Microscopic distribution of misonidazole in mouse tissues.

Mice were injected with tritiated misonidazole (750 mg/kg-1), killed after 24h and the excised tissues prepared for autoradiography (ARG) to identify sites of accumulation. The previously reported high grain count associated with bound misonidazole metabolite(s) was observed in the liver. The ratio of grain count in the emulsion above the centrilobular hepatocytes to the count over connective tissue (stroma) was 12. A higher count ratio for 'target' cells to stroma was observed in the following cells/tissues: meibomian gland (ducts 110, acini 65), oesophagus (keratinised layer 60), incisor (enamel organ 17), nasal septum (subepithelial glands 13). For some of these tissues the explanation might appear to lie with localised hypoxia, but for others which were probably normoxic there is as yet no obvious reason for these findings.