. Umbilical cord blood. Technician placing metal boxes of umbilical cord blood into a cryostorage tank. The boxes contain blood that has been harvested from a placenta and an umbilical cord, after the birth of the baby that they supported. Liquid nitrogen is used to freeze the blood, which is quarantined for six months to allow further tests on the donor. The blood stem cells in the blood, which develop into red and white blood cells and platelets, can then be used to treat diseases like leukaemia, a cancer of the white blood cells. Photographed at the Northern Cord Blood Bank, Newcastle, England, part of the National Blood Service. MODEL RELEASED