RT Journal Article T1 Comparative evaluation of three culture media for domestic cat in vitro embryo production and their effects on blastocyst development A1 Munoz-Maceda, Ana A1 Camacho, Eva Pericuesta A1 Priego González, Andrea A1 Núñez-Puente, Carolina A1 de los Reyes, Nuria Martínez A1 Cerdeira Lozano, Joaquín Vicente A1 Sánchez Rodríguez, Ana A1 Ramos-Ibeas, Priscila A1 Rizos, Dimitrios A1 Gutiérrez-Adán, Alfonso A1 Roldan, Eduardo R.S. A1 Sánchez Calabuig, María Jesús AB In vitro embryo production (IVP) in felid species faces difficulties derived from their conservation status, challenging reproductive traits and low success rates during in vitro maturation (IVM), fertilization (IVF) and culture (IVC). This study aimed to evaluate different IVC strategies for domestic cat IVP, as a model to improve assisted reproduction techniques (ARTs) in wild felids. Three IVC media were compared: (i) synthetic oviductal fluid (SOF) supplemented with fetal bovine serum (“FBS”); (ii): SOF supplemented first with bovine serum albumin (BSA), followed by FBS addition (“BSA-FBS”); and (iii): a commercial IVC human medium (IVC-CULT®) (“COM”). A total of 1064 in vitro matured cat oocytes were fertilized with frozen-thawed epididymal spermatozoa, and 813 presumptive zygotes were cultured in the three experimental groups. Expanded blastocysts (n = 108) were snap-frozen or fixed for differential cell count and quantitative analysis of pluripotency-related gene expression. One-way ANOVA was used to assess differences in IVP rates and blastocyst developmental parameters. No significant differences in cleavage or blastocyst rates were found among groups, nor in total blastomere count (P > 0.05). However, the FBS group showed higher SOX2 pluripotency marker expression compared to the other groups, while BSA-FBS exhibited a more balanced SOX2/OCT4 ratio, linked to blastocyst competence in other species. Furthermore, a tendency was found towards a lower proportion of cells in the inner cell mass (ICM) in the FBS group. Our results suggest that elevated SOX2 expression alone may not reflect improved developmental competence in the domestic cat blastocysts. Instead, early BSA supplementation followed by FBS might enhance ICM differentiation, benefiting first from BSA's fatty acids and later from FBS's antioxidants and growth factors. Lastly, the commercial medium yielded comparable embryonic developmental outcomes to BSA-FBS, offering a viable alternative. Thus, this research represents a contribution to the refinement of IVP protocols in the domestic cat, promoting standardization that could be adapted for wild feline conservation PB Elsevier SN 0093-691X YR 2026 FD 2026 LK https://hdl.handle.net/20.500.14352/124396 UL https://hdl.handle.net/20.500.14352/124396 LA eng NO Munoz-Maceda, A., Camacho, E. P., Priego-Gonzalez, A., Núñez-Puente, C., de los Reyes, N. M., Cerdeira, J., Sanchez-Rodriguez, A., Ramos-Ibeas, P., Rizos, D., Gutiérrez-Adán, A., Roldan, E. R. S., & Sánchez-Calabuig, M. J. (2026). Comparative evaluation of three culture media for domestic cat in vitro embryo production and their effects on blastocyst development. Theriogenology, 249. https://doi.org/10.1016/J.THERIOGENOLOGY.2025.117641 NO Credit authorship: contribution statement Ana Munoz-Maceda: Writing – original draft, Methodology. Eva Pericuesta Camacho: Supervision, Methodology. Andrea PriegoGonzalez: Writing – original draft, Methodology. Carolina Núnez- ˜ Puente: Methodology. Nuria Martínez de los Reyes: Methodology, Data curation. Joaquín Cerdeira: Writing – review & editing, Supervision, Methodology, Funding acquisition. Ana Sanchez-Rodriguez: Writing – review & editing, Methodology, Investigation, Conceptualization. Priscila Ramos-Ibeas: Writing – review & editing, Supervision, Formal analysis, Data curation, Conceptualization. Dimitrios Rizos: Writing – review & editing, Validation, Supervision, Investigation, Funding acquisition, Conceptualization. Alfonso Gutierrez-Ad ´ an: ´ Writing – review & editing, Validation, Supervision, Data curation, Conceptualization. Eduardo R.S. Roldan: Writing – review & editing, Validation, Supervision, Investigation, Conceptualization. María Jesús Sanchez-Calabuig: ´ Writing – review & editing, Validation, Supervision, Methodology, Investigation, Funding acquisition, Formal analysis, Data curation, Conceptualization. NO Comunidad de Madrid NO Ministerio de Ciencia, Innovación y Universidades (España) DS Docta Complutense RD 16 dic 2025