A Gap-fill exercise
The least common type of leucocyte is called a . These cells contain cytoplasmic granules that contain , which is a mediator of inflammatory responses. Figure 1 is an image of a . These cells are increased in numbers following a viral infection. Erythrocytes are formed in the . During their maturation, an important organelle, the , is squeezed out of the cell. These cells have a characteristic shape. are formed by megakaryocytes in the bone marrow. are the largest of the white cells. These cells are the precursors of . Figure 2 shows an abnormal blood smear. It is abnormal because there are more than normal.