1. Center for Perinatal and Neonatal Care, Tohoku University Hospital, Sendai, Miyagi, Japan
2. Department of Anatomy and Developmental Biology, Monash University, Victoria, Australia
3. Department of Obstetrics and Gynecology, Hokkaido University Hospital, Sapporo, Japan
4. Department of Veterinary Pathology, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan