1. Department of ENT, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
2. Department of Pathology, The First Affiliated Hospital of China Medical University, Shenyang, Liaoning 110001, P.R. China
3. Developmental Biology Teaching and Research Section, China Medical University, Shenyang, Liaoning 110001, P.R. China