Unlike normal platelets, platelets treated with antibody 7E3 do not form multiple layers on a collagen-coated surface.

Human platelets were prepared and added to collagen-coated microtiter wells as in Figure 3. The specimens were then prepared for transmission electron microscopy after spreading for 1 hour at 22°C. (A) Three images from different regions (Ai, Aii, and Aiii) containing untreated human platelets showing an initial layer of spread platelets (lower thick arrow) and multiple additional layers of platelets with variably intact granulomeres and closely apposed membranes. The thin upper arrow points to a platelet that is tethered to the spread platelets below but retains an intact granulomere. (B) Three images from different regions containing 7E3-treated platelets (Bi, Bii, and Biii), which demonstrate primarily a single layer of platelets. Where one platelet partially spreads over another, the borders of the platelets remain distinct. Granulomeres of the 7E3-treated platelets making up the initial layer (Bi, Biii, arrowheads) are more distinct than those making up the initial layer of the untreated platelets shown in panel A.