Final answer:
Neutrophils, eosinophils, and basophils are grouped as granulocytes, which are recognized by their distinctively colored granules on a stained blood smear.
Step-by-step explanation:
Neutrophils, eosinophils, and basophils are called granulocytes because they have prominent cytoplasmic inclusions that appear with identifying, characteristic colors when stained on a blood smear. These cells are categorized based on their appearance after histological staining and contain abundant granules within their cytoplasm. For example, a neutrophil's granules stain light lilac, an eosinophil's granules stain reddish-orange, and a basophil's granules stain dark blue to purple. Contrasting granulocytes are the agranulocytes which include lymphocytes and monocytes; these cells do not contain visible granules in the cytoplasm after staining.