Umbilical cord is used in place of a bone marrow transplant in the treatment of blood disorders such as leukemia, with donations released for transplant through one registry, Netcord.org, passing 1,000,000 as of January 2013. Cord blood is used when the patient cannot find a matching bone marrow donor; this "extension" of the donor pool has driven the expansion of public banks. The umbilical cord in some mammals, including cows and sheep, contains two distinct umbilical veins. There is only one umbilical vein in the human umbilical cord. In some animals, the mother will gnaw through the cord, thus separating the placenta
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