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
Organ transplantation people who die waiting, any potentially suitable organ must be considered. In 2016, a woman who was born without a uterus had a uterus successfully transplanted from a deceased donor. The donated uterus successfully sustained a pregnancy. In most countries there is a shortage of suitable organs for transplantation. Countries often have formal systems in place to manage the process of determining who is an organ donor and in what order organ recipients receive available organs. The overwhelming majority of deceased-donor organs in the United States are allocated by federal contract to the Organ Procurement and Transplantation Network (OPTN), held