1. Department of Human Anatomy and Histoembryology, School of Basic Medical Sciences Southwest Medical University Luzhou Sichuan 646000 People's Republic of China
2. Affiliated Hospital of Traditional Chinese Medicine Southwest Medical University Luzhou Sichuan 646000 People's Republic of China
3. Department of Histology and Embryology Chongqing Institute of Neuroscience, College of Basic Medical Sciences, Third Military Medical University Chongqing 400038 People's Republic of China