Implantation involves complex molecular interactions between implanting bla
stocysts and the hormonally primed uterus. Gene targeting allows the genera
tion of mice lacking a specific gene or genes and has proved to be of consi
derable value when combined with classical physiology in understanding many
biological questions, such as the process of implantation. In this article
, we review genes that have been demonstrated by gene targeting in mice to
be required in the uterus for implantation. In particular, we focus on a sp
ecific class of developmental control genes, the mammalian Hox genes, and t
heir role in this process. Lastly, we attempt to synthesize current knowled
ge about the genetic control of implantation and to build a working genetic
model for the implantation pathway.