Ag NW produced cellular exudate and irregular macrophages at Days 7 and 21. H & E-stained tissue sections recovered at 7 (left) and 21 days (right) post exposure to sham control (A-B), S-Ag NWs (C-D) or L-Ag NWs (E-F). All panels are Brightfield microscopy images of representative tissues from rats instilled with a single 1.0 ml/kg dose. Solid arrows indicate Ag NWs, and broken arrows indicate cellular exudate. Scale bar is 25 μm.