They are immunologically characterized by Ig on their cell membrane. They have an eccentrically placed nucleus, contain abundant amounts of RER whose cisternae can be filled with antibody, and have a well-developed Golgi. The monocytes and lymphocytes are refered to a mononuclear white blood cells because their nuclei are not segmented. They do not contain prominent granules in their cytoplasm, in contrast to the granulocytes discussed earlier. Contain thicker central purple granulomere containing several kinds of granules.
Alpha granules are azurophilic. and contain fibrinogen, platelet-derived growth factor, etc.
They also store serotonin. Life span is 8-11 days.