Representative scanning electron micrographs of resting platelets and platelets activated with HIT serum in the presence of heparin.

Resting platelets or platelets incubated with HIT serum in the presence of 0.1 U/mL heparin were fixed with 2% glutaraldehyde and processed for SEM. (A) The morphology of a representative normal resting platelet. Resting platelets were observed to generally maintain a discoid form. (B) The morphology of a representative platelet incubated with HIT serum. These platelets demonstrated several morphological changes including absence of a discoid form,1 presence of pseudopodia,2 and presence of microparticles near the ends of pseudopodia3 (indicated by arrows). (C) Microparticles that are clearly distinct and separate from the platelet body localize near the terminal end of a pseudopod (indicated by arrow).