I think you need to look at the great differences between the ruminant (cattle) and human placenta. There is a much greater barrier between maternal and fetal blood in the bovine compared to the human and the products of the placental layers are quite different. I admit that I do not know the answer to your questioin, but I would start by looking at different layers of placental cells.
Thank you . I found relation between progesterone hormone and infection with Brucellea by immunohistochemistry assay. If hormone important in infinity of Brucellea with placenta of women