Because the endometrial lining of the uterus secretes many different cytokines necessary for growth of the embryo, a new procedure has been developed to mimic the natural environment of the growing embryo using autologous (patient's own) endometrial cells in co-culture with the embryo. Endocell, a product developed by Genévrier Laboratories, received commercial authorization in France in 2011. It is the only system of autologous embryo-endometrium co-culture available on the actual market. The process consists of developing the embryo on a monolayer of the patient's own endometrial cells in order to favor its growth until the blastocyst stage (day 5) and to improve its implantation.