1. Department of Theriogenology and Biotechnology, College of Veterinary Medicine, Seoul National University, Seoul 151-742, Republic of Korea.
2. Brain Korean 21 Program for Veterinary Science, College of Veterinary Medicine, Seoul National University, Seoul 151-742, Republic of Korea.
3. Department of Pathology, College of Veterinary Medicine, Seoul National University, Seoul 151-742, Republic of Korea.