Browsing by Subject "Monospermy"

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    Manipulation of bicarbonate concentration in sperm capacitation media improves in vitro fertilisation output in porcine species
    (BioMed Central, 2019-03-11) Soriano-Úbeda, Cristina; Romero Aguirregomezcorta, Jon; Matas Parra, Carmen; Visconti, Pablo E.; García Vázquez, Francisco Alberto; Anatomía y Anatomía Patológica Comparada; Facultad de Veterinaria
    Background. The in vivo concentration of bicarbonate (HCO3−), one of the essential sperm capacitating effectors, varies greatly in the different environments sperm go through from cauda epididymis to the fertilisation site. On the contrary, porcine in vitro sperm capacitation and fertilisation media usually contains a standard concentration of 25 mmol/L, and one of the main problems presented is the unacceptable high incidence of polyspermy. This work hypothesised that by modifying the HCO3− concentration of the medium, the output of in vitro sperm capacitation and fertilisation could be increased. Results: Once exposed to the capacitation medium, the intracellular pH (pHi) of spermatozoa increased immediately even at low concentrations of HCO3−, but only extracellular concentrations of and above 15 mmol/L increased the substrates protein kinase A phosphorylation (pPKAs). Although with a significant delay, 15 mmol/L of HCO3− stimulated sperm linear motility and increased other late events in capacitation such as tyrosine phosphorylation (Tyr-P) to levels similar to those obtained with 25 mmol/L. This information allowed the establishment of a new in vitro fertilisation (IVF) system based on the optimization of HCO3− concentration to 15 mmol/L, which led to a 25.3% increment of the viable zygotes (8.6% in the standard system vs. 33.9%). Conclusions: Optimising HCO3− concentrations allows for establishing an IVF method that significantly reduced porcine polyspermy and increased the production of viable zygotes. A concentration of 15 mmol/L of HCO3− in the medium is sufficient to trigger the in vitro sperm capacitation and increase the fertilisation efficiency in porcine.
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    Pig in vitro fertilization: where are we and where do we go?
    (2019) Romar, Raquel; Cánovas, Sebastián; Matás, Carmen; Gadea, Joaquín; Coy, Pilar; Fisiología
    The pig is an important livestock animal. Biotechnological interest in this species has increased due to its use, among others, in the generation of transgenic animals for use in biomedicine based on its greater physiological proximity to the human species than other large domestic animals. This development has paralleled an improvement in Assisted Reproduction Techniques (ART) used for this species. However, the ability to generate animals from embryos produced entirely in vitro is still limited and a wide margin for improvement remains. Here we review the procedures, additives, and devices used during pig in vitro fertilization (IVF), focusing on the main points of each step that have offered the best results in terms of increased efficiency of the system. The lack of standardized protocols and consensus on the parameters to be assessed makes it difficult to compare results across different studies, but some conclusions are drawn from the literature. We anticipate that new physiological protocols will advance the field of swine IVF, including induction of prefertilization ZP hardening with oviductal fluid, sperm preparation by swim-up method, increased viscosity through the addition of inert molecules or reproductive biofluids, and the incorporation of 3D devices. Here we also reflect on the need to expand the variables on which the efficiency of pig IVF is based, providing new parameters that should be considered to supply more objective and quantitative assessment of IVF additives and protocols.