Transplant was the medical procedure of using organic material from one source and incorporating it into another organism. This was most commonly used with bodily tissue (major organs, skin tissue, etc.).
In 2375, according to Doctor Julian Bashir, it was very difficult to keep a supply of synthetic organs on hand in a battlefield situation, and that one would never know how many livers or hearts you'd need. He claimed that the Holy Grail of organ replacement would be to come up with a way to inject the patient with undifferentiated tissue that could become whatever organ is needed. He had hoped that he could "borrow a cup of goo" from Odo, so as to study the Changeling's morphogenic matrix, in effort to find the means required to synthesize organic tissue that can change form the way Changeling cells do. (DS9: "When It Rains...")
The following is a detailed listing of all transplantation procedures performed by Starfleet medical personnel.
- In 2152, Doctor Phlox transplanted a pituitary gland from a Calrissian chameleon into Porthos, Captain Jonathan Archer's pet beagle, after it contracted a pathogen from Kreetassan's home planet. The pathogen had summarily weakened Porthos' immune system, causing the dog's original pituitary gland to fail. (ENT: "A Night in Sickbay")
- On Stardate 48532.4 (2371), The Doctor transplanted one of Kes' lungs into Neelix after both of his lungs were taken by the Vidiians. The Doctor was ultimately helped in this transplant by the Vidiians responsible in return for their release from USS Voyager. (VOY: "Phage")
- In 2372, The Doctor transplanted part of Lieutenant jg B'Elanna Torres' parietal lobe into the Vidiian Dr. Pel so that Torres' Klingon DNA would help stabilize Pel's bio-neural implant. (VOY: "Lifesigns")
- In 2374, Ishka, wife of Grand Nagus Zek, suffered a possible heart attack or cardiac arrest and had to be given a new heart by Chief Medical Officer Dr. Julian Bashir. (DS9: "Profit and Lace")