E2-treated mice are protected from collagen/epinephrine-induced thromboembolism. (A) Thromboembolism was induced by injection of a collagen (0.4 mg/kg) and epinephrine (60 μg/kg) mixture into the jugular vein. All non-E2–treated mice (12 of 12) and 11 of 12 sham-operated mice died within 5 minutes, whereas all E2-treated mice (10 of 10) survived. (B) Representative sections of hematoxylin-eosin–stained lungs from a control mouse that died during the assay and an E2-treated mouse that survived and was killed 10 minutes after injection of collagen/epinephrine mixture. Original magnification ×400. (C) Platelet staining (αIIb in brown) of lung sections from mice treated or not with E2. Original magnification, ×100.