FIGURE 1. Regeneration of cryopreserved newborn intestine. A, A representative newborn intestine (hematoxylin and eosin [H&E], original magnification ×20). B, A newborn intestine following cryopreservation (for 30 days) was transplanted subcutaneously into a syngeneic Lewis rat. It was examined at 1 POD (H&E, original magnification ×20). C, A newborn intestine following subcutaneous transplantation at 14 POD (H&E, original magnification ×20). D, A cryopreserved newborn intestine (Lewis; RT1^l) was transplanted into the allogeneic Brown Norway rat (RT1ⁿ), followed by treatment with the immunosuppressant drug, FK506 (tacrolimus, 0.64 mg/kg per day, intramuscularly) for 14 days (H&E, original magnification ×40).