Embryo developmental and morphokinetic patterns in the domestic cat (Felis catus): associations with maternal age and SRT1720 supplementation during oocyte in vitro maturation

Abstract

This study describes embryo developmental progression and morphokinetic patterns in embryos derived from oocytes of young and aged domestic cats, a model for endangered felids, using a time-lapse monitoring system. Because maternal aging is associated with reduced oocyte competence, possibly linked to mitochondrial dysfunction that may impair fertilization and embryo development, the potential influence of the SIRT1 activator SRT1720 during in vitro maturation on embryo developmental progression was also evaluated under these conditions. Oocytes from young (1.13 ± 0.79 years) and old (7.0 ± 1.10) cats were matured in vitro with SRT1720 (1-μM, 0.1-μM, and 0.05-μM) and without, followed by in vitro fertilization. 8-Day embryo in vitro culture was noninvasively monitored using the MIRI® time-lapse system. Embryos from aged cats exhibited accelerated progression up to the morula stage; in contrast, embryos from young cats showed faster progression at later preimplantation stages and reached the hatched blastocyst stage. In young queens, embryos exposed to 0.1-μM showed numerically higher first cleavage and morula formation rates than controls, while 1-μM was associated with altered first cleavage timing and short cell cycles. In older queens, 0.1-μM maintained cleavage timing patterns comparable to untreated embryos but fail to produce hatched blastocysts, whereas 1-μM yielded a single hatched blastocyst despite signs of altered cell cycle dynamics. Overall, SRT1720 supplementation did not significantly influence embryo development under the tested conditions. Morphokinetic monitoring provided descriptive observations suggesting distinct age-related developmental profiles. These findings provide baseline information on feline developmental kinetics and may support further investigation of metabolic modulators in feline assisted reproduction.