Fig. 3.

Light (H&E) and electron microscopy (TEM) micrographs (a, d, g, l, o and b–c, e–f, h–i, m–n, p–q, respectively), showing lung tissue of control (a–c), AgNO₃- (d–i) and AgNPs-treated (l–q) rats, 28 days after i.t. instillation. Normal alveolar and bronchiolar morphology is visibly conserved in controls (a–c), while morphological and ultrastructural alterations are manifest in the lungs of treated animals, after both AgNO₃ and AgNPs. Collapsed alveoli, associated with architectural distorted bronchioli, both exhibiting wall thickening (d, g, l and o); markedly damaged alveolar area showing apoptotic and necrotic cell death (e); altered, thickened alveolar wall, characterized by the presence of type II pneumocytes (PII) filled by vacuolized multi-vesicular bodies (f), with detail of activated monocyte (insert in f); early apoptosis (h); injured alveolar wall displaying limited presence of collagen fibres (i); haemorrhagic blood clots close to collagen engulfed areas (m and q); activated macrophage and apoptosis (n); type II pneumocytes (PII) filled by vacuolized multi-vesicular bodies together with extensive deposition of encapsulated collagen fibril bundles (p). Light microscopy magnification: 40x (a, d, g, l and o). Electron Microscopy original magnification: x 5,000 (b–c, e–f, h–i, m–n, q); x 7,500 (p).