A method of preserving functionality of an organ. The method includes removing a whole organ and associated vasculature, cryo-preserving the whole organ, allowing a period of time to elapse, thawing the whole organ including vasculature and introducing the whole organ into a recipient so that the organ is supplied with blood by vasculature belonging to the recipient. Further disclosed is a method of preserving fertility of a patient undergoing a treatment expected to cause sterility. The method include removing a whole gonadal organ from the patient, cryo-preserving the whole gonadal organ, conducting the treatment and waiting for an effect thereof to subside, thawing the whole gonadal organ and introducing the whole gonadal organ where it is supplied with blood by the vasculature system of the patient. Further disclosed is a method of assuring a supply of viable gametes for future use, the method includes removing a whole gonadal organ from a patient, cryo-preserving the whole gonadal organ, waiting until viable gametes are desired by the patient, thawing the organ and introducing the gonadal organ into the patient so that it is supplied with blood by a vasculature system belonging to the patient.