It should be noted that most MTF reassignment techniques require an intact penis, which is destroyed in the process. It would not be possible for an MTF to donate her penis and also obtain a satisfactory surgical reassignment.
KellyM, I could google myself to death while probably more easily getting an accurate answer from you. Does your response above mean that an MTF sex change surgery involves basically turning the penis outside-in, and erectile tissue is removed and discarded in the process?
Ringo, in the most common form of male-to-female reassignment surgery, known as penile inversion, that is exactly what happens: the sheath is turned inside out and used to line the vagina, while the glans is used to form the clitoris. The corpus cavernosa and the testes are removed and discarded.
I am not aware of any form of reassignment surgery that preserves the penis intact or could be easily modified to do so. Any such procedure would be a nullification rather than a reassignment.