Endometrium and embryo implantation

Implantation of the embryo into the maternal endometrium represents a crucial step in the reproductive process. It results from a cascade of finely tuned events. Despite recent progress in the field, many points still require clarification. This special issue offers a broad coverage of the latest findings. New concepts and applications are presented which are based on data strongly suggesting that both embryo implantation and uterine receptivity are controlled, primarily, though not exclusively, by locally acting growth factors and cytokines. Different processes are also studied, such as the MMPs expression regulating the trophoblast invasion, or the possible secretion of sHLA-G molecules by human embryos and its correlation to a successful pregnancy. Further points under discussion are the chromosomal imbalance leading to embryonic mortality, and the potential of the baboon model to study embryo implantation. Finally, a comparative survey is given of the general mechanical, endocrinological and cellular aspects involved in implantation in mammals. Clinicians as well as basic researchers will find this special issue to be a valuable source of new insights.