Context: Extracellular vesicles (EVs) derived from the oviductal fluid (oEVs) play a critical role in various reproductive processes, including sperm capacitation, fertilisation, and early embryo development. Aims: To characterise porcine oEVs (poEVs) from different stages of the estrous cycle (late follicular, LF; early luteal, EL; mid luteal, ML; late luteal, LL) and investigate their impact on sperm functionality. Methods: poEVs were isolated, characterised, and labelled to assess their binding to boar spermatozoa. The effects of poEVs on sperm motility, viability, acrosomal status, protein kinase A phosphorylation (pPKAs), tyrosine phosphorylation (Tyr-P), and in in vitro fertility were analysed. Key results: poEVs were observed as round or cup-shaped membrane-surrounded vesicles. Statistical analysis showed that poEVs did not significantly differ in size, quantity, or protein concentration among phases of the estrous cycle. However, LF poEVs demonstrated a higher affinity for binding to sperm. Treatment with EL, ML, and LL poEVs resulted in a decrease in sperm progressive motility and total motility. Moreover, pPKA levels were reduced in presence of LF, EL, and ML poEVs, while Tyr-P levels did not differ between groups. LF poEVs also reduced sperm penetration rate and the number of spermatozoa per penetrated oocyte (P < 0.05). Conclusions: poEVs from different stages of the estrous cycle play a modulatory role in sperm functionality by interacting with spermatozoa, affecting motility and capacitation, and participating in sperm–oocyte interaction. Implications: The differential effects of LF and LL poEVs suggest the potential use of poEVs as additives in IVF systems to regulate sperm–oocyte interaction.

The semen of boar is characterized by ejaculation in well-differentiated fractions with specific concentration, composition, and volume. The 'sperm-rich fraction' (SRF), the most concentrated seminal fraction, is habitually collected in insemination centers to make artificial insemination (AI) doses. The absence of the other fractions in AI doses could alter the uterine reaction to AI and not trigger essential responses that could maximize fertility. Thus, there is an urge to ascertain the impact of different ejaculate fractions on the uterus after AI to optimize the semen doses. This work analyzed specific parameters related to fertility in pregnant artificially inseminated sows (n = 15) with ac-cumulative fractions of the semen of boars (n = 6): F1, composed of the sperm-rich fraction (SRF); F2, composed of F1 plus the intermediate fraction; F3, composed of F2 plus the post-SRF. Non-inseminated sows (n = 5) were included as control (C). The different types of seminal dose did not affect the number of ovulated follicles (CL; corpora lutea, p > 0.05) but did affect the embryo development (p < 0.05). The proportion of embryos in morula stages was significantly higher in AI-F1 sows (84.4%, p < 0.05). Morulas and blastocysts were balanced in AI-F2 or AI-F3 (p > 0.05). Independently of the type of seminal dose (F1, F2, or F3), we observed by immunohistochemistry that AI significantly increased uterine vascularization, although with some anatomical differences. The cranial region of the uterine horns was significantly more vascularized in AI-F1 or AI-F2 sows (26.7 ± 2.3 and 28.6 ± 2.0%, respectively), and AI-F3 showed significantly less vascularization at that point (17.8 ± 1.6%, p < 0.05). To summarize, the synergistic effect of all ejaculate fractions accelerates embryo development, at least during the preimplantation period, and increases the uterine reaction to AI in certain parts of the uterus.

Artificial insemination (AI) is essential in intensive pig production, which significantly depends on semen quality from boars selected for health, genetics, and fertility. While AI aims to improve productivity, larger litters often result in smaller and less resistant piglets. Beyond fertility and genetic traits, boars also influence offspring health. This study investigated the relationship between sperm parameters of highly fertile boars and both reproductive outcomes and piglet physiological indicators. Multivariate analysis revealed significant paternal effects on blood markers reflecting organ function, including those of the pancreas, liver, and kidneys, as well as on glucose homeostasis, lipid metabolism, oxidative stress, protein and carbohydrate metabolism, muscle contraction, and neural signaling. Notably, sperm velocity was correlated with mitochondrial function, which is crucial for sperm motility, capacitation, DNA integrity, and embryo development—factors likely linked to healthier, more resilient offspring. Boars transmitting superior sperm velocity, erythropoiesis efficiency, and oxygen transport capacities produced piglets with better glucose regulation, growth, and resistance to neonatal hypoglycemia. These findings underscore the broader impact of sperm quality on offspring vitality and suggest that advanced sperm analysis could improve boar selection and enable more effective, health-oriented breeding strategies.

Las vesículas extracelulares (VEs), exosomas y micro vesículas son un tipo de estructuras heterogéneas presentes en la mayoría de los fluidos orgánicos incluyendo el fluido oviductal. Las VEs contienen varios compuestos derivados de la célula original, como proteínas, lípidos, ARNm, miARN y ADN. Las VEs en el oviducto son producidas por las células epiteliales y entre sus funciones se encuentran: interacción con los espermatozoides, mantener la viabilidad de estos, participar en la maduración de los ovocitos y en el proceso de fecundación. Durante la fecundación in vitro y, con el fin de mejorarla imitando las condiciones in vivo, numerosos investigadores han utilizado cultivos de células del epitelio oviductal bovino (CEOB) con notables mejoras. Estas células producen, entre otros componentes VEs, por ello, en este trabajo hemos planteado un estudio comparativo de VEs presentes en el fluido oviductal (FO) bovino recogido en momentos próximos a la ovulación (in vivo) y de aquellas VEs producidas en cultivos de CEOB a los 7 días de cultivo (in vitro) comparando el tamaño, la distribución de la población y la concentración de proteína en ambos tipos. Las VEs se identificaron mediante microscopía electrónica, su tamaño mediante dispersión de luz láser y la concentración de proteínas mediante el método Bradford. Los resultados mostraron que el tamaño de las VEs fue similar entre ambos grupos experimentales. Por otro lado, sí que se observaron diferencias en cuanto a la concentración de proteínas. Las VEs obtenidas in vivo contenían mayor cantidad de proteína en su cargo que en las VEs obtenidas in vitro. En cuanto a identificación de las VEs mediante microscopía electrónica de transmisión, solo pudieron ser observadas aquellas obtenidas in vivo. Este hecho podría deberse al lugar de dónde han sido recogidas, al método de cultivo de células epiteliales oviductales bovinas o la escasez en su producción.