| Description |
Electron microscopy. These anucleate cells (2-4 μm) are derived from cytoplasmic fragments of a megakaryocyte and when free floating in the peripheral blood they develop thin extensions. These platelets contain among others few mitochondria (1), microtubules (2), glycogen (3), small vacuoles (4, open canalicular system), elements of dense smooth tubular system (7). The arrow indicates the open connection of the OCS with the environment. (x) indicates a cross-section of the outer blood compartment. Homogeneous electron-dense delta granules (5) contain plasma-absorbed serotonin, calcium ions, ADP and ATP etc. The electron-grey granules 6) with a dark centre (alpha-granula) are variable in size and contain among others platelet-derived growth factor, factor VIII (von Willebrand), thrombospondin, fibronectin, fibrinogen. |
