Procoagulant balloon-shaped platelets. Ultrastructure of procoagulant platelets adhering to collagen-related peptide in the presence of calcium (2mM). Balloon platelets appear completely smooth, apart from an occasional membrane bleb. (Top panel) Comparison between normal platelets and balloon platelets (types 1 and 2). The cytoplasm of balloon platelets contain only few (if any) randomly distributed organelles, or remnants thereof. 2 such examples are presented in the bottom panels. (Left panel, type 1): Highly diluted cytoplasm and few inclusions. (Right panel, type 2): Moderately dense cytoplasm and higher levels of organelles. These images have been reproduced from Hess and Siljander³³ Figure 1C through E with permission from Springer Science+Business Media.