Monocyte (peripheral blood, human)

Electron microscopy. In this picture the large nucleus of this cell (diameter of 12-20 μm) is twice sectioned (1). Golgi areas (2), a few profiles of rough endoplasmic reticulum (3) and many free ribosomes are present. There are many mitochondria (4) as well as small-sized light vesicles (5). The cytoplasm contains scattered homogeneous electron-dense lysosomal granules (primary or azurophilic granules (6) with acid phosphatase, arylsulfatase) in variable amounts and sizes. Thin filopodia (7) reflect the ameboid movement (note several small subplasmalemmal clefts) and phagocytic ability.