Immunogold labeling of resting and activated platelets. Resting and activated platelets were incubated with Abs to PrP^C (308 or FL253), followed by protein G or secondary antibodies conjugated to 10 nm gold (arrowheads). In resting platelets preincubated with Ab 308 before embedding, PrP^C is seen around the periphery of the cell (A). In activated platelets PrP^C is found at the periphery of the cell and is associated with pseudopods (P, arrows) (B, whole mount; C, frozen section). In frozen sections of activated platelets labeled with Ab FL253, PrP^C was also localized to released exosomes (seen between cells, D; and at higher magnification, E).