Abstract

Thein vitroculture of domestic cat embryos without the zona pellucida affects theirimplantation capacity. MicroRNAs (miRNAs) have an important role in embryo-maternalcommunication and implantation. The objective of this study was to evaluate the expression ofspecific miRNAs in domestic cat blastocysts cultured without the zona pellucida. Twoexperimental groups were done: (1) domestic cat embryos cultured with the zona pellucida(zona intact control group, ZI); and (2) cultured without the zona pellucida (zona free group,ZF). The cleavage, morula and blastocyst rates were evaluated. The blastocysts and their spentmedium were used for miRNA expression analysis using RT-qPCR (miR-21, miR-24, mi25,miR-29, miR-96, miR-98, miR-103, miR-191, miR-196, miR-199, miR-130, miR-155andmiR-302). The pre-mature microRNAs (pre-miRNAs) and miRNAs were evaluated in theblastocysts and only miRNAs were evaluated in the spent medium. No differences wereobserved in the cleavage, morula and blastocyst rates between the ZF and ZI groups (P>0.05).For miRNAs analysis,miR-103andmiR-191had the most stable expression and were selectedas internal controls. ZF blastocysts had a higher expression ofmiR-21,miR-25,miR-29andmiR-199and a lower expression ofmiR-96than their ZI counterparts (P<0.05). Furthermore,higher levels ofmiR-21,miR-25andmiR-98were detected in the spent medium of ZFblastocysts (P<0.05). In conclusion,in vitroculture of domestic cat embryos without the zonapellucida modifies the expression ofmiR-21,miR-25,miR-29,miR-199andmiR-96at theblastocyst stage and the release ofmiR-21,miR-25andmiR-98.