FIG. 1.

Subcutaneous TDM matrices in WT mice are primarily neutrophilic at early time points but later become pyogranulomatous to granulomatous, while Fib KO matrices become progressively suppurative. WT and Fib KO mice (n = 4 to 5 per time point) were injected subcutaneously in the scruff with 300 μl of TDM-coated 90-μm-diameter microspheres suspended within Matrigel. Matrices were removed for analysis at days 4 (A and E), 7 (B and F), and 12 (C, D, and G). Representative samples were fixed, sectioned, and stained with H&E. Photomicrographs represent leukocytic infiltrates in WT matrices (A to D) and in Fib KO matrices (E to G) typical for the depicted time point and are representative of three separate experiments. Multinucleated giant cells (black arrows) are present in panel C. An area showing neutrophil degeneration and necrosis, as well as peripheral eosinophilic ghost cells, as observed sporadically in 12-day-old TDM matrices from WT mice, is shown in panel D. The nuclear streaming of recruited neutrophils (red arrows) is prominent in panel F. Original magnification, ×1,000; bar = 50 μm.