ils swallow up and destroy the bacteria.There are two kinds of lymphocytes, both of which form in the bone marrow. One kind leaves the marrow in search of the thymus organ, here they become T cells. The other type of lymphocytes, B cells, release antibodies into the blood when an infection is detected. The T cells release other substances that fight invaders in the bloodstream.Monocytes are produced mainly in the bone marrow. Like neutrophils, they carry out phagocytosis. Monocytes work with neutrophils to destroy bacteria. They play an especially important role in killing the bacteria that causes tuberculosis (425).Platelets are disk like structures that develop from cells found in the marrow. They help prevent the loss of blood from damaged vessels. If a small blood vessel is cut or broken, platelets stick to the damaged surface and to one another. As they pile up, they form a temporary seal over the injury. At the same time, the platelets release substances that start the process of blood clotting. Platelets are the smallest of the formed elements. They measure only about two to four microns in diameter. A micro liter of blood contains one hundred fifty thousand to four hundred thousand platelets (425)....
