The ability of donkey sperm to induce oocyte activation and mule embryo development after ICSI.

Members of the Equus genus exhibit a fascinating capacity for hybridization, giving rise to healthy offspring. Mules, resulting from the mating of a mare with a jack, represent the most prevalent equid hybrid, serving diverse roles in our society. While in vitro embryo production, particularly through Intracytoplasmic Sperm Injection (ICSI), has rapidly gained significance in domestic horses, the in vitro production in other equids remains largely unexplored. Utilizing donkey sperm for fertilizing horse oocytes not only addresses this gap but also provides an opportunity to investigate donkey sperm's fertilization capability in vitro to further improve donkey ICSI. In this work, we initially studied the localization of donkey sperm Phospholipase C zeta (PLCζ) and assessed the sperm's capacity to induce pronuclear formation and maternal SMARCA4 recruitment upon injection into pig oocytes through ICSI. Subsequently, we investigated the injection of donkey sperm into horse oocytes, evaluating in vitro production up to the blastocyst stage using sperm from different jacks, including frozen and refrigerated samples. Distinct patterns of PLCζ localization were observed for donkey sperm cells compared to their horse counterparts. Additionally, donkey sperm exhibits a reduced ability to induce porcine oocyte activation. However, when injected into horse oocytes, donkey sperm demonstrated sufficient capability to induce oocyte activation as no discernible differences in cleavage or blastocyst rates are observed between in vitro produced mules and horse ICSI embryos. Our study not only delineates PLCζ localization in donkey sperm but also suggests potential differences in the ability to induce oocyte activation in pigs compared to horses while observing no distinctions in pronuclear recruitment of SMARCA4. Interestingly, donkey sperm remains sufficiently capable of inducing horse oocyte activation for in vitro mule blastocyst production.

Endogenous lysophosphatidic acid participates in vascularisation and decidualisation at the maternal-fetal interface in the rat.

Lysophosphatidic acid (LPA) affects several female reproductive functions through G-protein-coupled receptors. LPA contributes to embryo implantation via the lysophospholipid LPA3 receptor. In the present study we investigated the participation of endogenous LPA signalling through the LPA3 receptor in vascularisation and decidualisation, two crucial events at the maternal-fetal interface. Pregnant rats were treated with diacylglycerol pyrophosphate (DGPP), a highly selective antagonist of LPA3 receptors, on Day 5 of gestation. Pregnant rats received intrauterine (i.u.) injections of single doses of DGPP (0.1mgkg-1) in a total volume of 2µL in the left horn (treated horn) in the morning of GD5. DGPP treatment produced aberrant embryo spacing and increased embryo resorption. The LPA3 receptor antagonist decreased the cross-sectional length of the uterine and arcuate arteries and induced histological anomalies in the decidua and placentas. Marked haemorrhagic processes, infiltration of immune cells and tissue disorganisation were observed in decidual and placental tissues from sites of resorption. The mRNA expression of three vascularisation markers, namely interleukin 10 (Il10), vascular endothelial growth factor (Vegfa) and vascular endothelial growth factor receptor 1 (Vegfr1), was reduced at sites of resorption from Day 8. The results show that the disruption of endogenous LPA signalling by blocking the LPA3 receptor modified the development of uterine vessels with consequences in the formation of the decidua and placenta and in the growth of embryos.