09-P022 An ex vivo model of placental development

The placenta facilitates nutrient and gas exchanges between the mother and growing fetus. It does this through highly branched embryonic blood vessels called villi. In the mouse, villi start to form when the allantois attaches to the chorion. This attachment is mediated through a thin layer of mesothelium on the chorion, which becomes indistinguishable from the allantoic cells after attachment. Abnormalities in placental development underlie human pathologies such as pre-eclampsia, miscarriages, and intra-uterine growth-retardation. The genetic and structural features of the human placenta are conserved in mice, and the murine placenta is well characterized invivo. However, there are no systems to study and manipulate the placenta exvivo. We hypothesized that co-cultures of pre-attachment chorions and pre-attachment allantoises will mimic early invivo events in placental development, under the correct culture conditions. Chorions and allantoises of wild type mouse embryos were dissected at somite stage 3–6, and were combined and cultured for 12, 24, and 36 h exvivo. We found that under ourculture conditions, the allantois attachedto the chorion, and the mesothelium was indistinguishable from the allantois. We will present our morphological and molecular characterization of this exvivo model. This model will further our knowledge of early placental development as it allows for invitro manipulation of the allantois and chorions prior to culture.