Ultrastructural analysis of N.M.'s platelets.

All studies were performed on platelets fixed in PRP and incubated with rabbit antifibrinogen antibody (dilution 1:50) for 1 hour at RT. Bound antibodies were detected using a species-specific anti-IgG antibody (dilution 1:10) coupled to 10-nm gold particles overnight at 4°C before embedding. (A,D) Platelet sections are from a control donor. (B,C,E) Selected sections of platelets from patient N.M. (A) A nonstimulated control platelet is illustrated; few gold particles are present on the surface. (B) A platelet from N.M. shows a normal discoid shape and internal organization. Few gold particles are present at the platelet surface. (C) Another discoid platelet with larger vacuoles or a distended surface canalicular system is shown. The labeling for fibrinogen on the surface of this platelet was much more intense. (D) An example of TRAP6-activated control platelets (5 minutes). Even without continuous stirring, some aggregates have formed in the PRP, and labeling for fibrinogen is seen at the periphery of the aggregate. (E) TRAP6-activated platelets from the patient remained isolated or as small aggregates composed of 2 or 3 platelets; inside the platelet, large vacuoles are present and the granules have disappeared. Labeling at the platelet surface continues to be seen. Bars = 0.5 μm