Uterine fluid (UF) is essential for the development of preimplantation embryos and blastocyst implantation. UF is secreted by the endometrial glands and is composed of required substances for embryo development including metabolites, lipids, proteins, and hormones.
In placental mammals, trophoblast cells form the placenta post-implantation which then provides nutrients and gas exchange for the developing fetus. The importance of UF post-implantation is not well understood.
Marsupials have a short gestation, giving birth to highly altricial young which continue development in the mother’s pouch. The fat-tailed dunnart (Sminthopsis crassicaudata) has a gestational period of ~14 days, and breeds well in captivity, making it an excellent model species to study marsupial reproduction. Fat-tailed dunnart embryos implant into the uterus for ~2 days prior to birth, indicating that the composition of marsupial UF can maintain embryo development until late gestation.
Aims: To improve embryo culture conditions, we aim to identify conserved components of UF in both mice (eutherian) and fat-tailed dunnarts (marsupial) over the gestational time course.
Methods: UF for both species has been collected at early-, mid- and late-gestation. To compare UF of these species, a multi-omics approach has been taken with metabolomics, proteomics and lipidomics being measured.
Results: All omics indicated changes in molecular composition of uterine fluid throughout gestation. Here we describe proteins, metabolites and lipids which are similarly increased, decreased or are stable in mouse and dunnart. In particular, conservation of lipid dynamics highlights its potential importance for all stages of gestation.
Conclusion: These analyses will enhance our understanding of how UF impacts embryo development across gestation, even after implantation, and will advise on components required for embryo culture. This study will have future implications on assisted reproductive technologies in eutherian and marsupial species which can be exploited for human fertility and conservation of threatened animals.