Summary Neutrophils, eosinophils and basophils are the three types of blood cells refered to as granulocytes. The mature monocyte measures 12-15 um in diameter in blood smears and represents a circulating cell derived from bone marrow promonocytes. They are the largest cell in the blood. They contain a fairly large nucleus which is ovoid, kidney, or horseshoe-shaped often located in an eccentric position. Nucleoli sometimes seen.
Cell membrane has many finger-lide microvilli.
Life span 3 days. Functions Monocytes belong to the monocuclear-phagocyte system. These cells leave the blood and enter the tissue differentiating into macrophages. Interact with lymphocytes and play essential role with antigen interaction of immunocompetent cells. They contain a single, deeply-stained, spherical nucleus which can have an indentation.