Abstract Objective Recreational marijuana use is becoming increasingly widespread. With potential implications for fertility and embryonic development, we set out to evaluate the impact of THC exposure on the pre- and post-implantation embryo through embryonic stem cell proliferation, mitochondrial function and metabolism. Materials and Methods Mouse embryonic stem cells (ESCs) can be differentiated into epiblast-like cells (EpiLCs) using known in vitro methods via growth factors and cytokines. ESCs recapitulate important features of pre-implantation stem cells; EpiLCs model post-implantation features. ESCs and EpiLCs were exposed to a range of Δ9-THC concentrations: 0-100μM over 48 hours. Cell proliferation and viability were assessed via Trypan blue and...