mature white blood cells with granules in the cytoplasm

Granulocytes are a category of white blood cells which have granules in their cytoplasm.[1] They are also called polymorphonuclear leukocytes because of the shape of the nucleus, which has three segments. The term polymorphonuclear leukocyte often refers just to neutrophils, the most abundant of the granulocytes.

A neutrophil with a segmented nucleus (center and surrounded by erythrocytes), the intra-cellular granules are visible in the cytoplasm (Giemsa stained high magnification)
Eosinophil granulocyte
A basophil with lobed nuclei surrounded by erythrocytes

Granulocytes are released from the bone marrow. They operate by phagocytosis and other means.[2]

Types of granulocytes


There are three types of granulocytes, distinguished by their appearance under Wright's stain:

Their names are derived from their staining characteristics; for example, the most abundant granulocyte is the neutrophil granulocyte, which has neutrally-staining cytoplasmic granules.

Other white blood cells which are not granulocytes are mainly lymphocytes and monocytes.



  1. Hoffbrand A.V. Pettit J.E. and Moss P.A.H. 2005. Essential haematology 4th ed, Blackwell, Oxford. ISBN 0-632-05153-1
  2. Ernst J.D. and Stendahl O. (eds) 2006. Phagocytosis of bacteria and bacterial pathogenicity, Cambridge University Press. ISBN 0-521-84569-6 Website