... leucocytes. They are agranulocytes and have a large bean shaped nucleus. They only spend 2 to 3 days in the blood, and then they move to the tissues where they mature into phagocytic macrophages. Lymphocytes These make up approximately 30% of the circulating leucocytes. They are developed in the bone marrow, but continue to develop in the lymph nodes, the thymus gland, and the spleen. They are responsible for the specific immune response- the B-lymphocytes produce antibodies and the T-lymphocytes have a number of roles, including coordination of the immune response and direct cell destruction. Basophils These have an S shaped nucleus and granules that stain blue. They secrete large amounts of histamine that increases inflammation, and heparin that helps to keep the balance of blood clotting and not clotting. Eosinophils These have a double lobed nucleus and granules that stain red with the acid dye eosin. They help to control ...

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