The fine structure of freeze-fractured blood platelets.

The present study has examined the fine structure of freeze-fractured human platelets. Advances in methods used for cell preparation and freezing, together with better instrumentation, have resulted in improved preservation of platelet ultrastructure. Aspects of surface membrane topography and the number, depth of penetration, tortuosity and fenestration of channels belonging to the open canalicular system were revealed in a manner which cannot be fully appreciated in sections of platelets. Elements of the dense tubular system of channels and masses of glycogen were identified in the platelet replicas. The technic may provide an important approach for defining the structural physiology and pathology of blood platelets.