Absence of spindle-shaped forms among adhered WF rat platelets. Immunofluorescence staining of Wistar (a, c, and e) and WF (b, d, and f) rat platelets with rhodamine-phalloidin after 30 seconds (a and b), 1 minute (c and d), or 30 minutes (e and f) of adherence to poly-L-lysine coated glass coverslips. Spindle-shaped Wistar platelet forms are indicated by arrows (a and c); these forms are absent in WF rat platelet preparations (b and d), which contain rounded or spreading forms. By 30 minutes, the majority of Wistar and WF rat platelets are fully spread. Original magnification ×630.