Histologic appearance of lung metastases in Plg^−/− and control mice. Representative examples of lung sections of Plg^−/− mice (A, C, E, and G) and control mice (B, D, F, and H) 15 days after tumor cell inoculation stained with hematoxylin/eosin. (A and B) Clusters of small metastatic foci (asterisk) are numerous in the lungs of both Plg^−/− mice (A) and control mice (B). Small fibrin thrombi are numerous in Plg^−/− mice (arrows). Bar = 100 μm. (C and D) Higher magnification of these metastatic foci show cytologic features similar to the primary tumor in both Plg^−/− mice (C) and control mice (D). Metastatic foci are often associated with fibrin thrombi in Plg^−/− mice (asterisk) but rarely in control mice. Abnormal mitoses are indicated with arrows. Bar = 22 μm. (E and F ) Examples of large metastatic foci (asterisk) of Plg^−/− mice (E) and control mice (F ). Large metastatic foci in Plg^−/− mice tend to incorporate thrombi (arrows), whereas this is rare in control mice. (G and H) Higher magnification of large metastatic foci shows similar cytologic features in Plg^−/− mice (G) and control mice (H). Fibrin deposits are indicated with arrows. Bar = 22 μm.