FIG 3.

D39 invades the myocardium. High-magnification H&E-stained images (left) and IFM images (right) of a representative discrete cardiac microlesion (A) and immune cell-infiltrated foci (B) in cardiac sections from 10- to 12-week-old mice infected with D39 obtained at 24 hpi. Black arrows, areas of hydropic degeneration; white arrows, infiltrated immune cells. IFM was performed using antiserum against serotype 2 capsular polysaccharide. Images are of the same cardiac microlesion, and serial sections from paraffin-embedded tissue were stained. Magnifications, ×400 (H&E-stained sections) and ×40 with a zoom factor of 1.5 (IFM images). (C) Low-magnification image of an IFM-stained section from a D39-infected mouse showing multiple positive S. pneumoniae signals. (Inset) Higher-magnification view of the boxed section. Magnifications, ×40 with a zoom factor of 0.6 and ×40 with a zoom factor of 4.0 (inset).