Umbilical cord from and contains remnants of the yolk sac and allantois. It forms by the fifth week of development, replacing the yolk sac as the source of nutrients for the embryo. The cord is not directly connected to the mother's circulatory system, but instead joins the placenta, which transfers materials to and from the maternal blood without allowing direct mixing. The length of the umbilical cord is approximately equal to the crown-rump length of the fetus throughout pregnancy. The umbilical cord in a full term neonate is usually about 50 centimeters (20 in) long and about 2 centimeters (0.75 in) in
Uterus transplantation ovum and her husband's sperm, which was then implanted into the transplanted uterus. The uterus may have been damaged in the course of the caesarian delivery and it may or may not be suitable for future pregnancies. A regimen of triple immuno-suppression was used with tacrolimus, azathioprine, and corticosteroids. Three mild rejection episodes occurred, one during the pregnancy, but were all successfully suppressed with medication. Some other women were also reported to be pregnant at that time using transplanted uteri. The unnamed mother, who received a donated womb from a friend, said that she hoped the treatment would be refined