MODEL RELEASED. Storing umbilical cord blood stem cells. Technician placing blood stem cells collected from a donated human placenta and umbilical cord in to a cryostorage tank. The blood is frozen in liquid nitrogen to preserve it for future use. The stem cells are able to develop into any type of blood cell, and can be used to treat a number of diseases, including cancers, genetic diseases and blood disorders. The placenta lines the uterus (womb) during pregnancy, providing the foetus with oxygen and nutrients and removing waste products. The umbilical cord attaches the placenta to the foetus.