For the first time, a patient's bladder has been mostly replaced with tissue grown in a laboratory oven from their own cells.
Sixteen-year-old Kaitlyne McNamara from Connecticut is at the centre of the breakthrough. Previously, scientists have only managed to grow simpler tissues like skin, bone and cartilage before transplanting them into humans.
Kaitlyne said: "I feel like I do have a body part that was grown, but it's my own body part." Mother Tracy McNamara said: "It's mind blowing. It's science fiction at its best."
Ok that's it! I want a second bladder so I don't have to get out of bed during the night, when I'm at the cinema half way through a film or on a long car journey! Just think of the possibilities!