The fibrinolytic system (plasminogen–plasmin system) is involved in the process of fertilisation, although its function is not fully clarified. This study showed how different components of the plasminogen–plasmin system act in mouse species. Specifically, tissue plasminogen activator (tPA) seems to be necessary for the success of in vitro fertilisation (IVF) but not in vivo. These findings suggest that the addition of exogenous tPA during IVF treatments could be useful under specific circumstances.

Paternal genetic alterations through male gamete (sperm) may influence the embryo quality and reproductive outcome. This study investigated the response to paternally transmitted DNA lesions on genetic integrity and metabolism (the chemical processes that occur within the cell in order to maintain life) in early mouse embryos. Observations from this study indicate that the genetic integrity and metabolic behaviour of the embryos are influenced by paternally transmitted DNA lesions.

The follicular environment is essential for the oocyte to acquire competence to develop into a high quality embryo. In this work, we identified metabolites such as glucose, pyruvate, cholesterol and estrogen, as well as metabolic and stress pathways, as important factors in achieving this ability. These data will contribute to identifying follicles that are prone to generating embryos with higher viability.

Oocyte development is a highly complex process. Lipid composition of oocytes derived from different follicles sizes and their relationship with follicular fluid molecules, embryo development and blastocyst lipid deposit were identified. We suggest that maintaining the exposure of the oocyte to the follicular microenvironment allows oocytes to proceed with events that are necessary to reach maturity and the positive impact of lipid accumulation for development may be seen as a necessary step to the forthcoming intense proliferative activity of the growing embryo.

If the DNA is damaged in oocytes, what can we do to save them? In this research, we found that co-culturing with certain concentrations of Roscovitine and TSA can help porcine oocytes recover from DNA damage and proceed to maturation and development. This can be used to improve the living capability of oocytes in vitro and to inspire more possibilities of combined treatment.

Cell type-specific RNA sequencing (RNA-Seq) of equine endometrial biopsies from Day 12 of pregnancy and the corresponding day of the oestrous cycle revealed distinct gene expression patterns in luminal epithelium, glandular epithelium and stromal areas, which was compared with RNA-Seq data obtained for whole biopsy samples.

This study showed the dynamics of 5mC and 5hmC in developing PGCs and the effects of Tet1 on the development of PGCs. Knockdown of Tet1 reduced the process of DNA demethylation and damaged PGC development. This study will shed important light on the mechanism by which Tet1 affects PGC global DNA demethylation and methylation state of Dazl.

Cryopreservation may reduce embryo developmental competence. The aim of this study was to evaluate the effect of supplementing in vitro culture media and/or vitrification solutions with resveratrol on embryo quality. The vitrification and warming process increased active mitochondria and mitochondrial superoxide production, but the addition of resveratrol, either to the IVC medium or to the vitrification solution, helped embryos to partially recover their initial ‘quieter’ state (i.e. lower oxidative metabolism).

Cumulus­–oocyte complex expansion is essential for ovulation and fertilisation. This study revealed that cumulus area is not altered in mice with oocyte-specific deletion of C1galt1 and Mgat1, despite a reduction in hyaluronan and other molecules associated with cumulus expansion. A minimum threshold may exist for supporting cumulus expansion. Oocyte-secreted factors may be affected by the deletions, causing altered cumulus composition.

Using stem cell technology, a group of surrogate males that produce donor sperm were created for the first time in the dromedary camel. This technology has the potential to disseminate a favoured genotype in species where artificial insemination is not feasible due to the lack of effective semen freezing protocols. The treatment of the surrogate male’s testis with a protein, DBA lectin, is critical for the success of this process.

Temperature fluctuations induce molecular and morphological changes in aquatic organisms. In this study, we analysed embryo development under conditions of thermal stress and showed that reduced embryo viability and increased larval malformations are probably related to modifications in the expression of caspase-3 during early development, even with an increase in heat shock protein 70 levels. Understanding the effects of thermal stress could establish critical temperature limits during development, improving the quality of fish farming.

The involvement of lipid metabolism during porcine oocyte maturation is poorly understood. The aim of this study was to assess the effect of media carbohydrate composition on the modulation of lipid metabolism. The results revealed that stimulation of fatty acid oxidation was only beneficial when levels of carbohydrates were deficient. The findings will inform future media refinements to improve the IVM of porcine oocytes.

Mitochondria are vital for generating the energy an early embryo requires. In horse embryos, the number of mitochondria only increases when the embryo starts to expand and undergo cell differentiation; surprisingly, a low mitochondrial number before this time is not associated with embryo death. Understanding exactly when, and in which cells, mitochondrial replication starts may yield novel markers for a ‘healthy’ embryo.

The expression of glycoepitopes may be involved in the regulation of maternal immunity preventing rejection of spermatozoa. Seminal plasma separated by polyacrylamide gel electrophoresis with sodium dodecyl sulphate were probed with lectins specific to fucose and sialic acid. Differential expression of α2,3-linked sialic acid was found in 86% of analysed bands, contrary to the observed differences for other glycoepitopes. Mass spectrometry analysis focussed on the identification of proteins carrying glycans with immunomodulatory epitopes.

Mimicry, a phenomenon to date studied only in the context of autoimmune diseases, has been proposed to be a reason for immune infertility as well, owing to the similarity of proteins in bacteria and spermatozoa. The present study successfully validated this hypothesis by isolating the bacterial counterpart of a sperm protein and employing it for the treatment of infertility induced by sperm-impairing bacteria, thereby opening many therapeutic avenues.

Ensuring the pregnancy status of a sow as early as possible after breeding has become a top priority for profitable pig production. Comprehensive proteome profiling of sow serum during early pregnancy stages revealed several differentially expressed proteins including some significant pregnancy-related proteins. They could serve as potential biomarkers for pregnancy diagnosis as early as Day 12 after breeding, which would facilitate more-economic pig production.