Why are leucocytes classified as granulocytes and agranulocytes? Name each cell and mention its functions.

Explanation

Depending on the presence and absence of granules, leucoytes are divided into two types Granulocytes and Agranulocytes.
Granulocytes: They are characterised by the presence of granules in cytoplasm. The granulocytes include neutrophils, eosinophils and basophils.
(i) Neutrophils: They constitute about 60-65% of total WBC.s. They are large and have many lobed nucleus. They are phagocytic in nature and appear in large number in and around the infected tissue.
(ii) Eosinophils: They have bilobed nucleus and constitute about 2-3% of total WBC.s. Eosinophil increase during certain types of parasitic infection and allergic reaction. It bring about detoxification of toxin.
(iii) Basophils: Basophil have lobed nucleus. They form 0.5 - 1.0% of the total leucocytes. They release chemicals during the process of inflammation.
Agranulocytes: They are characterised by the absence of granules in the cytoplasm. These are of two types Lymphocytes and Monocytes.
(i) Lymphocytes: These are about 20-25% of the total leucocytes. They produce antibodies during bacterial and viral infections.
(ii) Monocytes: They are the largest leucocytes and amoeboid in shape. These cells form 5-6% of the total leucocytes. They are phagocytic and can engulf bacteria.