Megakaryocyte (peripheral blood, human)

Electron microscopy. A small part of a megakaryocyte (see also inset) shows two nuclear segments (1) and two areas of cytoplasm. Seen at this magnification and close to the perinuclear area, the granular population can be divided into homogeneous electron-dense (2) and electron-grey (3) granules. The intermediate zone is subdivided by an interconnected channel system (4) (so-called demarcation membrane system, DMS). These demarcation channels traverse the marginal zone (5) and are in continuity with the irregular cell surface with small blunt microvilli.