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Quick Facts

A basophil is a granular leukocyte with an irregularly shaped, pale-staining nucleus that is partially constricted into two lobes, and with cytoplasm that contains coarse, bluish-black granules of variable size. Basophils contain vasoactive amines such as histamine and serotonin, which are released on appropriate stimulation (Dorland, 2011).

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Cell Morphology

Basophils are the rarest type of leukocytes, accounting for only 0.5% of all leukocytes. The concentration of basophils is around 20–50 per microliter of blood.

The diameter of a basophil is 10–14 μm, making them larger the erythrocytes. Their nuclei have two lobes that are either U- or S-shaped. The cytoplasm of basophils contains large granules that contain histamine and various molecules which mediate inflammation during an allergic response (Marieb, Wilhelm and Mallatt, 2012).

Basophils have Fc receptors on their cell surface which are antibody receptors that bind to Immunoglobin E (IgE) causing an allergic reaction. Basophils also possess the CD40L protein on their cell surface. CD40L interacts with the CD40 protein that is found on the cell surface of lymphocytes. This interaction results in an additional production of type IgE, therefore, mediating an immune response against parasites (Pawlina, 2016). Basophils have a short lifespan of around 8 hours in the blood (Pawlina, 2016).


In the red bone marrow, a hematopoietic stem cell differentiates into a myeloid stem cell which gives rise to basophils. Development usually takes 3–7 days and mature cells are stored in marrow before release into the bloodstream (Pawlina, 2016).


Basophils are mediators of allergic and inflammatory responses. Histamine released by basophils is a vasodilator meaning that is increases blood flow and decreases blood pressure. Heparin released by basophils is an anticoagulant which prevents blood from clotting too quickly (Silverthorn et al., 2013). Additionally, like all granulocytes, basophils are phagocytic (Marieb, Wilhelm and Mallatt, 2012).

List of Clinical Correlates




Dorland, W. (2011) Dorland's Illustrated Medical Dictionary. 32nd edn. Philadelphia, USA: Elsevier Saunders.

Marieb, E. N., Wilhelm, P. B. and Mallatt, J. (2012) Human Anatomy. 14th edn.: Benjamin Cummings.

Pawlina, W. 2016. Histology: A text and atlas with correlated cell and molecular biology. 7th ed. Philadelphia: Wolters Kluwer.

Silverthorn, D. U., Johnson, B. R., Ober, W. C., Garrison, C. W. and Silverthorn, A. C. (2013) Human Physiology: An Integrated Approach. Pearson Education.

Complete Anatomy

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Complete Anatomy