**1.2 Collection of placental tissue**

All placentas from normotensive pregnant women were delivered by cesarean section, without labor and were examined macroscopically and processed within 10 min of delivery. Fragments of approximately 5 × 5 cm were immediately removed from the central region of the placenta, constituting samples of the villous cytotrophoblast and the syncytiotrophoblast region in contact with the maternal side (basal plate). After collection, the trophoblastic tissue was washed in buffered saline (PBS) and separated from the decidual layer that is normally adhered to the basal plate. The terminal portions of the villi were evidenced in PBS (the villi were seen floating freely in the liquid) and dissected in small sections to constitute explants.
