An emerging concept in female reproduction is the role of endocannabinoids, a group of endogenously produced lipid mediators that bind to and activate cannabinoid receptors. Although adverse effects of cannabinoids in female reproduction have been implicated for years, the mechanisms by which they exert these effects remained elusive. With the identifi cation of cannabinoid receptors, endocannabinoid ligands, their key synthetic and hydrolytic pathways, and the generation of knockout mouse models for cannabinoid receptors, a wealth of information is now available regarding the signifi cance of cannabinoid/endocannabinoid signaling in early pregnancy. This review focuses on various aspects of endocannabinoid signaling in preimplantation embryo development and activation, and uterine differentiation during the periimplantation embryouterine dialog. It is hoped that a deeper understanding will lead to potential clinical applications of the endocannabinoid system as a target for regulating female fertility.K EYWORDS: cannabinoid/endocannabinoid , embryo deve lopment , embryo oviductal transport , implantation , mouse

In the online version of this article, the right axis of the graph in Figure 1a was missing its label. It should be labeled 'average litter size.' Also in the online version, the link for Figure 2 was incorrect. This has now been corrected.