Monocyte from a blood film, normally constituting 2-4% of total WBCs. It shows abundant cytoplasm, a pale, horseshoe-shaped nucleus, and is phagocytic. Cells with this morphology and function found elsewhere in the body are called "macrophages" or "histiocytes". Markers include Fc receptors and complement (C3b) receptors, both of which contribute to opsonization.
Two platelets can be seen among the RBCs a little to the left.