“…In contrast to tumoral invasion, this trophoblastic invasion is precisely regulated, confined spatially to the endometrium, the first third of the myometrium, and the associated spiral arterioles and confined temporally to early pregnancy (Boyd and Hamilton, 1970). Expression of integrins (Damsky et al, 1992(Damsky et al, , 1994, cell adhesion molecules (Redman, 1997;Zhou et al, 1993Zhou et al, , 1997aZhou et al, , 1997b, and metalloproteases (Bischof et al, 1995;Damsky et al, 1992;Lala and Hamilton, 1996;Maquoi et al, 1997) throughout this migration has been well documented by immunohistochemistry and in situ hybridization. In addition, these extravillous trophoblasts express specific HLA antigens, such as HLA-G, which are directly involved in avoiding maternal rejection (Kovats et al, 1990;Le Bouteiller and Blaschitz, 1999).…”