1. Division of Histology and Embryology, International Joint Laboratory for Embryonic Development & Prenatal Medicine, Medical College, Jinan University, Guangzhou, China;
2. Department of Pathology, The First People’s Hospital of Foshan, Foshan, China;
3. Department of Gynaecology and Obstetrics and
4. Department of Pediatrics and Neonatology, Institute of Fetal-Preterm Labor Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, China;
5. Institute of Laboratory Animal Science, Jinan University, Guangzhou, China; and
6. Key Laboratory for Regenerative Medicine of the Ministry of Education, Jinan University, Guangzhou, China