Severe λ-SPD, resulting in prolonged bleeding, in cappuccino mice.

(A) (B) Electron micrographs of air-dried, unstained normal (panel A) and mutant (panel B) platelets. The arrow illustrates one of the many dense bodies visible in the normal platelet and lacking in thecno/cno platelet shown. Most cno/cno platelets have no visible dense bodies, but a small number have 1 or 2. (C) Platelet aggregation (solid lines) was determined in whole blood by the impedance method in response to collagen (4 μg/mL). Note the reduction of cno/cno platelet aggregation. Thecno/cno platelet-aggregation response to low collagen (1 μg/mL) was likewise reduced (not shown). Release of ATP, determined simultaneously by luminescence (dashed lines), is undetectable incno/cno. Arrows indicate the time of collagen addition.