The fertility of boar semen stored in diluent is known to decline, but the reasons why are unclear. We applied cluster analysis to sperm movement characteristics recorded under fertilising conditions and found that during storage the sperm subpopulation displaying a fast linear movement in response to the capacitating stimulus bicarbonate declines as a percentage of the total population. Therefore, the loss of fertilising ability may be due to a stepwise inactivation of bicarbonate-dependent signalling pathways.

Adhesion molecules are thought to be highly important in stem cell niches including the spermatogonial stem cell niche. Here, we investigate the expression of claudin-8, a tight-junction protein, in the testis, and show expression in undifferentiated spermatogonia and associated Sertoli cells. Our findings suggest a role for claudin-8 in the cellular interaction between those cells, and in the regulation of self-renewal and differentiation processes.

A novel direct bovine embryo-tagging system has been developed using polysilicon barcodes. This system allows the collective culture of embryos from different origins whilst preserving their pedigree, and facilitates the production of embryos from live animals of high genetic merit.

The glycoprotein mucin 1, expressed on the uterine epithelia during the non-receptive phase, acts as an implantation barrier to prevent embryo attachment onto the endometrium. Opposite expression patterns were found for microRNA (miRNA)-199a and mucin 1 during early pregnancy in mice and it was confirmed that mucin 1 is a direct target of miRNA-199a because mucin 1 expression is suppressed by miRNA-199a. The result suggests that miRNAs may serve as a novel strategy to assist clinical treatment in human implantation failure.

Low birthweight is a risk factor for adverse metabolic health. We investigated the relationship between prenatal and early postnatal growth trajectories and body composition in intrauterine growth-restricted (IUGR) and normal birthweight lambs of both sexes and showed that although IUGR lambs grew faster they remained smaller at weaning, but gender had the major influence on adiposity. Thus, prenatal growth status and gender are both likely to influence carcass composition and offspring health.

In our study, we investigated the effects of estrogen (E2) and estrogenic compounds on the regulation and localisation of Sprr2a protein in the mouse uterus. We concluded that Sprr2a protein is up-regulated by E2 via its nuclear estrogen receptors and also sensitively induced by BPA and OP, indicating that Sprr2a protein is a true E2-responsive protein in the mouse uterus. Our study proposes that Sprr2a protein can be valuable marker to predict and assess estrogenic activity in the uterus and offers useful tool to investigate unique regulatory mechanisms in non-squamous epithelia different from that in squamous epithelia.

In this work the essential tools for testicular germ cells transplantation were investigated in two flatfish species. The turbot, a domesticated species, was used as recipient and the Senegalese sole, a species whose reproduction in captivity is only guaranteed by wild broodstocks, as donor. The results of this work highlight the potential of germinal cell biotechnology in aquaculture and encourage further studies in the field of xenogenic transplantation for flatfish.

When optimising conditions for the maintenance of human embryonic stem cells the focus has been on maintaining pluripotency. In contrast, there has been little work assessing other cell indicators, such as metabolism. Here, carbohydrate utilisation and amino acid turnover were used to show that culture conditions significantly impact metabolism, and that commonly used culture supplements could alter nutrient use and biosynthesis without affecting pluripotency. The use of conditions that alter cell physiology may hamper future application of these cells and analysis of metabolism should be used when cell quality is assessed.

Most attempts to introduce individual culture in cattle embryos have shown a reduction in development from a typical 25–35% blastocysts in group culture to less than 10% in individual culture. However, we observed that the very simple act of using serum-free culture medium based on BSA and ITS unexpectedly led to high blastocyst development in individual culture. The development of a semi-defined individual culture system is not only an important tool for research laboratories and practitioners working with bovine IVF; in addition this study upgraded the value of bovine embryos as a model for human IVF.

Knowledge of the changes that occur in spermatozoa during the process of fertilisation can be keys to determining the reproductive potential of males. We observed changes in sperm motility patterns and membrane fluidity after incubation of sperm samples in IVF media. These changes did not occur in all spermatozoa, enabling the identification of various sperm subpopulations. The distribution of these subpopulations was found to be related to fertilising ability.

We investigated the effect of mechanical stimuli on mouse embryonic development from the 2-cell to blastocyst stage using mechanical vibration systems (MVSs). The MVS transmitted mechanical vibration power efficiently to embryos and resulted in a significant decrease in development to the morula or blastocyst stage after 2 days. These results suggest that mouse embryos are more sensitive to physical stimuli than human or pig embryos because of their thinner zona pellucida.

Blastocyst development in the well-of-the-well (WOW) culture system is better than in conventional culture systems with the same embryo number. To compare the concentration of chemical factors between conventional and WOW culture, a model was constructed to calculate concentrations. The findings suggest that the WOW culture system is better than conventional group culture because of increased final concentrations of autocrine factors and higher diffusion kinetics of waste materials.

The combination ratio and dose of gonadotropins are key factors for IVF success. However, the dose-dependent effects of gonadotropins on rates of oocyte maturation, fertilisation and early embryo development in vitro remain unknown. The results of the present study could be applied to therapeutic clinical stimulation protocols to help improve IVF success rates.

Nlrp4g is a member of the Nlrp gene family associated with innate immunity and reproduction in the mouse. The aim of the present study was to analyse the expression pattern and protein localisation of Nlrp4g and the effect of Nlrp4g knockdown on oocyte maturation. We found that Nlrp4g is an oocyte-specific gene but dispensable for oocyte maturation. These data are essential for understanding the molecular mechanism of oogenesis and oocyte maturation in mammals.