Effect of NO on the thrombin-induced changes in platelet morphology. Scanning electron micrographs prepared from aliquots withdrawn as depicted by letters i-vii in Figure 1 and Figure 3. (A) Control (stirred 1 minute); (B) thrombin (2 minutes); (C) thrombin (10 minutes); (D) NO (1 minute) followed by NO and thrombin together (2 minutes); (E) NO (1 minute) plus NO and thrombin together (2 minutes), then stop of NO infusion (2 minutes); (F) NO (1 minute) plus NO and thrombin together (2 minutes), then stop of NO infusion (7 minutes); (G) NO (1 minute) plus NO and thrombin together (2 minutes), then stop of NO (2 minutes); then NO reinfusion (5 minutes). Micrographs are from a single experiment, representative of 4. The micrographs were photographed on the electron microscope screen with a Leica M2 camera, exposure time ⅛ seconds, aperture 4, and a focal distance of 50 mm; screen magnification was 7000 ×.