Background
Our environment is replete with chemicals that can affect embryonic and extraembryonic development. Dioxins, such as 2,3,7,8-tetrachlorodibenzo-p<math><mrow><mi>p</mi></mrow></math>-dioxin (TCDD), are compounds affecting development through the aryl hydrocarbon receptor (AHR). Objectives: The
Discussion
We identified an AHR regulatory pathway in rats activated by dioxin affecting uterine and trophoblast cell dynamics and the formation of the hemochorial placenta. https://doi.org/10.1289/EHP9256.
Methods
Actions of TCDD were examined in wild-type and genome-edited rat models. Placenta phenotyping was assessed using morphological, biochemical, and molecular analyses.
Results
TCDD exposures were shown to result in placental adaptations and at higher doses, pregnancy termination. Deep intrauterine endovascular trophoblast cell invasion was a prominent placentation site adaptation to TCDD. TCDD-mediated placental adaptations were dependent upon maternal AHR signaling but not upon placental or fetal AHR signaling nor the presence of a prominent AHR target, CYP1A1. At the placentation site, TCDD activated AHR signaling within endothelial cells but not trophoblast cells. Immune and trophoblast cell behaviors at the uterine-placental interface were guided by the actions of TCDD on endothelial cells.