Talk:Mouse Estrous Cycle
From Embryology
http://www.plosone.org/article/info:doi%2F10.1371%2Fjournal.pone.0000382
Naturally occurring Foxp3+regulatory T cells play an important role in the inhibition of an immunological attack of the fetus. As implantation of the fetus poses an immediate antigenic challenge, the immune system has to prepare itself for this event prior to implantation.
