Scanning electron micrographs of adherent Wistar (A, C, E, and F) and WF (B, D, and G) rat platelets from 1 to 2 minutes postadherence on poly-L-lysine–coated coverslips. Wistar platelets extend fine filopodia from round or spreading bodies (A, arrowheads) or exhibit spindle-shaped forms (C, arrowheads; higher magnification, E and F), unlike WF platelets, the majority of which are rounded, spreading with lamellipodial skirts, or fully spread. (A through D, original magnification ×2,800; E through G, original magnification ×7,100).