Fig. 3.

TEM micrographs of lung tissue with CNT_Small (a–b) and CNT_Large (c–d). a Overview image of a large agglomeration of CNT_Small in the region where black arrowheads highlight very dense CNT agglomerates in the alveolar lumen. The CNTs are causing minor microtomy artefacts (stripes extending from the middle of the image towards the lower right corner). b A CNT_Small is seen interacting with a cell (insert), and a CNT observed freely inside the cytosol (white arrow). c Overview image showing CNT_Large between cells causing major microtomy artefacts. d TEM image of a dense agglomeration of CNT_Large resulting in holes and stripes in the ultrasection. A alveoli, AM Alveolar macrophage, E erythrocyte, N nucleus, P1 pneumocyte (type 1), and P2 pneumocyte (type 2). Black arrowheads indicate CNT agglomerates, whereas white arrowheads indicate single CNTs