1. Animal Genetic Resources Station, National Institute of Animal Science, RDA, Namwon 590-832, Korea.
2. Department of Physiology, Institute of Health Sciences, Gyeongsang National University School of Medicine, Jinju 660-751, Korea.
3. Department of Obstetrics and Gynecology, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon 630-723, Korea.