Final answer:
Monocytes are not the smallest white blood cells; they are large and characterized by indented nuclei. Monocytes transform into macrophages in tissues, where they perform essential immune functions such as phagocytosis and releasing chemicals that attract other immune cells.
Step-by-step explanation:
No, monocytes are not the smallest white blood cells; in fact, they are among the largest. Monocytes originate from myeloid stem cells and normally constitute about 2-8 percent of the total leukocyte count. They can be easily identified by their large size, ranging from 12-20 µm, and their distinctive indented or horseshoe-shaped nuclei.
Once monocytes leave the circulation and enter tissue, they differentiate into macrophages, which are crucial for phagocytizing debris, foreign pathogens, worn-out erythrocytes, and other dead or damaged cells. Macrophages also play an important role in the immune system by releasing antimicrobial defensins and chemotactic chemicals, which attract other leukocytes to the site of an infection.