1. Laboratory of Pathology, Toxicology Division Institute of Environmental Toxicology, Uchimoriya-machi 4321, Mitsukaido-shi, Ibaraki 303-0043, Japan,
2. Laboratory of Pathology, Toxicology Division Institute of Environmental Toxicology, Uchimoriya-machi 4321, Mitsukaido-shi, Ibaraki 303-0043, Japan
3. Division of Study Planning and Consultation, Institute of Environmental Toxicology, Uchimoriya-machi 4321, Mitsukaido-shi, Ibaraki 303-0043, Japan