- Pp. xviii-xivii (30)Gérard Chaouat
In this introduction, we briefly review the “evolution of viviparity” as would say Peter Medawar, encompassing not only the vertebrates but the (very early) invertebrates, in order to see the cohabitation with the adaptive and innate immune system in an evolutionary perspective. We personally believe this approach is of importance, since viviparity and the “allograft problem” did not emerge AFTER the adaptive immune system, but LONG before, as seen for example with … placental velvet worms. Even if the placentae in such species are obviously not as complex as mammalian ones, they are “non self allografts”. Thus, they, and other aspects, lead to heretic questions which might lead to reconsider the approach of the foeto maternal relationship, too often seen as a confrontation rather than a symbiosis/cohabitation.