The Implantation Window in Humans after Fresh or Frozen-Thawed Embryo Transfers

In mammals, the opdmum time for embryo transfer greatly depends upon the species. In rodents, a high synchrony between the donor and the recipient is required.1,2 In sheep3 and catde4 too, better results are obtained with synchronous transfers. In other species, such as pigs5, mares6 and monkeys7, an asynchrony up to one or even two days is possible.