granulocyte
Meaning of granulocyte: Granulocytes are white blood cells containing microscopic granules of enzymes, including neutrophils, eosinophils, and basophils, each specialized for a different immune role.
Definition of granulocyte
A granulocyte is a type of white blood cell whose cytoplasm contains visible granules under the microscope, small sacs holding enzymes and other substances released when the cell is activated. Granulocytes make up the majority of circulating white blood cells and form a key part of the body's immediate immune defenses.
Three distinct types of granulocyte are recognized, neutrophils, eosinophils, and basophils, each identified by how their granules take up laboratory stains and each specialized for a somewhat different role. Neutrophils are the most abundant and respond quickly to bacterial infection, eosinophils are involved in responses to parasites and allergic conditions, and basophils release chemicals involved in allergic reactions.
Granulocytes are also known as polymorphonuclear leukocytes, a name referring to the irregularly lobed shape of their nucleus, and changes in the number of circulating granulocytes, whether increased or decreased, are a common and useful finding on routine blood testing.
Also known as
Used in a sentence
The complete blood count showed a reduced granulocyte count.
Good to know
Neutrophils make up the large majority of circulating granulocytes, so a change in total granulocyte count on a blood test most often reflects a change in neutrophil number specifically.
Word origin
Where “granulocyte” comes from
Formed from Latin granulum, meaning a little grain, and Greek kytos, meaning cell.