W.A. Castro-Rendón, J.F. Castro-Álvarez, C. Guzmán-Martinez and J.C. Bueno-Sanchez. Blastocyst-endometrium interaction: intertwining a cytokine network. Braz J Med Biol Res 2006; 39: 1373-1385.

Figure 1. Model for the interaction between cytokines and mediators of inflammation associated with embryo implantation. The effect of estrogen (E2) is mediated by the nidatory action of leukemia inhibitory factor (LIF) in the endometrium, which is regulated by interleukin-1 (IL-1) and heparin binding-epidermal growth factor (HB-EGF). Both factors induce trophoblastic differentiation and angiogenesis through vascular endothelial growth factor (VEGF). Prostaglandin modulates IL-1 and possibly colony stimulating factor-1 (CSF-1) production. Both contribute to syncytiotrophoblast and anchoring cytotrophoblast differentiation. Aspirin (acetylsalicylic acid, ASA) acts in a selective manner on cyclooxygenase-1 (COX-1) and this could have an indirect effect on prostaglandin (PG) production by induction of COX-2.