The Fallopian tube: Biosensor and dynamic regulator of preimplantation development

The Fallopian tube (also called the oviduct) provides the physiological site for fertilization and early embryonic development in mammals, yet its role in shaping preimplantation developmental competence remains incompletely understood. Although assisted reproductive technologies (ARTs) have enabled millions of successful pregnancies, most ART procedures bypass the oviduct, eliminating early embryo-maternal interactions that occur in vivo. Evidence across mammalian species demonstrates that the oviduct is not a passive conduit, but a dynamic tissue that regulates embryo transport, modulates immune and metabolic responses, and secretes stage-specific factors that influence embryonic development. Disruption of oviductal signaling impairs preimplantation development and leads to early pregnancy loss, highlighting the importance of a functional oviductal environment. Moreover, embryos actively send signals to the oviduct, eliciting stage-specific transcriptional and proteomic responses, indicating reciprocal communication during early pregnancy. Data suggest that embryos generated by different ART approaches (such as somatic cell nuclear transfer or artificial insemination) exhibit distinct molecular and metabolic profiles, raising the possibility that embryo source and quality may uniquely shape uterine epithelial responses following transfer. In this review, we provide evidence supporting the oviduct as an active regulator of preimplantation embryonic development, discuss the consequences of bypassing the oviduct in ART, and highlight current experimental models and knowledge gaps. Defining how the oviduct functions as a biosensor of embryo quality will be critical for understanding early pregnancy loss and refinements for ARTs.