Study of the influence of multiwalled carbon nanotubes (12–14 nm) on the main target tissues of the bivalve Modiolus modiolus

The reaction of bivalves Modiolus modiolus to pulse (for 24 and 48 h) exposure with multiwalled carbon nanotubes (MWCNTs) (12–14 nm, MWNT concentration in sea water of 100 mg/L) is manifested in the ingestion of MWCNT aggregates formed in seawater despite their rapid sedimentation from the water column to the bottom of the aquariums. After 24 h, the MWCNT aggregates are observed in the intestinal lumen (size of 10 to 150 μm) and in the tubules of the digestive gland (10 to 50 μm). After 48 h, only large aggregates in contact with mucus and desquamated epithelium fragments are detected in the lumen of the intestine. The smallest aggregates seem to be inside epithelial cells. In the intestine, digestive gland, and gills, MWCNT aggregates induce histopathological changes in the epithelium (erosion, necrosis, trend towards increased vacuolization of the cells) and swelling of the connective tissue. In the gill epithelium after 48 h, patterns morphologically corresponding to apoptosis are observed. Despite significant organ damage, no change in the cellular composition of the hemolymph in mussels exposed to the MWCNTs is found.