Effects of advanced maternal age on development of preimplantation mouse embryos obtained from delayed mating

Rodent embryos resulting from delayed mating grow more quickly than those resulting from normal mating. To clarify the effects of maternal age on this enhanced growth and rapid differentiation of mouse embryos obtained from delayed mating, we studied normal (0 h after ovulation) and delayed mating (6 h after ovulation) subgroups in two different age groups (middle-aged, 9-11 months; elderly, 13-15 months), and compared the number of cells and the proportion of blastocyst formed (morphologically advanced blastocysts) among them. In middle-aged female mice, preimplantation embryos derived from delayed mating progressed more rapidly than their normally mated counterparts. The number of cells and the proportion of blastocyst formed among embryos from delayed mating were almost 3 h ahead of those of normal embryos. In the delayed mating subgroup from elderly mice, an enhanced rate of development was not observed. There was no difference in development of normally mated embryos from middle-aged females compared to each counterpart from elderly female mice. Preimplantation mouse embryonic development from delayed mating may be affected by advanced maternal age.