Confocal images of the pleura at 45 days. Bright green structures are connective tissue cables highlighted using maximum intensity projection from original image data. Particles and fibers are shown in orange. When protein coated they appear yellow. These images are from projected three dimensional reconstructions. The scale bars are in μm and are shown in each image in the surrounding frames.  Air control Pleura at 45 days .

Confocal microscopy: Compartmental fiber distribution in the parenchyma for groups 1 Air control, 2 Chrysotile & brake dust, 3 Brake dust and 4 Crocidolite asbestos as a function of time through 91 days.

Confocal microscopy Interstitial Fibrosis Assay — 91 days: Group 1 Air control shows a typical profile of ciliated airway epithelium. Group 2 Chrysotile & brake dust: A few macrophages are observed on the ciliated distal airway. A few chrysotile or brake dust particles can be observed within the macrophages. Group 3 Brake dust: A macrophage is observed on the ciliated distal airway. Chrysotile or brake dust particles can be observed within the macrophage. Group 4 Crocidolite asbestos: Intense inflammatory response interlaced with collagen (white) to the crocidolite fibers in the region adjacent to the airway and alveolar duct.

Confocal microscopy image from the croci- dolite exposed animals showing pleural adhesion at experimental day 28 (end of the 28 day exposure period). Fibers are indicated in red. See text for fur- ther details. Scale is shown in lower left of each panel.

Confocal images of the pleura at 45 days. Bright green structures are connective tissue cables highlighted using maximum intensity projection from original image data. Particles and fibers are shown in orange. When protein coated they appear yellow. These images are from projected three dimensional reconstructions. The scale bars are in μm and are shown in each image in the surrounding frames.  Air control Pleura at 45 days .

Exposure aerosol – mean ± SE of the number of the total number of fibers (all lengths with 3:1 aspect ratio) and particles in each group. The numbers shown above the bars are the mean values.

Scanning electron micrographs of the diaphragm at 0 days following cessation of exposure. Crocidolite asbestos exposure group. Plate 1 shows neutrophils of the surface of the diaphragm. Plate 2 shows a 5.3 μm crocidolite fiber supported by the mesothelial microvilli adjacent to a stomata.

Back-scattered-electon imaging mode of an SEM field of talc, showing particles widely varied in size and shape, generally 2–70 mm. (size bar at 100 n). Spectral boxes show particles representatively chosen for analysis by EDS under spot quantitative acquisition mode. (450x).

EDS spectrum of two talc particles. Peaks for Mg and Si are present, along with a peak for O at approximately 5 keV. The Mg/Si atomic weight % ratio for both particles is 0.644 typical for talc and is within 1% of the theoretical value of 0.649. (a) top spectrum: no background Al (aluminum) peak was detectable in this particle. (b) bottom spectrum: a small Al peak (atomic weight % <2) was seen here, as it was in about half the JBP particles we analyzed. These small Al peaks, when present, were thought to come from the EDS background environment, specifically the underlying metallic stub.

Confocal images of the lung at 180 days. Bright green structures are connective tissue cables highlighted using maximum intensity projection from original image data. Particles and fibers are shown in orange. When protein coated they appear yellow. These images are from projected three dimensional reconstructions. The scale bars are in μm and are shown in each image in the surrounding frames.

Panel 1: Group 4, Brake dust high dose at 180 days: Normal parenchyma showing alveoli. A short fiber is present as well a macrophage with a particle/short fiber.
Panel 2: Group 5, TiO2 particle control at 180 days: Normal Parenchyma with an alveolar duct. Present are macrophages some with TiO2 particles.
Panel 3: Group 7, chrysotile high dose at 180 days: Normal Parenchyma with an alveolar duct. A few short chrysotile fibers are present with macrophages.
Panel 4: Group 8, crocidolite asbestos at 180 days: Upper portion is a conducting airway with airway epithelium. Below is a matrix of activated Interstitial connective tissue with long & shorter crocidolite fibers.
Panel 5: Group 9, amosite asbestos at 180 days: On the left is a distal airway with amosite fibers penetrating and traversing the airway wall (center). Interstitial connective tissue with localized collagen response is present. On the right is a granuloma with numerous amosite fibers.
Panel 6: Group 9, amosite asbestos at 180 days: Distal airway with adjacent localized interstitial connective tissue response. In the center is a granuloma with long and shorter amosite fibers. Below left is an extensive collagen matrix with long and shorter amosite fibers

