As the gastrointestinal (GI) tract develops during the perinatal period, ENS and mucosal growth occurs along with the maturation of the intestinal barrier function. This period, along with the interactions with the microbial environment, nutrients, immunity are pivotal not only in health of the neonate but subsequent health beyond the neonatal period. Thus, there is a strong need to better understand the development of GI functions during the perinatal period and the role of environmental factors in the modulation of this development and subsequent disorders. Our axis is centered on the study of the mechanisms involved in gut and enteric nervous system (ENS) development and maturation during the perinatal period. Our goal is to identify molecular pathways important for gut and ENS development and to study the contribution of gut microbiota in these developmental processes. Herein, we ambition to address the pathophysiological mechanisms of GI-associated neurodevelopmental diseases including Hirschsprung disease (HSCR) and Autism Spectrum Disorder (ASD).