Gene expression during equine chorionic girdle development

We obtained placental issue between days 27 and 34 of pregnancy from matched mare and stallion pairs. We used whole transcriptome profiling in order to measure and compare gene expression in chorionic girdle trophoblast and adjacent regressing chorion at pregnancy day 27 (initiation of proliferation and prior to differentiation), day 30 (initiation of differentiation), day 31 (consolidation of differentiation and movement of cells) and day 34 (when the majority of the trophoblast cells have terminally differentiated into binucleate eCG-secreting trophoblast and have started to obtain invasive qualities and immunomodulatory capacities). Differentially expressed genes were then identified to determine functions and signalling pathways whose activity was modulated over this critical period of trophoblast development. A selection of genes and pathways were subsequently validated. Using agilient horse one colour array, gene expression in equine placental chorionic girdle tissue and matched chorion (as a control) at gestation days 27, 30, 31 and 34. 5 replicates of each time pont and each tissue for a total of 40 RNA samples. Two samples were excluded as significant outliers on a PCA visualization.