The Effect of Melatonin on The Developmental Potential and Implantation Rate of Mouse Embryos

Melatonin is a scavenger agent that has been used to promote in vitro embryo development. This study was designed to show the effects of melatonin on the quality and quantity rate of preimplantation mouse embryo development and pregnancy. In this experimental study, super ovulated, mated mice were killed by cervical dislocation to collect two-cell zygotes from the oviduct of pregnant 1 day NMRI mice. Zygotes were cultured to the hatching blastocyst stage and the numbers of embryos at different stages were recorded under an inverted microscope. The cleavage rates of two-cell zygotes were assayed until the blastocyst and hatching blastocyst stage in drops of T6 medium that contained either melatonin (1, 10, and 100×106, 10 and 100×109 M) or no melatonin. The cell numbers of blastocysts were determined by differential staining, implantation outcomes were studied, and development and pregnancy rate were compared by the Chi-square (development) and Fisher’s exact (pregnancy rate) tests. The addition of 10 and 100 nM melatonin to the embryo culture media promoted the development of the two-cell stage embryos to blastocyst and hatching blastocysts (p<0.01) and caused a significant increase in total cell number (TCN), trophoectoderm (TE), and inner cell mass (ICM) of the blastocysts (p<0.01). A difference was observed in the percentage of transferred embryos that were successfully implanted between the control and treatment groups (p<0.05). The data indicate that 10 and 100 nM of melatonin positively impact mouse embryo cleavage rates, blastocyst TCN, and their implantation. Therefore, melatonin at low concentrations promotes an embryonic culture system in mice.