1. Division of Aerospace Medicine, Department of Cell PhysiologyThe Jikei University School of Medicine, Nishishinbashi 3‐25‐8 Minatoku Tokyo Japan
2. Department of Life and Food SciencesObihiro University of Agriculture and Veterinary Medicine Obihiro Japan
3. Laboratory of Veterinary AnatomyObihiro University of Agriculture and Veterinary Medicine Obihiro Japan
4. The United Graduate School of Agricultural SciencesIwate University Morioka Japan
5. Department of MedicineAsahikawa Medical University Asahikawa Japan
6. Laboratory of TheriogenologyObihiro University of Agriculture and Veterinary Medicine Obihiro Japan