Figure 9From: Asbestos, carbon nanotubes and the pleural mesothelium: a review of the hypothesis regarding the role of long fibre retention in the parietal pleura, inflammation and mesotheliomaA) diagram showing the events leading up to formation of black spots. A1) particles enter the pleural space; A2) in focusing to exit via the stoma (St) some particles interstitialise through the loose lymphatic capillary endothelium and macrophages begin to accumulate in response; A3) macrophages and particles form a mature 'black spot' with mesenchymal cell activation and proliferation depending on the toxicity and dose of the particle. B) In B1 a single long fibre is intercepted as it attempts to negotiate the stomatal opening and is retained; 2) other fibres are caught up and there is an accumulation of retained long fibres; 3) macrophages attempt to phagocytose the fibres and undergo frustrated phagocytosis releasing a range of pro-inflammatory, genotoxic and mitogenic mediators close to the pleural mesothelial cells. PM = pleural mesothelium; St = stoma; LC = lymph capillary.Back to article page