Fig. 3

Silver-enhancing and hematoxylin-eosin-stained Sprague–Dawley (SD) and Brown-Norway (BN) rat lung sections at 24 h post-treatment. Panels a & d: SD and BN air control shows an absence of signal; silver-stained positive cells are seen as black or black brown positivity (red arrows). In Panel b, SD at lung dose of 8 μg; in Panel c, at lung dose of 28 μg AgNPs and in Panel e, BN at lung dose 8 μg and Panel f, 26 μg AgNPs. Positive silver-stained cells are deposited in granuloma of BN lungs (arrow head pointing multi-nuclear giant cells). There are high levels of eosinophilic inflammation (black arrows) in BN lungs (internal scale bar = 20 μm for all)