Agranulocytes

They are leukocytes, with the absence of granules in their cytoplasm. Agranulocytes are further classified into monocytes and lymphocytes.

Monocytes

• These cells usually have a large bilobed nucleus, with a diameter of 12 to 20 micrometres.
• The nucleus is generally half-moon shaped or kidney-shaped and it occupies 6 to 8 per cent of WBCs.
• They are the garbage trucks of the immune system.
• The most important functions of monocytes are to migrate into tissues and clean up dead cells, protect against bloodborne pathogens and move very quickly to the sites of infections in the tissues.
• These white blood cells have a single bean-shaped nucleus, hence referred to as Monocytes.

Lymphocytes

• They play a vital role in producing antibodies.
• Their size ranges from 8 to 10 micrometres.
• They are commonly known as natural killer cells.
• They play an important role in body defence.
• These white blood cells are colourless cells formed in lymphoid tissue, hence referred to as lymphocytes.
• There are two main types of lymphocytes – B lymphocytes and T lymphocytes.
• These cells are very important in the immune systems and are responsible for humoral and cell-mediated immunity.

Platelets (Thrombocytes)

• Thrombocytes are specialized blood cells produced from bone marrow.
• Platelets come into play when there is bleeding or haemorrhage.
• They help in clotting and coagulation of blood. Platelets help in coagulation during a cut or wound.