[Histopathological studies of the acute and chronic toxic effects of 2 N-nitroso compounds on the blue mussel (Mytilus edulis)].

The acute and chronic effects of two N-Nitroso compounds (N-Nitrosodimethylamine) (DMN) and N-Methyl-N-Nitro-N-Nitrosoguanidine (MNNG) were studied by light microscopy after injection of the chemicals into the foot of the mussel, Mytilus edulis. Acute toxic effects: DMN produced dose-dependent (0.1 to 0.8 mg DMN/mussel) tissue alterations characterized by extensive inflammatory reactions in the Leydig cell tissue of the digestive gland, and necrosis in the germinal epithelium lining the genital ducts. MNNG produced dose-dependent (0.063 to 0.5 mg MNNG/mussel) tissue alterations characterized by extensive necrosis in the epithelial lining of the tubules of the digestive gland. Chronic toxic effects: 0.2 mg DMN/mussel given once a week for 8 weeks, and examined over a period of 30 weeks, revealed tissue alterations characterized by extensive collagenous scar tissue formation in between the tubules of the digestive gland, presence of numerous granulocytomas, and necrosis of the germinal epithelium of the genital ducts. 0.125 mg MNNG/mussel given once a week for 4 weeks, and examined over a period of 7 months, produced tissue alterations mainly characterized by encapsulation or replacement of damaged digestive tubules by collagenous scar tissue.