White cells can be classified as belonging to 2 main groups - agranulocytes and the granulocytes. Several types from these two groups are described below. Neutrophils move to infected parts of the body to engulf and consume invading bacteria. Eosinophils are thought to have anti-histamine properties and their population in the bloodstream is governed by hormones produced by the adrenal cortex. They also are able to ingest bacteria but normally do so at a lesser extent than neutrophils.
Basophils contain heparin, histamine and serotinin.
Where they have not been discharged from the cell, small granules are usually visible around the nucleus. Monocytes Fig.1c often behave in a similar way to neutrophils by travelling to inflamed areas of the body to ingest bacteria and larger foreign particles. Lymphocytes are of special significance as they are involved with the body's immune defence mechanism and either help mediate or initiate antibody production. Both types of agranulocytes have non-granular cytoplasm. Fig.2 shows a tiny section from a human rib.