Avian embryo model of neuroblastoma. (IMAGE) CNRS Caption Avian embryo model of neuroblastoma. Physiological signals from embryonic tissues in which tumours develop cause some cells to acquire more aggressive traits, break away, and spread to remote sites, seeding metastases. Credit © MeLiS_Equipe Castellani Usage Restrictions May only be used to report on this research License Original content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.