Which of the following leukocytes is the most abundant in circulating blood?

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Neutrophils are the most common leukocyte. Neutrophils typically make up 40-70% of all the white blood cells in circulation. Each neutrophil has a lobed nucleus and faint granules containing lysozymes used to destroy bacteria. The number of neutrophils in circulation rises in response to bacterial infections. Basophils are the least common leukocyte. Basophils average from 0% to less than 1% of all the white blood cells in circulation. The large, dark blue-purple granules of a basophil are so prominent that it is difficult to see the S- or U-shaped nucleus. The number of basophils in circulation tends to increase with allergies. A basophil's primary function is to release two chemicals-histamine and heparin-for defense. Eosinophils make up 0-6% of the total circulating white blood cells. Their granules stain orange to bright red, making them 1 Easy to distinguish from other WBCs. Eosinophil numbers increase with parasitic infections and allergies. The chemicals secreted by them can be effective against large parasites such as hookworms and tapeworms. Monocytes are the largest of the WBCs, measuring 2-3 times the size of a red blood cell. They have a large, horseshoe-shaped nucleus surrounded by abundant cytoplasm. Monocytes migrate to tissues to become macrophages where they function to phagocytize (eat) dead and dying tissue, microorganisms, and any other foreign matter or debris. The number of monocytes in circulation increases with inflammation and viral infections. Lymphocytes are fairly common in circulating blood, making up 20%-50% of the total WBCs.

Which of the Following Leukocytes Is the Most Abundant in Circulating