Osmotic correction to elastic area compressibility measurements on red cell membrane.

Human-platelet dense bodies (secretory granules) have been visualized by electron microscopy in cells maintained in a hydrated state, and their sequential release after stimulation by thrombin has been observed in situ. The pattern of dense body release from individual platelets suggests that a a portion of the dense body complement of a single cell can be extruded without appreciable change in the position of the remaining dense bodies.