- A type of white blood cell filled with microscopic granules that are little sacs containing enzymes, compounds that digest microorganisms. Granulocytes are part of the innate immune system and have somewhat nonspecific, broad-based activity. They do not respond exclusively to specific antigens, as do B-cells and T-cells. Neutrophils, eosinophils and basophils are all types of granulocytes. They are named by the staining features of their granules in the laboratory: Neutrophils have "neutral" subtle granules; Eosinophils have prominent granules that stain readily with the acid dye eosin; and Basophils have prominent granules that stain readily basic (non acidic) dyes. This classification dates back to a time when certain structures could be identified in cells by histochemistry, but the functions of these intracellular structures were still not yet fathomed. However, the classification of granulocytes into neutrophils, eosinophils and basophils is still widely used (and quite useful).
* * *A mature granular leukocyte, including neutrophilic, acidophilic, and basophilic types of polymorphonuclear leukocytes, i.e., respectively, neutrophils, eosinophils, and basophils. [granulo- + G. kytos, cell]- immature g. an immature neutrophil; it may be neutrophilic, acidophilic, or basophilic in character.
* * *gran·u·lo·cyte 'gran-yə-lō-.sīt n a polymorphonuclear white blood cell (as a basophil, eosinophil, or neutrophil) with granule-containing cytoplasm compare AGRANULOCYTEgran·u·lo·cyt·ic .gran-yə-lō-'sit-ik adj
* * *n.any of a group of white blood cells that, when stained with Romanowsky stains, are seen to contain granules in their cytoplasm. They can be subclassified on the basis of the colour of the stained granules into neutrophil, eosinophil, and basophil.
* * *gran·u·lo·cyte (granґu-lo-sīt″) [granulo- + -cyte] 1. any cell containing granules. 2. granular leukocyte.
Medical dictionary. 2011.