Figure 5:

Two-wave hypothesis. We propose that there are two waves of NK that occupy and accumulate at the implantation site during pregnancy. The first wave of NK cells is observed during the decidualization process. The primary cells are proliferating trNK cells with cNK cells appearing to play a negligible role. In a second wave, cNK cells are recruited from the periphery during remodeling of the spiral arteries critical for placentation (Sojka et al, in press).