Neutrophilic granules in PMN (spleen, human)

Electron microscopy. A detail of the cytoplasm shows many granules of varying forms (round, elongated to dumb-bell), sizes and densities. The majority of these electron-grey to electron-lucent granules are the specific or secondary granules (diameter 0.2 up to length 0.8 μm). They contain substances like lysozyme, phagocytin to be secreted extracellularly involved in mobilization of inflammatory mediators and complement activation. Only with immuno-electron microscopy a third type of granule (secretion of gelatinases) and a fourth type of granule (so-called phosphasome) with alkaline phosphatase can be discerned.