Platelets of double mutant mice have normal ultrastructure, other than a lack of dense granules.

Platelets of normal C57BL/6J (A), pale ear (ep/ep) (B), pearl (pe/pe) (C), and double mutant (ep/ep, pe/pe) (D) mice were analyzed by electron microscopy. Dense granules (arrows) are common in normal platelets, less so in pale ear and are not apparent in pearl or double mutant cells. The α granules (arrowheads) are equally common in both qualitative and quantitative senses in all platelet genetic types. Bars represent 1 μm.