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.
Enzymes are used in the chemical industry and other industrial applications when extremely specific catalysts are required. Enzymes in general are limited in the number of reactions they have evolved to catalyze and also by their lack of stability in organic solvents and at high temperatures.nzymes differ from most other catalysts by being much more specific. Enzyme activity can be affected by other molecules: inhibitors are molecules that decrease enzyme activity, and activators are molecules that increase activity.