Confocal images of the pleura at 45 days. Bright green structures are connective tissue cables highlighted using maximum intensity projection from original image data. Particles and fibers are shown in orange. When protein coated they appear yellow. These images are from projected three dimensional reconstructions. The scale bars are in μm and are shown in each image in the surrounding frames.

Panel 1: Group 1, Air control Pleura at 45 days
Panel 2: Group 4 High dose brake dust Pleura at 45 days
Panel 3: Group 5 TiO2 particle control Pleura at 45 days
Panel 4: Group 7 Chrysotile high dose Pleura at 45 days
Panel 5: Group 8 Crocidolite asbestos Pleura at 45 days
Panel 6: Group 9 Amosite asbestos Pleura at 45 days

View of the pleural space from an animal exposed to amosite asbestos at 272 days postexposure. The subpleural alveolar septa seen in the left center of the image contains fibrotic lesions (thicker bright white matrix is indicative of enhanced collagen deposition). The parietal pleura and chest wall is shown on the right. Within the alveolus on the left, a number of subpleural macrophages can be seen.

The parietal pleural surface from an animal exposed to amosite asbestos at 90 days postexposure. Numerous macrophages are observed on the parietal pleural (the triangular indentation seen in the micrograph was likely due to the back of a forceps, which was used for straightening the diaphragm after removal from the animal).

Confocal micrographs of the lung at 2 wk after cessation of exposure. (A), (B), (C) show an original single-scan image of the region. (D), (E), (F) show the reconstructed three-dimensional images of the same regions, which are composed of 70 serial sections. The length bars are 10 μm.

Confocal micrographs recorded from the 1-mo postexposure group. All images were digitally processed from original optical sections, approximately 0.5 μm thick, recorded from undisturbed regions of the lung. Pulmonary tissue appears as a gray-scale composite with profiles of test article (red). At this time point, very few micrographs actually contain profiles of the test article. These particular images were selected to show the appearance of chrysotile, when present. Fibers were found on the surface of ciliated airways. (A) Cross section of a large ciliated airway near a bifurcation with a short, thin fibril inside a cell adjacent to the epithelium. Scale bar is 10 μm. Fibers were observed in the alveoli. (B) Typical field of view in the parenchymal region showing an alveolar wall, and alveolar space. Scale bar is 10 μm. Occasional fibers were observed phagocytosed by alveolar macrophages. (C) Fiber clearance by an alveolar macrophage. Scale bar is 10 μm. Very few fibrils were observed in alveolar interstitial spaces, including distal pulmonary lymphatics. (D) Distal pulmonary lymphatic duct (lower center of the image) devoid of any chrysotile fibrils. Calcified structures were occasionally found on the alveolar epithelium, but no adverse tissue response has been observed associated with these structures. Scale bar is 10 μm.

Confocal micrographs of parenchymal region from representative fields of view recorded from three treatment groups at the 90-day exposure, 92-day recovery time point: high dose (A), medium dose (B), and air control (C). Fine particulate material (red) can be seen inside foamy alveolar macrophages (arrow, A). Occasionally, neutrophils with partially engulfed fibers were observed in alveolar spaces (arrow, B). Alveolar macrophages were occasionally present in the parenchymal region of air control animals (C). Typical parenchymal region fields-of-view (D through F) show alveolar septa and, very rarely, a fiber in contact with the alveolar epithelial surface (E). Bar represents 10 μm.

SEM micrograph of an activated macrophage surrounded by fibrin and red blood cells.

SEM micrograph of macrophages activated on tissue surface. 2000 times magnification.

SEM micrograph of a normal lung showing, alveolar surfaces 8n lung makig up part of the pulmonary acinus.