active in allergic reactions Agranulocytes Type Microscopic appearance Percentage of WBCs Diameter Function lymphocyte light blue-stained cytoplasm and dark blue, disc-shaped nucleus 25%–33% 7–8 micrometers forms antibodies to fight antigens fights cancer cells T cells and B cells monocyte grayish-blue cytoplasm blue-purple stained, kidney-shaped nucleus 2%–10% 7.5–10 micrometers morphs into macrophage that removes dead cell debris and attacks microorganisms Figure 11.8 © Body Scientifi c International Goodheart-Willcox Publisher