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Despite extensive research on the cryopreservation of stallion semen, the process still requires improvement. Several diluent additives have been developed to overcome cryopreservation issues, however, semen from valuable individuals often shows poor quality after thawing. Mesenchymal stem cells (MSCs) are regarded as factors that may play an important role in the regenerative process of sperm by secreting extracellular vesicles (EVs) that are actively involved in intercellular communication, tissue repair and cell membrane maintenance. The study aimed to determine the effect of the addition of EV-MSCs obtained from equine adipose tissue on various parameters of cryopreserved stallion semen. All cells met the minimum criteria established by the ISCT, being a characteristic surface profile of the presence of CD90 and lack of MHC II, differentiation into three mesodermal lineages, and adherence. EVs were collected from the expanded cells by ultracentrifugation, and their characteristics were confirmed using nanoparticle tracking analysis (NTA) and flow cytometry to detect CD63 and CD81 antigens. Semen was collected from 11 stallions of the Hucul breed, and each parameter of sperm quality with (25 µg/ml, 50 µg/ml) and without EV addition (motility, morphology and viability) was analyzed. The results showed statistically significant differences in sperm motility, progressive movement and viability following EV treatment. While the amplitude of lateral head displacement (ALH) and morphology parameters did not change, the addition of EVs does not affect these sperm features. The results provide an initial insight into the role of EVs in the maintenance and regeneration of horse sperm after cryopreservation-induced shock. [ABSTRACT FROM AUTHOR]

The evaluation of oocytes and zygotes, based on their size, shape and morphology, is a valuable tool for predicting subsequent embryo development. While this assessment is non-invasive and made possible with time-lapse monitoring systems, not all the assessment criteria used for zygotes with pale cytoplasm can be used for domestic cat zygotes, which have dark cytoplasm. In this study, feline presumptive zygotes were evaluated for shape, size, and morphology. Measurements were also made of the diameter of the entire zygote, its cytoplasm, and the zona pellucida. Differences in the dataset were assessed using the generalized linear model (GLM) procedure. While there was no relationship between a combination of the tested parameters with the potential for cleavage, blastocyst development, and hatching, the parameters of the shape and size of the entire oocyte, and of the zona pellucida, were related to the development potential. The results presented in this study indicate that the assessment procedure for human zygotes has to be adjusted to be used in the cat model, however the relationship between measurements of the diameter of presumptive feline zygotes and the thickness of zona pellucida with their developmental potential deserves further investigation to optimize assessment of cat presumptive zygotes. [ABSTRACT FROM AUTHOR]