Comparative implantation and placentation.

In all placental mammals, the establishment of an intimate contact between the embryo and the mother follows a succession of common critical steps whose chronology and timing may considerably vary from species to species. These processes present a great diversity based on the anatomy and the histology of the uterus, the developmental stage of the embryo at the time of implantation, and the endocrine and molecular interactions between the uterine and the embryonic tissues. This paper provides an overview of the general mechanical, endocrinological and cellular aspects involved in implantation in mammals with an emphasis on domestic species.