1. Department of Veterinary Anatomy, Faculty of Agriculture, University of Miyazaki, Miyazaki 889-2192, Japan.
2. Department of Veterinary Anatomy and Cell Biology, College of Veterinary Medicine, Seoul National University, Seoul 151-742, Korea.
3. AgResearch, The Hopkirk Research Institute, Grasslands Research Centre, Palmerston North 4442, New Zealand.