Figure 10.

Autometallographic evaluation of tissue distribution of QD 1 and 14 days post-exposure. Silver enhancement staining of QD in lung tissue of rats 1 (A-C) and 14 (E-F) days after intratracheal instillation with 12.5 μg of QD-NH₂ or QD-COOH, or PBS (control). (A) Lung from a control rat 1 day post-exposure showing no silver staining. (B) Silver enhancement of QD-COOH in the lung of a rat 1 day post-exposure. QD can be seen distributed along alveolar epithelium and in AM. (C) QD-NH₂ enhanced with silver in rat lung 1 day after instillation. Distribution of QD-NH₂ does not appear to differ drastically from QD-COOH 1 day post-exposure in terms of deposition in the alveolar region and in macrophages; however, there does appear to be slightly more deposition in the airways as shown in panel C. QD can also be seen throughout the epithelium of a terminal bronchiole (TB). By day 14, QD-NH₂ (D) and QD-COOH (E) appear to be more concentrated in AM with a lesser amount in the tissue. QD-COOH can still be found in the interstitium and around vessels (green arrows). Both forms of QD were observed in bronchoalveolar lymphoid tissue (BALT). Silver enhancement of QD-COOH in BALT 14 days post-exposure is shown in panel F.