1. Division of Histology and Embryology; Jinan University School of Medicine; Guangzhou People's Republic of China
2. Ministry of Education Key Laboratory for Regenerative Medicine, School of Biomedical Sciences; Chinese University of Hong Kong; Shatin Hong Kong
3. Department of Radiology, VA San Diego Healthcare System; San Diego California
4. Department of Radiology; University of California San Diego, San Diego Medical Center; San Diego California