Objective The malformation of spine is one of the commonest congenital malformation and its pathological changes associated with many diseases. Therefore, the development of spinal is an important part in the prenatal routine examination. The better understanding of the spine development process could be a reference for abnormal prenatal detection.Previous studies mainly rely on ultrasound and X-ray equipment.The advantages of ultrasound make it is the first choice for screening in the clinical examination, but its low tissue contrast and spatial resolution cannot meet the requirements of the clinical diagnosis.And Xrays,with the risk of radiation,can only distinguish ossification center of spine.As a non-invasive without radiation exposure technique, MR became popular tools for the research of assessing and monitoring fetal development. However, the question of when the ossification center of atlanto-axial vertebrae appears and could be detected by MR in human fetuses hasnt been fully answered. In order to address this question, we used the three-dimensional T2-weighted MRimaging technique to investigate the development process of ossification center in postmortem fetuses.