Final answer:
Neutrophils are the small, granular leukocytes with a round, lobed nucleus and minimal cytoplasm, comprising the majority of leukocytes in the blood and playing a key role in the immune response.
Step-by-step explanation:
The small, granular leukocytes with a round nucleus and minimal cytoplasm are called neutrophils. Neutrophils are the most common leukocytes, making up 50-70% of the total leukocyte count, and are significant in fighting infections. Their granules are fine and usually appear light lilac after staining, and although they have minimal cytoplasm, they have multiple fine granules. The nucleus of a neutrophil is distinct and lobed, with two to five lobes that increase in number as the cell ages. As such, older neutrophils are often referred to as polymorphonuclear, or "polys," and younger ones as "bands." Neutrophils are one type of granular leukocytes, meaning they contain granules in their cytoplasm, alongside other kinds such as eosinophils and basophils. Granular leukocytes are short-lived cells produced in the red bone marrow and are vital components of the immune system.