As the baby is born and the umbilical cord is separated, the blood can accumulate from the cord segment still connected to the placenta. Stem cells extracted from the blood in the remaining part of the placenta and the umbilical cord is known as "umbilical cord blood (UCB) cells." http://www.agriverdesa.it/index.php?option=com_k2&view=itemlist&task=user&id=628719