Differences in the kinetics of the morphological changes of Wistar and WF rat platelets on adhesion to Formvar-coated, carbon-stabilized grids as described in Materials and Methods. Platelets were allowed to adhere for 30 seconds, 1 minute, 2 minutes, 5 minutes, 10 minutes, 15 minutes, or 30 minutes. One hundred platelets were counted for each rat at each time point and assigned to the following shape categories: round, round or spreading with stubby filopodia, spindle shaped, round or spreading with long filopodia, spreading with lamellipodia, and fully spread. One hundred platelets were evaluated for each of the five rats of each strain at each of the seven time points, except for the 2-minute time point for Wistar rat platelets, in which data was collected from 100 platelets from four rats, rather than five rats. Hence, the experimental data for this adhesion analysis represent a total of 3,500 WF rat platelets, and 3,400 Wistar rat platelets for five experiments conducted at each of the seven time points. Each point represents the mean ± 1 SEM for five rats of each strain. (○) and (---), Wistar rats; (•) and (—), WF rats.