Figure 4

Infectious skin lesions at day 3 after subcutaneous infection with S. aureus Xen36. A. Macroscopic aspect of day 3 lesions. More open lesions with skin rupture are observed in α₂AP KO/huPlg mice, compared to WT/null mice (P <0.01). B. Hematoxyllin-eosin staining of lesional skin from WT/null mouse showing a small abscess collection (arrows) without disruption of overlying skin (*). C. Hematoxyllin-eosin staining of lesional skin from α₂AP KO/huPlg mouse showing a large, less well-defined abscess collection (arrows), with extension (arrowheads) from the initial infection site both towards the overlying skin (*) (with resulting skin disruption and crust formation) and towards the underlying subdermal tissue and muscularis. D-E. Martius Scarlet Blue staining of the same lesion reveals a zone of fibrin deposition (F, red) at the periphery of the initial abscess site (arrows), but the infection has spread past this border of fibrin, through collagen fibers (blue), into underlying tissue layers (arrowheads).