Platelets from THC2 patients have a defect in α-granule content. Peripheral blood smears were stained with the P12 antibody against the α-granule protein TSP1 (red), and platelets were identified by labeling for F-actin (green). (A-B) One platelet from a control subject with normal content in α-granules. (C-D) One representative platelet of a THC2 patient with 2 TSP1⁺ granules. Scale bars represent 5 μm. Images were acquired as described in Figure 1 legend using a 100×/1.30 Plan Neofluar oil-immersion objective from Carl Zeiss.