The embryos were then transferred to recipient women. They had pregnancies when the recipient's cycle was from 4 days in front of to 3 days behind the donor's uterus at ovulation. This suggests a window of implantation of up to 7 days. Navot et al, in 1991 reported on donor embryo transfers done with 2-3 day old embryos on recipient cycle days 15-20 (artificial cycles controlled with meds).
Making the world better, one answer at a time. Catalysts are never consumed in the reaction. that's what makes them catalyst! not a reactant. they increase the rate of reaction by lowering the activation energy for the reaction. One of the ways to do this by providing an alternative route for the reaction to follow.
Catalysts and activation energy To increase the rate of a reaction you need to increase the number of successful collisions. One possible way of doing this is to provide an alternative way for the reaction to happen which has a lower activation energy. In other words, to move the activation energy on the graph like this: Adding a catalyst has exactly this effect on activation energy. A catalyst provides an alternative route for the reaction.