Molecular insights to the sperm–cervix interaction and the consequences for cryopreserved sperm

Warr, Sophie
University of Sydney



The ovine cervix presents a unique barrier to frozen-thawed ram spermatozoa, negatively impacting pregnancy rates following cervical artificial insemination (AI). The reduced capacity of frozen-thawed spermatozoa to navigate the ovine cervix is hypothesised to be related to alterations in their molecular profile following seminal plasma exposure and cryopreservation, changing communication with the female environment. However, the molecular mechanisms underlying sperm-cervix interactions are yet to be defined. Previous bovine studies have utilised a novel ex vivo cell culture model to show changes in the transcriptome of endometrial uterine explants following exposure to spermatozoa and seminal plasma. Furthermore, transcriptomics has been used to describe the gene profile of cervical explants of ewes from different breeds, known to have varied fertility following cervical artificial insemination with frozen-thawed semen. However, to date, this model has yet to compare the transcriptomic response of ovine cervical explants to phenotypically different sperm types, such as fresh and frozen ram sperm. Before a study design of this nature could be conducted, it is first important to validate the model for use in ewes and with ram spermatozoa. As such, in the present study, we aimed to validate the use of this model in identifying genes expressed in ovine cervical explants following treatment with ram spermatozoa. Cervical explants (8mm x 8mm; n=2) were collected from Merino ewes (n=6) post-mortem and cultured with frozen-thawed spermatozoa (pooled sample of n=3 rams). Preliminary next-generation RNA-. These results indicate that this model is an appropriate tool for studying the sperm-cervix interaction and that even after preliminary analysis, the presence of sperm may alter cervical gene expression in the ewe. Further research can now apply this model to varying ram sperm phenotypes to try and further our understanding of the interaction between spermatozoa and the female environment. Genes of interest may reveal molecular candidates which influence cervical transit, and the fertility of frozen-thawed sperm following cervical AI